Re: question about autoguiding in maxim dl


May 5, 2006

 


----------------------------

#24035 May 5, 2006

OK, I'll try again.

I use MaximDL with the SXV guider on an ST80 guide scope to guide a

G11 with a C9.25 SCT and an f/6.3 focal reducer. The guiding is nice

and smooth in parts of the sky around Ursa Major but when I go out to

Coma Berenice the RA becomes a lot more unstable. Why does this

happen? What can I do to correct this? For example I did M109 with

good results and M85 with poor results, i.e., oval stars.



Jim Smith



----------------------------

#24039 May 5, 2006

By the way, I consider this a theoretical question instead of a

technical one. That is to say, I had the balance set correctly so

that wasn't the problem. There is something going on here that I

can't get a grip on and I hope someone can help me.

Jim



--- In MaxImDL@yahoogroups.com, "jameslexman" jksmit0@...> wrote:

>

> OK, I'll try again.

> I use MaximDL with the SXV guider on an ST80 guide scope to guide

a

> G11 with a C9.25 SCT and an f/6.3 focal reducer. The guiding is

nice

> and smooth in parts of the sky around Ursa Major but when I go out

to

> Coma Berenice the RA becomes a lot more unstable. Why does this

> happen? What can I do to correct this? For example I did M109

with

> good results and M85 with poor results, i.e., oval stars.

>

> Jim Smith

>



----------------------------

#24041 May 5, 2006

Hi Jim-



Tracking in RA gets better as you get closer to the poles. That's because

whatever sort of tracking error you have translates to fewer pixels near the

poles. 5 arcsec of error at declination +20. covers twice as many pixels as

it does at +60.. That may be part of what you are seeing. You could also

have a calibration issue. I calibrated once near the equator, and let Maxim

adjust for the declination. If you have bad calibration values, you may get

better corrections at some declinations than others.



Using an external guidescope means you have to be careful about differential

movement. It's possible that your SCT mirror shifts more when the scope is

pointing at certain parts of the sky (although not necessarily along the RA

axis).



Have you collected and analyzed a guider log?



Chris



*****************************************

Chris L Peterson

Cloudbait Observatory

www.cloudbait.com



----- Original Message -----

From: "jameslexman" jksmit0@...>

To: MaxImDL@yahoogroups.com>

Sent: Friday, May 05, 2006 7:03 PM

Subject: [MaxImDL] Question about autoguiding





OK, I'll try again.

I use MaximDL with the SXV guider on an ST80 guide scope to guide a

G11 with a C9.25 SCT and an f/6.3 focal reducer. The guiding is nice

and smooth in parts of the sky around Ursa Major but when I go out to

Coma Berenice the RA becomes a lot more unstable. Why does this

happen? What can I do to correct this? For example I did M109 with

good results and M85 with poor results, i.e., oval stars.



Jim Smith



----------------------------

#24046 May 6, 2006

Chris,

I suspected that the reason was because of what you say. I always

calibrate when I go to a new location. I have never used the

declination correction because I recalibrate each time. The way I

read the instructions, the declination correction was to be used so

that you would not have to recalibrate each time.



Another thing is this: I have never PE corrected the mount. It

doesn't seem to be necessary when I am guiding at about +60

degrees. The tracking graph is almost a straight line on both

axes. Get it out to +20 deg and the RA goes wild while the DEC is

still a straight line. I will analyze the tracking data to see what

it tells me.

Jim---

In MaxImDL@yahoogroups.com, "Chris Peterson" clp@...> wrote: >

> Hi Jim-

>

> Tracking in RA gets better as you get closer to the poles. That's

because > whatever sort of tracking error you have translates to fewer

pixels near the > poles. 5 arcsec of error at declination +20. covers twice as many

pixels as > it does at +60.. That may be part of what you are seeing. You

could also > have a calibration issue. I calibrated once near the equator, and

let Maxim > adjust for the declination. If you have bad calibration values,

you may get > better corrections at some declinations than others.

>

> Using an external guidescope means you have to be careful about

differential > movement. It's possible that your SCT mirror shifts more when the

scope is > pointing at certain parts of the sky (although not necessarily

along the RA > axis).

>

> Have you collected and analyzed a guider log?

>

> Chris

>

> *****************************************

> Chris L Peterson

> Cloudbait Observatory

> www.cloudbait.com

>

>

> ----- Original Message -----

> From: "jameslexman" jksmit0@...>

> To: MaxImDL@yahoogroups.com>

> Sent: Friday, May 05, 2006 7:03 PM

> Subject: [MaxImDL] Question about autoguiding

>

>

> OK, I'll try again.

> I use MaximDL with the SXV guider on an ST80 guide scope to guide a

> G11 with a C9.25 SCT and an f/6.3 focal reducer. The guiding is

nice > and smooth in parts of the sky around Ursa Major but when I go out

to > Coma Berenice the RA becomes a lot more unstable. Why does this

> happen? What can I do to correct this? For example I did M109

with > good results and M85 with poor results, i.e., oval stars.

>

> Jim Smith

>







----------------------------

#24049 May 6, 2006

If you recalibrate, should the declination be left alone at the

current value for where the scope is pointing?



Thanks,

-Dave

--- In MaxImDL@yahoogroups.com, "Chris Peterson" clp@...> wrote:

>

> Hi Jim-

>

> Tracking in RA gets better as you get closer to the poles. That's

because

> whatever sort of tracking error you have translates to fewer pixels

near the

> poles. 5 arcsec of error at declination +20. covers twice as many

pixels as

> it does at +60.. That may be part of what you are seeing. You could

also

> have a calibration issue. I calibrated once near the equator, and

let Maxim

> adjust for the declination. If you have bad calibration values, you

may get

> better corrections at some declinations than others.

>

> Using an external guidescope means you have to be careful about

differential

> movement. It's possible that your SCT mirror shifts more when the

scope is

> pointing at certain parts of the sky (although not necessarily along

the RA

> axis).

>

> Have you collected and analyzed a guider log?

>

> Chris

>

> *****************************************

> Chris L Peterson

> Cloudbait Observatory

> www.cloudbait.com

>

>

> ----- Original Message -----

> From: "jameslexman" jksmit0@...>

> To: MaxImDL@yahoogroups.com>

> Sent: Friday, May 05, 2006 7:03 PM

> Subject: [MaxImDL] Question about autoguiding

>

>

> OK, I'll try again.

> I use MaximDL with the SXV guider on an ST80 guide scope to guide a

> G11 with a C9.25 SCT and an f/6.3 focal reducer. The guiding is nice

> and smooth in parts of the sky around Ursa Major but when I go out to

> Coma Berenice the RA becomes a lot more unstable. Why does this

> happen? What can I do to correct this? For example I did M109 with

> good results and M85 with poor results, i.e., oval stars.

>

> Jim Smith

>



----------------------------

#24052 May 6, 2006

I'm not certain- I never recalibrate. My intuition suggests you should just

leave the setting for "Use telescope position" disabled if you recalibrate

in the area of your imaging target.



Chris



*****************************************

Chris L Peterson

Cloudbait Observatory

www.cloudbait.com



----- Original Message -----

From: "Dave Weaver" tak@...>

To: MaxImDL@yahoogroups.com>

Sent: Saturday, May 06, 2006 5:07 PM

Subject: [MaxImDL] Re: Question about autoguiding





If you recalibrate, should the declination be left alone at the

current value for where the scope is pointing?



Thanks,

-Dave



----------------------------

#24053 May 6, 2006

Dave



I would suggest you set the delination to 0 when you recalibrate near

the object your going to image.



I have found that to provide a better result in guiding for me.



Bob

--- In MaxImDL@yahoogroups.com, "Dave Weaver" tak@...> wrote:

>

> If you recalibrate, should the declination be left alone at the

> current value for where the scope is pointing?

>

> Thanks,

> -Dave

>

> --- In MaxImDL@yahoogroups.com, "Chris Peterson" clp@> wrote:

> >

> > Hi Jim-

> >

> > Tracking in RA gets better as you get closer to the poles. That's

> because

> > whatever sort of tracking error you have translates to fewer

pixels

> near the

> > poles. 5 arcsec of error at declination +20. covers twice as many

> pixels as

> > it does at +60.. That may be part of what you are seeing. You

could

> also

> > have a calibration issue. I calibrated once near the equator, and

> let Maxim

> > adjust for the declination. If you have bad calibration values,

you

> may get

> > better corrections at some declinations than others.

> >

> > Using an external guidescope means you have to be careful about

> differential

> > movement. It's possible that your SCT mirror shifts more when the

> scope is

> > pointing at certain parts of the sky (although not necessarily

along

> the RA

> > axis).

> >

> > Have you collected and analyzed a guider log?

> >

> > Chris

> >

> > *****************************************

> > Chris L Peterson

> > Cloudbait Observatory

> > www.cloudbait.com

> >

> >

> > ----- Original Message -----

> > From: "jameslexman" jksmit0@>

> > To: MaxImDL@yahoogroups.com>

> > Sent: Friday, May 05, 2006 7:03 PM

> > Subject: [MaxImDL] Question about autoguiding

> >

> >

> > OK, I'll try again.

> > I use MaximDL with the SXV guider on an ST80 guide scope to guide

a

> > G11 with a C9.25 SCT and an f/6.3 focal reducer. The guiding is

nice

> > and smooth in parts of the sky around Ursa Major but when I go

out to

> > Coma Berenice the RA becomes a lot more unstable. Why does this

> > happen? What can I do to correct this? For example I did M109

with

> > good results and M85 with poor results, i.e., oval stars.

> >

> > Jim Smith

> >

>







----------------------------

#24061 May 7, 2006

Dave Weaver wrote: >

> If you recalibrate, should the declination be left alone at the

> current value for where the scope is pointing?



If you always recalibrate, leave the Declination field set to zero (you'll have

to turn off Use Scope Dec if you have a telescope connected).



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



---------------



----------------------------

#24062 May 7, 2006

Doug,

That is a little pearl of wisdom that I'm sure will help me. I have

gone through the tutorials and McMillans paper and didn't see that.

Thanks,

Jim smith



--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@...>

wrote: >

> Dave Weaver wrote:

> >

> > If you recalibrate, should the declination be left alone at the

> > current value for where the scope is pointing?

>

> If you always recalibrate, leave the Declination field set to zero

(you'll have > to turn off Use Scope Dec if you have a telescope connected).

>

> Doug

>

---------------

>

> Doug George

> dgeorge@...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

---------------

>



----------------------------

#24064 May 7, 2006

Another thing is this: I have never PE corrected the mount. It

> doesn't seem to be necessary when I am guiding at about +60

> degrees. The tracking graph is almost a straight line on both

> axes. Get it out to +20 deg and the RA goes wild while the DEC is

> still a straight line.



At Dec +60, the RA drive isn't moving nearly as much as it does at

+20. (At Dec +90, you get no RA movement, and at Dec 0, you get

maximum movement.)



Since RA is changing little at +60, your autoguider can keep up with

the worm's PE. But at +20, the movement is greater, so the it has a

harder time. I suspect it will be even wilder at 0 degrees.



When autoguiding, the Dec axis changes only because of drift due to a

polar misalignment. In fact, if you were perfectly polar aligned,

there would be no need to even activate autoguiding on the Dec axis.

So it's no surprise that you're seeing a straight line there.



Hope this helps.



Mike

astronomy.mdodd.com



----------------------------

#24065 May 7, 2006

The drive is moving at the sidereal rate, like a clock, whether it

is at 0 deg or 90 deg. But when you point the scope toward

something at 0 deg the movement is more evident, and one degree

movement covers more distance than it does at the pole. It still

goes 360 degrees, or 24 hours, per day.

Jim Smith

--- In MaxImDL@yahoogroups.com, "Mike Dodd" mike@...> wrote:

>

> > Another thing is this: I have never PE corrected the mount.

It

> > doesn't seem to be necessary when I am guiding at about +60

> > degrees. The tracking graph is almost a straight line on both

> > axes. Get it out to +20 deg and the RA goes wild while the DEC

is

> > still a straight line.

>

> At Dec +60, the RA drive isn't moving nearly as much as it does at

> +20. (At Dec +90, you get no RA movement, and at Dec 0, you get

> maximum movement.)

>

> Since RA is changing little at +60, your autoguider can keep up

with

> the worm's PE. But at +20, the movement is greater, so the it has a

> harder time. I suspect it will be even wilder at 0 degrees.

>

> When autoguiding, the Dec axis changes only because of drift due

to a

> polar misalignment. In fact, if you were perfectly polar aligned,

> there would be no need to even activate autoguiding on the Dec

axis.

> So it's no surprise that you're seeing a straight line there.

>

> Hope this helps.

>

> Mike

> astronomy.mdodd.com

>



----------------------------

#24078 May 8, 2006

Rats! I was sure my problems were solved.

Jim



--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@...>

wrote: >

> jameslexman wrote:

> >

> > By the way, what do you mean by "if you have a telescope

> > connected"? don't you always have a telescope connected when you

> > are autoguiding? Or are you refering to serial connection?

> > Jim Smith

>

> I was referring to the serial connection.

>

> Doug

>

---------------

>

> Doug George

> dgeorge@...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

---------------

>







----------------------------

#24079 May 8, 2006

Doug:

Can I insert a question here about this ?

So if I am using my ST237a and have that connected to the laptop via

parallel, have it connected to the AG port on the mount using an RJ11 cable

then I would not turn of dec corrections ? But if I had a cable going from

the laptop serial to the mount, and used that to control the mount during

guiding I would turn off dec corrections ?

Also which type of control is better, have serial to mount to control

guiding or use the RJ11 from the ST237a to control guiding ?

Thanks



Sam



-----Original Message-----

From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com] On Behalf Of

jameslexman

Sent: Monday, May 08, 2006 3:43 PM

To: MaxImDL@yahoogroups.com

Subject: [MaxImDL] Re: Question about autoguiding



Rats! I was sure my problems were solved.

Jim



--- In MaxImDL@yahoogroups.com, "Douglas B. George" dgeorge@...>

wrote: >

> jameslexman wrote:

> >

> > By the way, what do you mean by "if you have a telescope

> > connected"? don't you always have a telescope connected when you

> > are autoguiding? Or are you refering to serial connection?

> > Jim Smith

>

> I was referring to the serial connection.

>

> Doug

>

---------------

>

> Doug George

> dgeorge@...

>

> Diffraction Limited

> Makers of Cyanogen Imaging Products

> www.cyanogen.com

>

> 25 Conover Street

> Ottawa, Ontario,

> Canada, K2G 4C3

>

> Phone: (613) 225-2732

> Fax: (613) 225-9688

>

---------------

>



















Yahoo! Groups Links



----------------------------

#24080 May 8, 2006

Sam Barziza wrote: >

> Doug:

> .Can I insert a question here about this ?

> So if I am using my ST237a and have that connected to the laptop via

> parallel, have it connected to the AG port on the mount using an RJ11 cable

> then I would not turn of dec corrections ? But if I had a cable going from

> the laptop serial to the mount, and used that to control the mount during

> guiding I would turn off dec corrections ?



Whoa, the terminology is getting confusing here.



The Declination COMPENSATION option is automatically turned on when you connect

to a telescope via the Telescope Control window. Declination compensation

allows you to move the telescope without recalibrating the autoguider. When a

telescope is connected, and the Use Scope Dec option is on (default), then the

declination field is automatically adjusted to match the current telescope position.



If you don't want to use declination compensation, then you should always set

Declination to zero. If you have a connection in the Telescope Control window,

then you need to turn OFF the Use Scope Dec option in order to be able to set

the Declination to zero.



All this has nothing to do with Declination CORRECTIONS, which I would interpret

as the actual commands that are going to the telescope during autoguiding.

> Also which type of control is better, have serial to mount to control

> guiding or use the RJ11 from the ST237a to control guiding ?

> Thanks



Either will work just fine. We have all those options because not everyone has

a camera with autoguider outputs.



Doug



---------------



Doug George

dgeorge@...



Diffraction Limited

Makers of Cyanogen Imaging Products

www.cyanogen.com



25 Conover Street

Ottawa, Ontario,

Canada, K2G 4C3



Phone: (613) 225-2732

Fax: (613) 225-9688



---------------



----------------------------

#24110 May 11, 2006

That is a little pearl of wisdom that I'm sure will help me. I have

> gone through the tutorials and McMillans paper and didn't see that.



That's because, like Peterson, McMillan "never" recalibrates, even though

he has a rotator and a german mount! If you do it right, it's not necessary

to recal over and over. If you recal at some dec other than 0 with the dec

set to 0, the cal will be valid only for points near that declination, and

you'll be forced to recal again and again and again..... :-)))



Imagine running completely automated for weeks or more all over the sky

without needing to recalibrate the guider. Thanks to MaxIm's most excellent

design, this is possible, even with a motor rotator!!!



-- Bob



----------------------------

#24111 May 11, 2006

I'll take this a step further...



I recalibrated my guider last August when I bought the rotator.

I've since added a 6.3 FR into the imaging train. All I did then

was manually adjust the x,y speeds to account for the FR (meaning I

reduced the values by multiplying by 0.63). I still haven't used

MaxIm to recalibrate. No need to. I've imaged probably 30 or more

targets since then (5 - 10 hours/target), each at a different camera

orientation and all over the sky. ACP automatically puts the

correct value into MaxIm's camera angle field so guiding works

perfectly; every target, every time. I never have to change my

min/max/aggressiveness settings from target to target or night to

night. (In fact, since I use ACP and do virtually all my imaging

unattended, it's not practical to make changes anyway. The only

thing that does change is the guide exposure length, which is

dynamically managed by ACP to insure sufficient/optimum guide star

SNR regardless of star brightness and/or filter.) I can honestly

say I have not lost one image due to a guiding problem.



If you've read my paper, you'll know I'm a big proponent of not

being too aggressive with your guiding. Primarily I recommend this

strategy to make sure you don't chase the seeing. A side benefit of

this approach is that the accuracy of the actual calibration isn't

all that critical since you only send a portion of the detected

correction to the mount anyway. "Perfect" calibration isn't

necessary if your aggressiveness is somewhere around 5. Indeed,

striving to have perfect calibration and guiding more aggressively

almost always ends up chasing the seeing such that results are

inferior (meaning bloated stars).



The "fly in this ointment" is when the mount has mechanical problems

such that it requires aggressive guiding to keep up with the

mechanical errors. In this case, you not only "chase the mechanical

errors" but also end up chasing the seeing as well because for each

guide cycle, you never know whether you are correcting for a

mechanical error or a seeing-induced error. The result, at best, is

bloated stars.



That's why it's so important to do everything you can to reduce the

mechanical errors first (meaning decent polar alignment and PEM

training) as the first step in successful autoguiding.



With regard to DEC Compensation, there is a large section in my

paper discussing it, what it does, and the potential issues that may

arise when using it (and/or recalibrating for each target). My

advice is to be aware of the issues and try it both ways. It will

be obvious whether using it improves or hurts your guiding results

(meaning oscillations in RA).



You can find my paper at:



acp4.dc3.com/McMillanAutoguiding11-2005.pdf



FWIW.



Jim McMillan





--- In MaxImDL@yahoogroups.com, Bob Denny rdenny@...> wrote:

>

> > That is a little pearl of wisdom that I'm sure will help me. I

have

> > gone through the tutorials and McMillans paper and didn't see

that.

>

> That's because, like Peterson, McMillan "never" recalibrates, even

though

> he has a rotator and a german mount! If you do it right, it's not

necessary

> to recal over and over. If you recal at some dec other than 0 with

the dec

> set to 0, the cal will be valid only for points near that

declination, and

> you'll be forced to recal again and again and again..... :-)))

>

> Imagine running completely automated for weeks or more all over

the sky

> without needing to recalibrate the guider. Thanks to MaxIm's most

excellent

> design, this is possible, even with a motor rotator!!!

>

> -- Bob

>







----------------------------

#24126 May 12, 2006

The "pearl of wisdom" that I thought I had found was in fact a

misunderstanding of Doug's comments. He cleared it up in his next

message. He was, in fact, referring to serial commands from the

scope to operate the scope from the computer. Not the autoguiding

connections and commands.



By the way, what is ACP?

Jim Smith



--- In MaxImDL@yahoogroups.com, "mcmillanjr4221" valueware@...>

wrote: >

> I'll take this a step further...

>

> I recalibrated my guider last August when I bought the rotator.

> I've since added a 6.3 FR into the imaging train. All I did then

> was manually adjust the x,y speeds to account for the FR (meaning

I > reduced the values by multiplying by 0.63). I still haven't used

> MaxIm to recalibrate. No need to. I've imaged probably 30 or

more > targets since then (5 - 10 hours/target), each at a different

camera > orientation and all over the sky. ACP automatically puts the

> correct value into MaxIm's camera angle field so guiding works

> perfectly; every target, every time. I never have to change my

> min/max/aggressiveness settings from target to target or night to

> night. (In fact, since I use ACP and do virtually all my imaging

> unattended, it's not practical to make changes anyway. The only

> thing that does change is the guide exposure length, which is

> dynamically managed by ACP to insure sufficient/optimum guide star

> SNR regardless of star brightness and/or filter.) I can honestly

> say I have not lost one image due to a guiding problem.

>

> If you've read my paper, you'll know I'm a big proponent of not

> being too aggressive with your guiding. Primarily I recommend

this > strategy to make sure you don't chase the seeing. A side benefit

of > this approach is that the accuracy of the actual calibration isn't

> all that critical since you only send a portion of the detected

> correction to the mount anyway. "Perfect" calibration isn't

> necessary if your aggressiveness is somewhere around 5. Indeed,

> striving to have perfect calibration and guiding more aggressively

> almost always ends up chasing the seeing such that results are

> inferior (meaning bloated stars).

>

> The "fly in this ointment" is when the mount has mechanical

problems > such that it requires aggressive guiding to keep up with the

> mechanical errors. In this case, you not only "chase the

mechanical > errors" but also end up chasing the seeing as well because for

each > guide cycle, you never know whether you are correcting for a

> mechanical error or a seeing-induced error. The result, at best,

is > bloated stars.

>

> That's why it's so important to do everything you can to reduce

the > mechanical errors first (meaning decent polar alignment and PEM

> training) as the first step in successful autoguiding.

>

> With regard to DEC Compensation, there is a large section in my

> paper discussing it, what it does, and the potential issues that

may > arise when using it (and/or recalibrating for each target). My

> advice is to be aware of the issues and try it both ways. It will

> be obvious whether using it improves or hurts your guiding results

> (meaning oscillations in RA).

>

> You can find my paper at:

>

> acp4.dc3.com/McMillanAutoguiding11-2005.pdf

>

> FWIW.

>

> Jim McMillan

>

>

>

> --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> >

> > > That is a little pearl of wisdom that I'm sure will help me.

I > have

> > > gone through the tutorials and McMillans paper and didn't see

> that.

> >

> > That's because, like Peterson, McMillan "never" recalibrates,

even > though

> > he has a rotator and a german mount! If you do it right, it's

not > necessary

> > to recal over and over. If you recal at some dec other than 0

with > the dec

> > set to 0, the cal will be valid only for points near that

> declination, and

> > you'll be forced to recal again and again and again..... :-)))

> >

> > Imagine running completely automated for weeks or more all over

> the sky

> > without needing to recalibrate the guider. Thanks to MaxIm's

most > excellent

> > design, this is possible, even with a motor rotator!!!

> >

> > -- Bob

> >

>



----------------------------

#24128 May 12, 2006

ACP is automation software which allows you to operate fully

unattended - meaning all aspects of image acquisition (and a fair

amount of processing as well if you want) are automated. See

dc3.com/ for more info. Highly recommended for any type of

imaging (both pretty picture and science).



Jim

--- In MaxImDL@yahoogroups.com, "jameslexman" jksmit0@...> wrote:

>

> The "pearl of wisdom" that I thought I had found was in fact a

> misunderstanding of Doug's comments. He cleared it up in his next

> message. He was, in fact, referring to serial commands from the

> scope to operate the scope from the computer. Not the autoguiding

> connections and commands.

>

> By the way, what is ACP?

> Jim Smith

>

> --- In MaxImDL@yahoogroups.com, "mcmillanjr4221" valueware@>

> wrote:

> >

> > I'll take this a step further...

> >

> > I recalibrated my guider last August when I bought the rotator.

> > I've since added a 6.3 FR into the imaging train. All I did

then

> > was manually adjust the x,y speeds to account for the FR

(meaning

> I

> > reduced the values by multiplying by 0.63). I still haven't

used

> > MaxIm to recalibrate. No need to. I've imaged probably 30 or

> more

> > targets since then (5 - 10 hours/target), each at a different

> camera

> > orientation and all over the sky. ACP automatically puts the

> > correct value into MaxIm's camera angle field so guiding works

> > perfectly; every target, every time. I never have to change my

> > min/max/aggressiveness settings from target to target or night

to

> > night. (In fact, since I use ACP and do virtually all my

imaging

> > unattended, it's not practical to make changes anyway. The only

> > thing that does change is the guide exposure length, which is

> > dynamically managed by ACP to insure sufficient/optimum guide

star

> > SNR regardless of star brightness and/or filter.) I can

honestly

> > say I have not lost one image due to a guiding problem.

> >

> > If you've read my paper, you'll know I'm a big proponent of not

> > being too aggressive with your guiding. Primarily I recommend

> this

> > strategy to make sure you don't chase the seeing. A side

benefit

> of

> > this approach is that the accuracy of the actual calibration

isn't

> > all that critical since you only send a portion of the detected

> > correction to the mount anyway. "Perfect" calibration isn't

> > necessary if your aggressiveness is somewhere around 5. Indeed,

> > striving to have perfect calibration and guiding more

aggressively

> > almost always ends up chasing the seeing such that results are

> > inferior (meaning bloated stars).

> >

> > The "fly in this ointment" is when the mount has mechanical

> problems

> > such that it requires aggressive guiding to keep up with the

> > mechanical errors. In this case, you not only "chase the

> mechanical

> > errors" but also end up chasing the seeing as well because for

> each

> > guide cycle, you never know whether you are correcting for a

> > mechanical error or a seeing-induced error. The result, at

best,

> is

> > bloated stars.

> >

> > That's why it's so important to do everything you can to reduce

> the

> > mechanical errors first (meaning decent polar alignment and PEM

> > training) as the first step in successful autoguiding.

> >

> > With regard to DEC Compensation, there is a large section in my

> > paper discussing it, what it does, and the potential issues that

> may

> > arise when using it (and/or recalibrating for each target). My

> > advice is to be aware of the issues and try it both ways. It

will

> > be obvious whether using it improves or hurts your guiding

results

> > (meaning oscillations in RA).

> >

> > You can find my paper at:

> >

> > acp4.dc3.com/McMillanAutoguiding11-2005.pdf

> >

> > FWIW.

> >

> > Jim McMillan

> >

> >

> >

> > --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> > >

> > > > That is a little pearl of wisdom that I'm sure will help

me.

> I

> > have

> > > > gone through the tutorials and McMillans paper and didn't

see

> > that.

> > >

> > > That's because, like Peterson, McMillan "never" recalibrates,

> even

> > though

> > > he has a rotator and a german mount! If you do it right, it's

> not

> > necessary

> > > to recal over and over. If you recal at some dec other than 0

> with

> > the dec

> > > set to 0, the cal will be valid only for points near that

> > declination, and

> > > you'll be forced to recal again and again and again..... :-)))

> > >

> > > Imagine running completely automated for weeks or more all

over

> > the sky

> > > without needing to recalibrate the guider. Thanks to MaxIm's

> most

> > excellent

> > > design, this is possible, even with a motor rotator!!!

> > >

> > > -- Bob

> > >

> >

>







----------------------------

#24132 May 12, 2006

Jim,



This is a wonderful paper! I had read it last year but didn't put too much

credence behind it because I was using an LX200GPS at the time and your

recommendations didn't seem to apply. That mount needed aggressive guider

correction at the expense of bloated stars. That is why I only used it for

imaging at sub 400mm FL's.



I recently up at used Tak EM200 and have been having inconsistent guiding

results over the last few weeks. After re-reading your paper, I decided to

partially dissemble the mount and check the mechanics. I found that the RA

worm had more friction and stiffness around about 1/2 of it's turn than the

other half or so. This supports some funky numbers I've seen while doing

hours of PE analysis of tracking logs and guider logs. I have been getting

perfectly OVAL stars oriented along the RA axis with longer 10min exposures.

5 min exposure were much better with only a few ruined exposures from bad

guiding. I've adjusted the worm block so now it feels consistently smooth

and buttery without any noticeable backlash during an entire 360 degree

rotation of the worm. This may have fixed that problem.



Hopefully tonight, the clouds will clear up enough to let me test your

recommendations with Maxim. I feel I'm at least armed with a good

understanding of the variables - especially the overcorrection and guide

star S/N regarding centroid calculations. I've noticed that I was getting

much better results with very bright stars for guiding than dim ones and I

suspected it was due to poor dynamic range.



I think the S/N ratio is even more important with certain cameras. I'm using

a DSI pro as a guider and I tell you, the stars look very ugly in it's raw

mode with non square pixels and the interlacing clearly visible between

rows. With it's lack of temperature regulation and sensors, it's very

difficult to get accurate dark subtraction to clean up the stray warm pixels

thereby confusing centroid calculations even more. Also, it takes a min of 3

secs to download a DSI frame using hi-speed USB and I believe there is

latency of 1 frame. Meaning, that the downloaded frame is probably at least

5 secs old or longer. I have no way to confirm this except when I use focus

mode and notice a change in focus requires me to wait an extra frame before

I see the results of my adjutment. Guider logs show that it is a min of 3

secs between each exposure, no matter how short the exposure time and I

believe those to be 1 frame older than the time stamp. I don't believe there

is a solution to this since the DSI does not support hardware subframes or

binning so the entire frame must be downloaded each time.



I'm relying on the smoothness of tracking on this mount with very subtle and

gentle guide correction over longer guide integrations to give me good

results at the longer focal lengths I am trying to shoot (1300mm up to

1800mm).



Wish me luck!



cheers,

Stef.











-----Original Message-----

From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On Behalf

Of mcmillanjr4221

Sent: Thursday, May 11, 2006 6:29 PM

To: MaxImDL@yahoogroups.com

Subject: [MaxImDL] Re: Question about autoguiding





I'll take this a step further...



I recalibrated my guider last August when I bought the rotator.

I've since added a 6.3 FR into the imaging train. All I did then

was manually adjust the x,y speeds to account for the FR (meaning I

reduced the values by multiplying by 0.63). I still haven't used

MaxIm to recalibrate. No need to. I've imaged probably 30 or more

targets since then (5 - 10 hours/target), each at a different camera

orientation and all over the sky. ACP automatically puts the

correct value into MaxIm's camera angle field so guiding works

perfectly; every target, every time. I never have to change my

min/max/aggressiveness settings from target to target or night to

night. (In fact, since I use ACP and do virtually all my imaging

unattended, it's not practical to make changes anyway. The only

thing that does change is the guide exposure length, which is

dynamically managed by ACP to insure sufficient/optimum guide star

SNR regardless of star brightness and/or filter.) I can honestly

say I have not lost one image due to a guiding problem.



If you've read my paper, you'll know I'm a big proponent of not

being too aggressive with your guiding. Primarily I recommend this

strategy to make sure you don't chase the seeing. A side benefit of

this approach is that the accuracy of the actual calibration isn't

all that critical since you only send a portion of the detected

correction to the mount anyway. "Perfect" calibration isn't

necessary if your aggressiveness is somewhere around 5. Indeed,

striving to have perfect calibration and guiding more aggressively

almost always ends up chasing the seeing such that results are

inferior (meaning bloated stars).



The "fly in this ointment" is when the mount has mechanical problems

such that it requires aggressive guiding to keep up with the

mechanical errors. In this case, you not only "chase the mechanical

errors" but also end up chasing the seeing as well because for each

guide cycle, you never know whether you are correcting for a

mechanical error or a seeing-induced error. The result, at best, is

bloated stars.



That's why it's so important to do everything you can to reduce the

mechanical errors first (meaning decent polar alignment and PEM

training) as the first step in successful autoguiding.



With regard to DEC Compensation, there is a large section in my

paper discussing it, what it does, and the potential issues that may

arise when using it (and/or recalibrating for each target). My

advice is to be aware of the issues and try it both ways. It will

be obvious whether using it improves or hurts your guiding results

(meaning oscillations in RA).



You can find my paper at:



acp4.dc3.com/McMillanAutoguiding11-2005.pdf



FWIW.



Jim McMillan





--- In MaxImDL@yahoogroups.com, Bob Denny rdenny@...> wrote:

>

> > That is a little pearl of wisdom that I'm sure will help me. I

have

> > gone through the tutorials and McMillans paper and didn't see

that.

>

> That's because, like Peterson, McMillan "never" recalibrates, even

though

> he has a rotator and a german mount! If you do it right, it's not

necessary

> to recal over and over. If you recal at some dec other than 0 with

the dec

> set to 0, the cal will be valid only for points near that

declination, and

> you'll be forced to recal again and again and again..... :-)))

>

> Imagine running completely automated for weeks or more all over

the sky

> without needing to recalibrate the guider. Thanks to MaxIm's most

excellent

> design, this is possible, even with a motor rotator!!!

>

> -- Bob

>

















Yahoo! Groups Links







----------------------------

#24134 May 12, 2006

Hi Stef,



Glad you found some value in my paper. Good luck getting the new

mount working well.



I had to smile regarding your comment about my recommendations not

being particularly applicable to your LX200. I guess I'd take the

view that while it may not have helped your guiding all that much,

it explained what was going on. Indeed, you ended up taking my 1st

recommendation quite seriously - do everything you can to minimize

the need for making corrections. You took it to the max - e.g.

replace the mount! In fact, that's just what I did as well!



Regards,



Jim



--- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@...>

wrote: >

> Jim,

>

> This is a wonderful paper! I had read it last year but didn't put

too much > credence behind it because I was using an LX200GPS at the time and

your > recommendations didn't seem to apply. That mount needed aggressive

guider > correction at the expense of bloated stars. That is why I only

used it for > imaging at sub 400mm FL's.

>

> I recently up at used Tak EM200 and have been having inconsistent

guiding > results over the last few weeks. After re-reading your paper, I

decided to > partially dissemble the mount and check the mechanics. I found

that the RA > worm had more friction and stiffness around about 1/2 of it's turn

than the > other half or so. This supports some funky numbers I've seen while

doing > hours of PE analysis of tracking logs and guider logs. I have been

getting > perfectly OVAL stars oriented along the RA axis with longer 10min

exposures. > 5 min exposure were much better with only a few ruined exposures

from bad > guiding. I've adjusted the worm block so now it feels consistently

smooth > and buttery without any noticeable backlash during an entire 360

degree > rotation of the worm. This may have fixed that problem.

>

> Hopefully tonight, the clouds will clear up enough to let me test

your > recommendations with Maxim. I feel I'm at least armed with a good

> understanding of the variables - especially the overcorrection and

guide > star S/N regarding centroid calculations. I've noticed that I was

getting > much better results with very bright stars for guiding than dim

ones and I > suspected it was due to poor dynamic range.

>

> I think the S/N ratio is even more important with certain cameras.

I'm using > a DSI pro as a guider and I tell you, the stars look very ugly in

it's raw > mode with non square pixels and the interlacing clearly visible

between > rows. With it's lack of temperature regulation and sensors, it's

very > difficult to get accurate dark subtraction to clean up the stray

warm pixels > thereby confusing centroid calculations even more. Also, it takes

a min of 3 > secs to download a DSI frame using hi-speed USB and I believe

there is > latency of 1 frame. Meaning, that the downloaded frame is probably

at least > 5 secs old or longer. I have no way to confirm this except when I

use focus > mode and notice a change in focus requires me to wait an extra

frame before > I see the results of my adjutment. Guider logs show that it is a

min of 3 > secs between each exposure, no matter how short the exposure time

and I > believe those to be 1 frame older than the time stamp. I don't

believe there > is a solution to this since the DSI does not support hardware

subframes or > binning so the entire frame must be downloaded each time.

>

> I'm relying on the smoothness of tracking on this mount with very

subtle and > gentle guide correction over longer guide integrations to give me

good > results at the longer focal lengths I am trying to shoot (1300mm

up to > 1800mm).

>

> Wish me luck!

>

> cheers,

> Stef.

>

>

>

>

>

> -----Original Message-----

> From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

Behalf > Of mcmillanjr4221

> Sent: Thursday, May 11, 2006 6:29 PM

> To: MaxImDL@yahoogroups.com

> Subject: [MaxImDL] Re: Question about autoguiding

>

>

> I'll take this a step further...

>

> I recalibrated my guider last August when I bought the rotator.

> I've since added a 6.3 FR into the imaging train. All I did then

> was manually adjust the x,y speeds to account for the FR (meaning I

> reduced the values by multiplying by 0.63). I still haven't used

> MaxIm to recalibrate. No need to. I've imaged probably 30 or more

> targets since then (5 - 10 hours/target), each at a different

camera > orientation and all over the sky. ACP automatically puts the

> correct value into MaxIm's camera angle field so guiding works

> perfectly; every target, every time. I never have to change my

> min/max/aggressiveness settings from target to target or night to

> night. (In fact, since I use ACP and do virtually all my imaging

> unattended, it's not practical to make changes anyway. The only

> thing that does change is the guide exposure length, which is

> dynamically managed by ACP to insure sufficient/optimum guide star

> SNR regardless of star brightness and/or filter.) I can honestly

> say I have not lost one image due to a guiding problem.

>

> If you've read my paper, you'll know I'm a big proponent of not

> being too aggressive with your guiding. Primarily I recommend this

> strategy to make sure you don't chase the seeing. A side benefit

of > this approach is that the accuracy of the actual calibration isn't

> all that critical since you only send a portion of the detected

> correction to the mount anyway. "Perfect" calibration isn't

> necessary if your aggressiveness is somewhere around 5. Indeed,

> striving to have perfect calibration and guiding more aggressively

> almost always ends up chasing the seeing such that results are

> inferior (meaning bloated stars).

>

> The "fly in this ointment" is when the mount has mechanical

problems > such that it requires aggressive guiding to keep up with the

> mechanical errors. In this case, you not only "chase the

mechanical > errors" but also end up chasing the seeing as well because for each

> guide cycle, you never know whether you are correcting for a

> mechanical error or a seeing-induced error. The result, at best,

is > bloated stars.

>

> That's why it's so important to do everything you can to reduce the

> mechanical errors first (meaning decent polar alignment and PEM

> training) as the first step in successful autoguiding.

>

> With regard to DEC Compensation, there is a large section in my

> paper discussing it, what it does, and the potential issues that

may > arise when using it (and/or recalibrating for each target). My

> advice is to be aware of the issues and try it both ways. It will

> be obvious whether using it improves or hurts your guiding results

> (meaning oscillations in RA).

>

> You can find my paper at:

>

> acp4.dc3.com/McMillanAutoguiding11-2005.pdf

>

> FWIW.

>

> Jim McMillan

>

>

>

> --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> >

> > > That is a little pearl of wisdom that I'm sure will help me. I

> have

> > > gone through the tutorials and McMillans paper and didn't see

> that.

> >

> > That's because, like Peterson, McMillan "never" recalibrates,

even > though

> > he has a rotator and a german mount! If you do it right, it's not

> necessary

> > to recal over and over. If you recal at some dec other than 0

with > the dec

> > set to 0, the cal will be valid only for points near that

> declination, and

> > you'll be forced to recal again and again and again..... :-)))

> >

> > Imagine running completely automated for weeks or more all over

> the sky

> > without needing to recalibrate the guider. Thanks to MaxIm's most

> excellent

> > design, this is possible, even with a motor rotator!!!

> >

> > -- Bob

> >

>

>

>

>

>

>

>

>

> Yahoo! Groups Links

>







----------------------------

#24139 May 13, 2006

Well Jim,



I'm happy to report near perfect guiding last night with Maxim :o).



I want claim to victory and do a celebration dance, but I might jinx it,

plus it's too early to tell. But, nice round stars with Maxim on a 5 min

guided exposure of m13. That's all the time I got before the clouds moved

in. Just had enough time to do a cal at 0 dec and then move to the target

and shoot.



I know this is nothing special, except that I did not need or try tweaking

with params which in itself is a big departure from my experiences of the

last few weeks. Min move was at 0.00 max move at 3 secs. My guide errors

were .045 X and .042 Y RMS values with never more than .15 pixels peak to

peak using a 300mm guide scope and my main scope at 1300mm. Seeing must have

been ok because it wasn't chasing and I was using 2 sec integrations. No

ovals!!! I think I should be able to get some tighter stars by using your

min/max move values. I'll just pretend this mount has the same

characteristics as an AP mount and use your numbers and see what happens

next opportunity. Bottom line is the PE is very smooth and I'm guessing has

improved by an arcsec or so but I need to run some extended logs to be sure.



Things are looking promising but I'm not counting the chickens yet. I want

to test at different DECS and on the other side of the meridian. I'm

definitely NOT going to use DEC compensation any more. I did the calib at 0

dec within 2 mins of the meridian using a guide speed of .5x with an

aggressiveness of 7.



Once again, thanks very much for authoring such a fine paper Jim! You can't

imagine the elation I felt watching the tracking graph sit on the zero line

for nearly 90% of the exposure time!



Cheers,

Stef



P.S. You mentioned a multiple star guider plug-in in your article. I haven't

been able to locate it on the net though and was wondering if it was still

available?







-----Original Message-----

From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On Behalf

Of mcmillanjr4221

Sent: Friday, May 12, 2006 3:27 PM

To: MaxImDL@yahoogroups.com

Subject: [MaxImDL] Re: Question about autoguiding





Hi Stef,



Glad you found some value in my paper. Good luck getting the new

mount working well.



I had to smile regarding your comment about my recommendations not

being particularly applicable to your LX200. I guess I'd take the

view that while it may not have helped your guiding all that much,

it explained what was going on. Indeed, you ended up taking my 1st

recommendation quite seriously - do everything you can to minimize

the need for making corrections. You took it to the max - e.g.

replace the mount! In fact, that's just what I did as well!



Regards,



Jim



--- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@...>

wrote: >

> Jim,

>

> This is a wonderful paper! I had read it last year but didn't put

too much > credence behind it because I was using an LX200GPS at the time and

your > recommendations didn't seem to apply. That mount needed aggressive

guider > correction at the expense of bloated stars. That is why I only

used it for > imaging at sub 400mm FL's.

>

> I recently up at used Tak EM200 and have been having inconsistent

guiding > results over the last few weeks. After re-reading your paper, I

decided to > partially dissemble the mount and check the mechanics. I found

that the RA > worm had more friction and stiffness around about 1/2 of it's turn

than the > other half or so. This supports some funky numbers I've seen while

doing > hours of PE analysis of tracking logs and guider logs. I have been

getting > perfectly OVAL stars oriented along the RA axis with longer 10min

exposures. > 5 min exposure were much better with only a few ruined exposures

from bad > guiding. I've adjusted the worm block so now it feels consistently

smooth > and buttery without any noticeable backlash during an entire 360

degree > rotation of the worm. This may have fixed that problem.

>

> Hopefully tonight, the clouds will clear up enough to let me test

your > recommendations with Maxim. I feel I'm at least armed with a good

> understanding of the variables - especially the overcorrection and

guide > star S/N regarding centroid calculations. I've noticed that I was

getting > much better results with very bright stars for guiding than dim

ones and I > suspected it was due to poor dynamic range.

>

> I think the S/N ratio is even more important with certain cameras.

I'm using > a DSI pro as a guider and I tell you, the stars look very ugly in

it's raw > mode with non square pixels and the interlacing clearly visible

between > rows. With it's lack of temperature regulation and sensors, it's

very > difficult to get accurate dark subtraction to clean up the stray

warm pixels > thereby confusing centroid calculations even more. Also, it takes

a min of 3 > secs to download a DSI frame using hi-speed USB and I believe

there is > latency of 1 frame. Meaning, that the downloaded frame is probably

at least > 5 secs old or longer. I have no way to confirm this except when I

use focus > mode and notice a change in focus requires me to wait an extra

frame before > I see the results of my adjutment. Guider logs show that it is a

min of 3 > secs between each exposure, no matter how short the exposure time

and I > believe those to be 1 frame older than the time stamp. I don't

believe there > is a solution to this since the DSI does not support hardware

subframes or > binning so the entire frame must be downloaded each time.

>

> I'm relying on the smoothness of tracking on this mount with very

subtle and > gentle guide correction over longer guide integrations to give me

good > results at the longer focal lengths I am trying to shoot (1300mm

up to > 1800mm).

>

> Wish me luck!

>

> cheers,

> Stef.

>

>

>

>

>

> -----Original Message-----

> From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

Behalf > Of mcmillanjr4221

> Sent: Thursday, May 11, 2006 6:29 PM

> To: MaxImDL@yahoogroups.com

> Subject: [MaxImDL] Re: Question about autoguiding

>

>

> I'll take this a step further...

>

> I recalibrated my guider last August when I bought the rotator.

> I've since added a 6.3 FR into the imaging train. All I did then

> was manually adjust the x,y speeds to account for the FR (meaning I

> reduced the values by multiplying by 0.63). I still haven't used

> MaxIm to recalibrate. No need to. I've imaged probably 30 or more

> targets since then (5 - 10 hours/target), each at a different

camera > orientation and all over the sky. ACP automatically puts the

> correct value into MaxIm's camera angle field so guiding works

> perfectly; every target, every time. I never have to change my

> min/max/aggressiveness settings from target to target or night to

> night. (In fact, since I use ACP and do virtually all my imaging

> unattended, it's not practical to make changes anyway. The only

> thing that does change is the guide exposure length, which is

> dynamically managed by ACP to insure sufficient/optimum guide star

> SNR regardless of star brightness and/or filter.) I can honestly

> say I have not lost one image due to a guiding problem.

>

> If you've read my paper, you'll know I'm a big proponent of not

> being too aggressive with your guiding. Primarily I recommend this

> strategy to make sure you don't chase the seeing. A side benefit

of > this approach is that the accuracy of the actual calibration isn't

> all that critical since you only send a portion of the detected

> correction to the mount anyway. "Perfect" calibration isn't

> necessary if your aggressiveness is somewhere around 5. Indeed,

> striving to have perfect calibration and guiding more aggressively

> almost always ends up chasing the seeing such that results are

> inferior (meaning bloated stars).

>

> The "fly in this ointment" is when the mount has mechanical

problems > such that it requires aggressive guiding to keep up with the

> mechanical errors. In this case, you not only "chase the

mechanical > errors" but also end up chasing the seeing as well because for each

> guide cycle, you never know whether you are correcting for a

> mechanical error or a seeing-induced error. The result, at best,

is > bloated stars.

>

> That's why it's so important to do everything you can to reduce the

> mechanical errors first (meaning decent polar alignment and PEM

> training) as the first step in successful autoguiding.

>

> With regard to DEC Compensation, there is a large section in my

> paper discussing it, what it does, and the potential issues that

may > arise when using it (and/or recalibrating for each target). My

> advice is to be aware of the issues and try it both ways. It will

> be obvious whether using it improves or hurts your guiding results

> (meaning oscillations in RA).

>

> You can find my paper at:

>

> acp4.dc3.com/McMillanAutoguiding11-2005.pdf

>

> FWIW.

>

> Jim McMillan

>

>

>

> --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> >

> > > That is a little pearl of wisdom that I'm sure will help me. I

> have

> > > gone through the tutorials and McMillans paper and didn't see

> that.

> >

> > That's because, like Peterson, McMillan "never" recalibrates,

even > though

> > he has a rotator and a german mount! If you do it right, it's not

> necessary

> > to recal over and over. If you recal at some dec other than 0

with > the dec

> > set to 0, the cal will be valid only for points near that

> declination, and

> > you'll be forced to recal again and again and again..... :-)))

> >

> > Imagine running completely automated for weeks or more all over

> the sky

> > without needing to recalibrate the guider. Thanks to MaxIm's most

> excellent

> > design, this is possible, even with a motor rotator!!!

> >

> > -- Bob

> >

>

>

>

>

>

>

>

>

> Yahoo! Groups Links

>



















Yahoo! Groups Links







----------------------------

#24142 May 13, 2006

Oh, pardon me. Toronto. What happens if you try guiding something

in Virgo or Coma Berenice like M85? I have been guiding very well

in the M13 latitudes(36 deg Dec.), but get up around 20 deg

declination and things go downhill.

Jim Smith



--- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@...>

wrote: >

> Well Jim,

>

> I'm happy to report near perfect guiding last night with Maxim :o).

>

> I want claim to victory and do a celebration dance, but I might

jinx it, > plus it's too early to tell. But, nice round stars with Maxim on a

5 min > guided exposure of m13. That's all the time I got before the

clouds moved > in. Just had enough time to do a cal at 0 dec and then move to the

target > and shoot.

>

> I know this is nothing special, except that I did not need or try

tweaking > with params which in itself is a big departure from my experiences

of the > last few weeks. Min move was at 0.00 max move at 3 secs. My guide

errors > were .045 X and .042 Y RMS values with never more than .15 pixels

peak to > peak using a 300mm guide scope and my main scope at 1300mm. Seeing

must have > been ok because it wasn't chasing and I was using 2 sec

integrations. No > ovals!!! I think I should be able to get some tighter stars by

using your > min/max move values. I'll just pretend this mount has the same

> characteristics as an AP mount and use your numbers and see what

happens > next opportunity. Bottom line is the PE is very smooth and I'm

guessing has > improved by an arcsec or so but I need to run some extended logs

to be sure. >

> Things are looking promising but I'm not counting the chickens

yet. I want > to test at different DECS and on the other side of the meridian.

I'm > definitely NOT going to use DEC compensation any more. I did the

calib at 0 > dec within 2 mins of the meridian using a guide speed of .5x with

an > aggressiveness of 7.

>

> Once again, thanks very much for authoring such a fine paper Jim!

You can't > imagine the elation I felt watching the tracking graph sit on the

zero line > for nearly 90% of the exposure time!

>

> Cheers,

> Stef

>

> P.S. You mentioned a multiple star guider plug-in in your article.

I haven't > been able to locate it on the net though and was wondering if it

was still > available?

>

>

>

> -----Original Message-----

> From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

Behalf > Of mcmillanjr4221

> Sent: Friday, May 12, 2006 3:27 PM

> To: MaxImDL@yahoogroups.com

> Subject: [MaxImDL] Re: Question about autoguiding

>

>

> Hi Stef,

>

> Glad you found some value in my paper. Good luck getting the new

> mount working well.

>

> I had to smile regarding your comment about my recommendations not

> being particularly applicable to your LX200. I guess I'd take the

> view that while it may not have helped your guiding all that much,

> it explained what was going on. Indeed, you ended up taking my 1st

> recommendation quite seriously - do everything you can to minimize

> the need for making corrections. You took it to the max - e.g.

> replace the mount! In fact, that's just what I did as well!

>

> Regards,

>

> Jim

>

> --- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@>

> wrote:

> >

> > Jim,

> >

> > This is a wonderful paper! I had read it last year but didn't put

> too much

> > credence behind it because I was using an LX200GPS at the time

and > your

> > recommendations didn't seem to apply. That mount needed

aggressive > guider

> > correction at the expense of bloated stars. That is why I only

> used it for

> > imaging at sub 400mm FL's.

> >

> > I recently up at used Tak EM200 and have been having

inconsistent > guiding

> > results over the last few weeks. After re-reading your paper, I

> decided to

> > partially dissemble the mount and check the mechanics. I found

> that the RA

> > worm had more friction and stiffness around about 1/2 of it's

turn > than the

> > other half or so. This supports some funky numbers I've seen

while > doing

> > hours of PE analysis of tracking logs and guider logs. I have

been > getting

> > perfectly OVAL stars oriented along the RA axis with longer 10min

> exposures.

> > 5 min exposure were much better with only a few ruined exposures

> from bad

> > guiding. I've adjusted the worm block so now it feels

consistently > smooth

> > and buttery without any noticeable backlash during an entire 360

> degree

> > rotation of the worm. This may have fixed that problem.

> >

> > Hopefully tonight, the clouds will clear up enough to let me test

> your

> > recommendations with Maxim. I feel I'm at least armed with a good

> > understanding of the variables - especially the overcorrection

and > guide

> > star S/N regarding centroid calculations. I've noticed that I was

> getting

> > much better results with very bright stars for guiding than dim

> ones and I

> > suspected it was due to poor dynamic range.

> >

> > I think the S/N ratio is even more important with certain

cameras. > I'm using

> > a DSI pro as a guider and I tell you, the stars look very ugly in

> it's raw

> > mode with non square pixels and the interlacing clearly visible

> between

> > rows. With it's lack of temperature regulation and sensors, it's

> very

> > difficult to get accurate dark subtraction to clean up the stray

> warm pixels

> > thereby confusing centroid calculations even more. Also, it takes

> a min of 3

> > secs to download a DSI frame using hi-speed USB and I believe

> there is

> > latency of 1 frame. Meaning, that the downloaded frame is

probably > at least

> > 5 secs old or longer. I have no way to confirm this except when I

> use focus

> > mode and notice a change in focus requires me to wait an extra

> frame before

> > I see the results of my adjutment. Guider logs show that it is a

> min of 3

> > secs between each exposure, no matter how short the exposure time

> and I

> > believe those to be 1 frame older than the time stamp. I don't

> believe there

> > is a solution to this since the DSI does not support hardware

> subframes or

> > binning so the entire frame must be downloaded each time.

> >

> > I'm relying on the smoothness of tracking on this mount with very

> subtle and

> > gentle guide correction over longer guide integrations to give me

> good

> > results at the longer focal lengths I am trying to shoot (1300mm

> up to

> > 1800mm).

> >

> > Wish me luck!

> >

> > cheers,

> > Stef.

> >

> >

> >

> >

> >

> > -----Original Message-----

> > From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

> Behalf

> > Of mcmillanjr4221

> > Sent: Thursday, May 11, 2006 6:29 PM

> > To: MaxImDL@yahoogroups.com

> > Subject: [MaxImDL] Re: Question about autoguiding

> >

> >

> > I'll take this a step further...

> >

> > I recalibrated my guider last August when I bought the rotator.

> > I've since added a 6.3 FR into the imaging train. All I did then

> > was manually adjust the x,y speeds to account for the FR

(meaning I > > reduced the values by multiplying by 0.63). I still haven't used

> > MaxIm to recalibrate. No need to. I've imaged probably 30 or

more > > targets since then (5 - 10 hours/target), each at a different

> camera

> > orientation and all over the sky. ACP automatically puts the

> > correct value into MaxIm's camera angle field so guiding works

> > perfectly; every target, every time. I never have to change my

> > min/max/aggressiveness settings from target to target or night to

> > night. (In fact, since I use ACP and do virtually all my imaging

> > unattended, it's not practical to make changes anyway. The only

> > thing that does change is the guide exposure length, which is

> > dynamically managed by ACP to insure sufficient/optimum guide

star > > SNR regardless of star brightness and/or filter.) I can honestly

> > say I have not lost one image due to a guiding problem.

> >

> > If you've read my paper, you'll know I'm a big proponent of not

> > being too aggressive with your guiding. Primarily I recommend

this > > strategy to make sure you don't chase the seeing. A side benefit

> of

> > this approach is that the accuracy of the actual calibration

isn't > > all that critical since you only send a portion of the detected

> > correction to the mount anyway. "Perfect" calibration isn't

> > necessary if your aggressiveness is somewhere around 5. Indeed,

> > striving to have perfect calibration and guiding more

aggressively > > almost always ends up chasing the seeing such that results are

> > inferior (meaning bloated stars).

> >

> > The "fly in this ointment" is when the mount has mechanical

> problems

> > such that it requires aggressive guiding to keep up with the

> > mechanical errors. In this case, you not only "chase the

> mechanical

> > errors" but also end up chasing the seeing as well because for

each > > guide cycle, you never know whether you are correcting for a

> > mechanical error or a seeing-induced error. The result, at best,

> is

> > bloated stars.

> >

> > That's why it's so important to do everything you can to reduce

the > > mechanical errors first (meaning decent polar alignment and PEM

> > training) as the first step in successful autoguiding.

> >

> > With regard to DEC Compensation, there is a large section in my

> > paper discussing it, what it does, and the potential issues that

> may

> > arise when using it (and/or recalibrating for each target). My

> > advice is to be aware of the issues and try it both ways. It

will > > be obvious whether using it improves or hurts your guiding

results > > (meaning oscillations in RA).

> >

> > You can find my paper at:

> >

> > acp4.dc3.com/McMillanAutoguiding11-2005.pdf

> >

> > FWIW.

> >

> > Jim McMillan

> >

> >

> >

> > --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> > >

> > > > That is a little pearl of wisdom that I'm sure will help

me. I > > have

> > > > gone through the tutorials and McMillans paper and didn't see

> > that.

> > >

> > > That's because, like Peterson, McMillan "never" recalibrates,

> even

> > though

> > > he has a rotator and a german mount! If you do it right, it's

not > > necessary

> > > to recal over and over. If you recal at some dec other than 0

> with

> > the dec

> > > set to 0, the cal will be valid only for points near that

> > declination, and

> > > you'll be forced to recal again and again and again..... :-)))

> > >

> > > Imagine running completely automated for weeks or more all over

> > the sky

> > > without needing to recalibrate the guider. Thanks to MaxIm's

most > > excellent

> > > design, this is possible, even with a motor rotator!!!

> > >

> > > -- Bob

> > >

> >

> >

> >

> >

> >

> >

> >

> >

> > Yahoo! Groups Links

> >

>

>

>

>

>

>

>

>

>

> Yahoo! Groups Links

>







----------------------------

#24143 May 13, 2006

Stef,

What is your location?

Jim smith

--- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@...>

wrote: >

> Well Jim,

>

> I'm happy to report near perfect guiding last night with Maxim :o).

>

> I want claim to victory and do a celebration dance, but I might

jinx it, > plus it's too early to tell. But, nice round stars with Maxim on a

5 min > guided exposure of m13. That's all the time I got before the

clouds moved > in. Just had enough time to do a cal at 0 dec and then move to the

target > and shoot.

>

> I know this is nothing special, except that I did not need or try

tweaking > with params which in itself is a big departure from my experiences

of the > last few weeks. Min move was at 0.00 max move at 3 secs. My guide

errors > were .045 X and .042 Y RMS values with never more than .15 pixels

peak to > peak using a 300mm guide scope and my main scope at 1300mm. Seeing

must have > been ok because it wasn't chasing and I was using 2 sec

integrations. No > ovals!!! I think I should be able to get some tighter stars by

using your > min/max move values. I'll just pretend this mount has the same

> characteristics as an AP mount and use your numbers and see what

happens > next opportunity. Bottom line is the PE is very smooth and I'm

guessing has > improved by an arcsec or so but I need to run some extended logs

to be sure. >

> Things are looking promising but I'm not counting the chickens

yet. I want > to test at different DECS and on the other side of the meridian.

I'm > definitely NOT going to use DEC compensation any more. I did the

calib at 0 > dec within 2 mins of the meridian using a guide speed of .5x with

an > aggressiveness of 7.

>

> Once again, thanks very much for authoring such a fine paper Jim!

You can't > imagine the elation I felt watching the tracking graph sit on the

zero line > for nearly 90% of the exposure time!

>

> Cheers,

> Stef

>

> P.S. You mentioned a multiple star guider plug-in in your article.

I haven't > been able to locate it on the net though and was wondering if it

was still > available?

>

>

>

> -----Original Message-----

> From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

Behalf > Of mcmillanjr4221

> Sent: Friday, May 12, 2006 3:27 PM

> To: MaxImDL@yahoogroups.com

> Subject: [MaxImDL] Re: Question about autoguiding

>

>

> Hi Stef,

>

> Glad you found some value in my paper. Good luck getting the new

> mount working well.

>

> I had to smile regarding your comment about my recommendations not

> being particularly applicable to your LX200. I guess I'd take the

> view that while it may not have helped your guiding all that much,

> it explained what was going on. Indeed, you ended up taking my 1st

> recommendation quite seriously - do everything you can to minimize

> the need for making corrections. You took it to the max - e.g.

> replace the mount! In fact, that's just what I did as well!

>

> Regards,

>

> Jim

>

> --- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@>

> wrote:

> >

> > Jim,

> >

> > This is a wonderful paper! I had read it last year but didn't put

> too much

> > credence behind it because I was using an LX200GPS at the time

and > your

> > recommendations didn't seem to apply. That mount needed

aggressive > guider

> > correction at the expense of bloated stars. That is why I only

> used it for

> > imaging at sub 400mm FL's.

> >

> > I recently up at used Tak EM200 and have been having

inconsistent > guiding

> > results over the last few weeks. After re-reading your paper, I

> decided to

> > partially dissemble the mount and check the mechanics. I found

> that the RA

> > worm had more friction and stiffness around about 1/2 of it's

turn > than the

> > other half or so. This supports some funky numbers I've seen

while > doing

> > hours of PE analysis of tracking logs and guider logs. I have

been > getting

> > perfectly OVAL stars oriented along the RA axis with longer 10min

> exposures.

> > 5 min exposure were much better with only a few ruined exposures

> from bad

> > guiding. I've adjusted the worm block so now it feels

consistently > smooth

> > and buttery without any noticeable backlash during an entire 360

> degree

> > rotation of the worm. This may have fixed that problem.

> >

> > Hopefully tonight, the clouds will clear up enough to let me test

> your

> > recommendations with Maxim. I feel I'm at least armed with a good

> > understanding of the variables - especially the overcorrection

and > guide

> > star S/N regarding centroid calculations. I've noticed that I was

> getting

> > much better results with very bright stars for guiding than dim

> ones and I

> > suspected it was due to poor dynamic range.

> >

> > I think the S/N ratio is even more important with certain

cameras. > I'm using

> > a DSI pro as a guider and I tell you, the stars look very ugly in

> it's raw

> > mode with non square pixels and the interlacing clearly visible

> between

> > rows. With it's lack of temperature regulation and sensors, it's

> very

> > difficult to get accurate dark subtraction to clean up the stray

> warm pixels

> > thereby confusing centroid calculations even more. Also, it takes

> a min of 3

> > secs to download a DSI frame using hi-speed USB and I believe

> there is

> > latency of 1 frame. Meaning, that the downloaded frame is

probably > at least

> > 5 secs old or longer. I have no way to confirm this except when I

> use focus

> > mode and notice a change in focus requires me to wait an extra

> frame before

> > I see the results of my adjutment. Guider logs show that it is a

> min of 3

> > secs between each exposure, no matter how short the exposure time

> and I

> > believe those to be 1 frame older than the time stamp. I don't

> believe there

> > is a solution to this since the DSI does not support hardware

> subframes or

> > binning so the entire frame must be downloaded each time.

> >

> > I'm relying on the smoothness of tracking on this mount with very

> subtle and

> > gentle guide correction over longer guide integrations to give me

> good

> > results at the longer focal lengths I am trying to shoot (1300mm

> up to

> > 1800mm).

> >

> > Wish me luck!

> >

> > cheers,

> > Stef.

> >

> >

> >

> >

> >

> > -----Original Message-----

> > From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

> Behalf

> > Of mcmillanjr4221

> > Sent: Thursday, May 11, 2006 6:29 PM

> > To: MaxImDL@yahoogroups.com

> > Subject: [MaxImDL] Re: Question about autoguiding

> >

> >

> > I'll take this a step further...

> >

> > I recalibrated my guider last August when I bought the rotator.

> > I've since added a 6.3 FR into the imaging train. All I did then

> > was manually adjust the x,y speeds to account for the FR

(meaning I > > reduced the values by multiplying by 0.63). I still haven't used

> > MaxIm to recalibrate. No need to. I've imaged probably 30 or

more > > targets since then (5 - 10 hours/target), each at a different

> camera

> > orientation and all over the sky. ACP automatically puts the

> > correct value into MaxIm's camera angle field so guiding works

> > perfectly; every target, every time. I never have to change my

> > min/max/aggressiveness settings from target to target or night to

> > night. (In fact, since I use ACP and do virtually all my imaging

> > unattended, it's not practical to make changes anyway. The only

> > thing that does change is the guide exposure length, which is

> > dynamically managed by ACP to insure sufficient/optimum guide

star > > SNR regardless of star brightness and/or filter.) I can honestly

> > say I have not lost one image due to a guiding problem.

> >

> > If you've read my paper, you'll know I'm a big proponent of not

> > being too aggressive with your guiding. Primarily I recommend

this > > strategy to make sure you don't chase the seeing. A side benefit

> of

> > this approach is that the accuracy of the actual calibration

isn't > > all that critical since you only send a portion of the detected

> > correction to the mount anyway. "Perfect" calibration isn't

> > necessary if your aggressiveness is somewhere around 5. Indeed,

> > striving to have perfect calibration and guiding more

aggressively > > almost always ends up chasing the seeing such that results are

> > inferior (meaning bloated stars).

> >

> > The "fly in this ointment" is when the mount has mechanical

> problems

> > such that it requires aggressive guiding to keep up with the

> > mechanical errors. In this case, you not only "chase the

> mechanical

> > errors" but also end up chasing the seeing as well because for

each > > guide cycle, you never know whether you are correcting for a

> > mechanical error or a seeing-induced error. The result, at best,

> is

> > bloated stars.

> >

> > That's why it's so important to do everything you can to reduce

the > > mechanical errors first (meaning decent polar alignment and PEM

> > training) as the first step in successful autoguiding.

> >

> > With regard to DEC Compensation, there is a large section in my

> > paper discussing it, what it does, and the potential issues that

> may

> > arise when using it (and/or recalibrating for each target). My

> > advice is to be aware of the issues and try it both ways. It

will > > be obvious whether using it improves or hurts your guiding

results > > (meaning oscillations in RA).

> >

> > You can find my paper at:

> >

> > acp4.dc3.com/McMillanAutoguiding11-2005.pdf

> >

> > FWIW.

> >

> > Jim McMillan

> >

> >

> >

> > --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> > >

> > > > That is a little pearl of wisdom that I'm sure will help

me. I > > have

> > > > gone through the tutorials and McMillans paper and didn't see

> > that.

> > >

> > > That's because, like Peterson, McMillan "never" recalibrates,

> even

> > though

> > > he has a rotator and a german mount! If you do it right, it's

not > > necessary

> > > to recal over and over. If you recal at some dec other than 0

> with

> > the dec

> > > set to 0, the cal will be valid only for points near that

> > declination, and

> > > you'll be forced to recal again and again and again..... :-)))

> > >

> > > Imagine running completely automated for weeks or more all over

> > the sky

> > > without needing to recalibrate the guider. Thanks to MaxIm's

most > > excellent

> > > design, this is possible, even with a motor rotator!!!

> > >

> > > -- Bob

> > >

> >

> >

> >

> >

> >

> >

> >

> >

> > Yahoo! Groups Links

> >

>

>

>

>

>

>

>

>

>

> Yahoo! Groups Links

>







----------------------------

#24148 May 13, 2006

Great!



Regarding the multi-star guiding plug-in, John Winfield wrote it.

It can be found here:



winfij.homeip.net/maximdl/index.html



Hope all continues well!



Jim



--- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@...>

wrote: >

> Well Jim,

>

> I'm happy to report near perfect guiding last night with Maxim :o).

>

> I want claim to victory and do a celebration dance, but I might

jinx it, > plus it's too early to tell. But, nice round stars with Maxim on a

5 min > guided exposure of m13. That's all the time I got before the

clouds moved > in. Just had enough time to do a cal at 0 dec and then move to the

target > and shoot.

>

> I know this is nothing special, except that I did not need or try

tweaking > with params which in itself is a big departure from my experiences

of the > last few weeks. Min move was at 0.00 max move at 3 secs. My guide

errors > were .045 X and .042 Y RMS values with never more than .15 pixels

peak to > peak using a 300mm guide scope and my main scope at 1300mm. Seeing

must have > been ok because it wasn't chasing and I was using 2 sec

integrations. No > ovals!!! I think I should be able to get some tighter stars by

using your > min/max move values. I'll just pretend this mount has the same

> characteristics as an AP mount and use your numbers and see what

happens > next opportunity. Bottom line is the PE is very smooth and I'm

guessing has > improved by an arcsec or so but I need to run some extended logs

to be sure. >

> Things are looking promising but I'm not counting the chickens

yet. I want > to test at different DECS and on the other side of the meridian.

I'm > definitely NOT going to use DEC compensation any more. I did the

calib at 0 > dec within 2 mins of the meridian using a guide speed of .5x with

an > aggressiveness of 7.

>

> Once again, thanks very much for authoring such a fine paper Jim!

You can't > imagine the elation I felt watching the tracking graph sit on the

zero line > for nearly 90% of the exposure time!

>

> Cheers,

> Stef

>

> P.S. You mentioned a multiple star guider plug-in in your article.

I haven't > been able to locate it on the net though and was wondering if it

was still > available?

>

>

>

> -----Original Message-----

> From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

Behalf > Of mcmillanjr4221

> Sent: Friday, May 12, 2006 3:27 PM

> To: MaxImDL@yahoogroups.com

> Subject: [MaxImDL] Re: Question about autoguiding

>

>

> Hi Stef,

>

> Glad you found some value in my paper. Good luck getting the new

> mount working well.

>

> I had to smile regarding your comment about my recommendations not

> being particularly applicable to your LX200. I guess I'd take the

> view that while it may not have helped your guiding all that much,

> it explained what was going on. Indeed, you ended up taking my 1st

> recommendation quite seriously - do everything you can to minimize

> the need for making corrections. You took it to the max - e.g.

> replace the mount! In fact, that's just what I did as well!

>

> Regards,

>

> Jim

>

> --- In MaxImDL@yahoogroups.com, "Stef Cancelli" scancelli@>

> wrote:

> >

> > Jim,

> >

> > This is a wonderful paper! I had read it last year but didn't put

> too much

> > credence behind it because I was using an LX200GPS at the time

and > your

> > recommendations didn't seem to apply. That mount needed

aggressive > guider

> > correction at the expense of bloated stars. That is why I only

> used it for

> > imaging at sub 400mm FL's.

> >

> > I recently up at used Tak EM200 and have been having

inconsistent > guiding

> > results over the last few weeks. After re-reading your paper, I

> decided to

> > partially dissemble the mount and check the mechanics. I found

> that the RA

> > worm had more friction and stiffness around about 1/2 of it's

turn > than the

> > other half or so. This supports some funky numbers I've seen

while > doing

> > hours of PE analysis of tracking logs and guider logs. I have

been > getting

> > perfectly OVAL stars oriented along the RA axis with longer 10min

> exposures.

> > 5 min exposure were much better with only a few ruined exposures

> from bad

> > guiding. I've adjusted the worm block so now it feels

consistently > smooth

> > and buttery without any noticeable backlash during an entire 360

> degree

> > rotation of the worm. This may have fixed that problem.

> >

> > Hopefully tonight, the clouds will clear up enough to let me test

> your

> > recommendations with Maxim. I feel I'm at least armed with a good

> > understanding of the variables - especially the overcorrection

and > guide

> > star S/N regarding centroid calculations. I've noticed that I was

> getting

> > much better results with very bright stars for guiding than dim

> ones and I

> > suspected it was due to poor dynamic range.

> >

> > I think the S/N ratio is even more important with certain

cameras. > I'm using

> > a DSI pro as a guider and I tell you, the stars look very ugly in

> it's raw

> > mode with non square pixels and the interlacing clearly visible

> between

> > rows. With it's lack of temperature regulation and sensors, it's

> very

> > difficult to get accurate dark subtraction to clean up the stray

> warm pixels

> > thereby confusing centroid calculations even more. Also, it takes

> a min of 3

> > secs to download a DSI frame using hi-speed USB and I believe

> there is

> > latency of 1 frame. Meaning, that the downloaded frame is

probably > at least

> > 5 secs old or longer. I have no way to confirm this except when I

> use focus

> > mode and notice a change in focus requires me to wait an extra

> frame before

> > I see the results of my adjutment. Guider logs show that it is a

> min of 3

> > secs between each exposure, no matter how short the exposure time

> and I

> > believe those to be 1 frame older than the time stamp. I don't

> believe there

> > is a solution to this since the DSI does not support hardware

> subframes or

> > binning so the entire frame must be downloaded each time.

> >

> > I'm relying on the smoothness of tracking on this mount with very

> subtle and

> > gentle guide correction over longer guide integrations to give me

> good

> > results at the longer focal lengths I am trying to shoot (1300mm

> up to

> > 1800mm).

> >

> > Wish me luck!

> >

> > cheers,

> > Stef.

> >

> >

> >

> >

> >

> > -----Original Message-----

> > From: MaxImDL@yahoogroups.com [mailto:MaxImDL@yahoogroups.com]On

> Behalf

> > Of mcmillanjr4221

> > Sent: Thursday, May 11, 2006 6:29 PM

> > To: MaxImDL@yahoogroups.com

> > Subject: [MaxImDL] Re: Question about autoguiding

> >

> >

> > I'll take this a step further...

> >

> > I recalibrated my guider last August when I bought the rotator.

> > I've since added a 6.3 FR into the imaging train. All I did then

> > was manually adjust the x,y speeds to account for the FR

(meaning I > > reduced the values by multiplying by 0.63). I still haven't used

> > MaxIm to recalibrate. No need to. I've imaged probably 30 or

more > > targets since then (5 - 10 hours/target), each at a different

> camera

> > orientation and all over the sky. ACP automatically puts the

> > correct value into MaxIm's camera angle field so guiding works

> > perfectly; every target, every time. I never have to change my

> > min/max/aggressiveness settings from target to target or night to

> > night. (In fact, since I use ACP and do virtually all my imaging

> > unattended, it's not practical to make changes anyway. The only

> > thing that does change is the guide exposure length, which is

> > dynamically managed by ACP to insure sufficient/optimum guide

star > > SNR regardless of star brightness and/or filter.) I can honestly

> > say I have not lost one image due to a guiding problem.

> >

> > If you've read my paper, you'll know I'm a big proponent of not

> > being too aggressive with your guiding. Primarily I recommend

this > > strategy to make sure you don't chase the seeing. A side benefit

> of

> > this approach is that the accuracy of the actual calibration

isn't > > all that critical since you only send a portion of the detected

> > correction to the mount anyway. "Perfect" calibration isn't

> > necessary if your aggressiveness is somewhere around 5. Indeed,

> > striving to have perfect calibration and guiding more

aggressively > > almost always ends up chasing the seeing such that results are

> > inferior (meaning bloated stars).

> >

> > The "fly in this ointment" is when the mount has mechanical

> problems

> > such that it requires aggressive guiding to keep up with the

> > mechanical errors. In this case, you not only "chase the

> mechanical

> > errors" but also end up chasing the seeing as well because for

each > > guide cycle, you never know whether you are correcting for a

> > mechanical error or a seeing-induced error. The result, at best,

> is

> > bloated stars.

> >

> > That's why it's so important to do everything you can to reduce

the > > mechanical errors first (meaning decent polar alignment and PEM

> > training) as the first step in successful autoguiding.

> >

> > With regard to DEC Compensation, there is a large section in my

> > paper discussing it, what it does, and the potential issues that

> may

> > arise when using it (and/or recalibrating for each target). My

> > advice is to be aware of the issues and try it both ways. It

will > > be obvious whether using it improves or hurts your guiding

results > > (meaning oscillations in RA).

> >

> > You can find my paper at:

> >

> > acp4.dc3.com/McMillanAutoguiding11-2005.pdf

> >

> > FWIW.

> >

> > Jim McMillan

> >

> >

> >

> > --- In MaxImDL@yahoogroups.com, Bob Denny rdenny@> wrote:

> > >

> > > > That is a little pearl of wisdom that I'm sure will help

me. I > > have

> > > > gone through the tutorials and McMillans paper and didn't see

> > that.

> > >

> > > That's because, like Peterson, McMillan "never" recalibrates,

> even

> > though

> > > he has a rotator and a german mount! If you do it right, it's

not > > necessary

> > > to recal over and over. If you recal at some dec other than 0

> with

> > the dec

> > > set to 0, the cal will be valid only for points near that

> > declination, and

> > > you'll be forced to recal again and again and again..... :-)))

> > >

> > > Imagine running completely automated for weeks or more all over

> > the sky

> > > without needing to recalibrate the guider. Thanks to MaxIm's

most > > excellent

> > > design, this is possible, even with a motor rotator!!!

> > >

> > > -- Bob

> > >

> >

> >

> >

> >

> >

> >

> >

> >

> > Yahoo! Groups Links

> >

>

>

>

>

>

>

>

>

>

> Yahoo! Groups Links

>







----------------------------

#36307 Apr 2, 2009

hello,



I have a little question about maxim dl

When maxim dl lost the guide star because there is smog for exemple i know that it make a alarm but i don't know if it stop guiding?

Is there an option to stop guiding when maxim lost the guid star?



Thank

Vincent



----------------------------

#36314 Apr 3, 2009

Hi Vincent,



I do not have an answer for that good question but I am also interested in knowing if MaximDL just stays put when the guide star is lost.



Neither PHD, K3CCD Tools or even GuideMaster stay put. All three programs start to wildly search for the lost guide star for about 5 to 10 seconds and in that time the image one is taking is spoiled.



Here you can see an example of what PHD made with an image at 3000mm focal length



rainerehlert.com/PHD/PHD-Problem-00.jpg



rainerehlert.com/PHD/PHD-Problem-01.jpg



That was a mag 5.8 star in teh center.



Thanks in advance for any comments ...



regards Rainer







>

> hello,

>

> I have a little question about maxim dl

> When maxim dl lost the guide star because there is smog for exemple i know that it make a alarm but i don't know if it stop guiding?

> Is there an option to stop guiding when maxim lost the guid star?

>

> Thank

> Vincent

>



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