Re: [ap-gto] 400GTO Guiding Question


Aug 28, 2003

 


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

#8436 Aug 28, 2003

Hi,

I recently acquired a used 400GTO and have tried guiding the mount with my

ST4 while piggy backing a camera for wide field shots.

This is my first GEM and I most likely have multiple issues to deal with

here.



I believe my polar alignment was reasonably good, although I didn't spend a

great deal of time refining it. I know the ST4 is in good working order,

I've had fairly good success guiding my LX200, at least as good as possible

with that setup. When I tried calibrating the ST4 I didn't get any movement

in the'x' axis using .5x or 1x rates set on the keypad. I tried changing the

rate to 64x and it did calibrate just fine, although it drove the star off

of the chip and back on again during the calibrate process. With the ST4 in

'find and focus' mode I tried moving the mount using the keypad set at .5x

or 1x and had to hold the keypad down for a fairly long time (5-7 se'conds)

to even get 2-3 units of change on the ST4 readout.



After getting it to calibrate at 64x I started guiding to see the results

and it seemed to start fine, but the movement in the 'x axis gradually

started climbing until it reached "e". The "y" axis had 0 to 2 in the

readout. If I just left the mount in "find and focus" there was very little

movement in either the x or y axis for up to 5 minutes or so.

At one point with the scope pointing straight overhead I had A0's to A1's

for almost 5 minutes. Then later I was pointing about 30 degrees above the

western horizon and the 'x' axis would climb gradually to 'e'.

I was guiding through a 4" f5.4 scope and had a 35mm camera on the scope.

Total weight approx 16lbs.

I haven't had the film developed yet to see if the polar alignment was off,

it's E200 slide film and I'm out town in Florida for the Mars opposition.

Currently the weather is not cooperating much either.



I think the scope was properly balanced, but this is uncertain, since I'm

going on little information.



Any help or suggestions would be appreciated.



Scott Hammonds



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

#8437 Aug 28, 2003

Scott,



I suspect you did not get a good calibration. You should experiment with

the C1 and C2 parameters. This parameter controls the time the ST-4 moves

each drive axis during calibration. Calibration is necessary for the ST-4

to learn the correction speed required, for your particular system to move a

star n number of pixels. You should calibrate each time you begin a

photograph as calibration is sensitive to the sky location. I recommend

that you experiment with how long a calibration time you can use without

moving the star off the CCD or beyond 30 units. Start calibrating with the

star close to the CCD center. I recommend using whatever time produces at

least a 10 count movement, because it seems to produce more accurate

guiding. This is just intuition on my part.



The AP mounts guide and calibrate just fine at 1x. Once you have a good

calibration with the star returning to the starting point + or - about 2

counts you can then see how it guides. Using the short focal length scope

to guide you will need almost 20 seconds or so to get the necessary

movement.



Hope this helps. More on the ST-4 at



www.abmedia.com/astro/articles/st4.html



Jim

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

From: "Scott Hammonds" shammonds@...>

To: ap-gto@yahoogroups.com>

Sent: Thursday, August 28, 2003 6:46 PM

Subject: [ap-gto] 400GTO Guiding Question





> Hi,

> I recently acquired a used 400GTO and have tried guiding the mount with my

> ST4 while piggy backing a camera for wide field shots.

> This is my first GEM and I most likely have multiple issues to deal with

> here.

>

> I believe my polar alignment was reasonably good, although I didn't spend

a

> great deal of time refining it. I know the ST4 is in good working order,

> I've had fairly good success guiding my LX200, at least as good as

possible

> with that setup. When I tried calibrating the ST4 I didn't get any

movement

> in the'x' axis using .5x or 1x rates set on the keypad. I tried changing

the

> rate to 64x and it did calibrate just fine, although it drove the star off

> of the chip and back on again during the calibrate process. With the ST4

in

> 'find and focus' mode I tried moving the mount using the keypad set at .5x

> or 1x and had to hold the keypad down for a fairly long time (5-7

se'conds)

> to even get 2-3 units of change on the ST4 readout.

>

> After getting it to calibrate at 64x I started guiding to see the results

> and it seemed to start fine, but the movement in the 'x axis gradually

> started climbing until it reached "e". The "y" axis had 0 to 2 in the

> readout. If I just left the mount in "find and focus" there was very

little

> movement in either the x or y axis for up to 5 minutes or so.

> At one point with the scope pointing straight overhead I had A0's to A1's

> for almost 5 minutes. Then later I was pointing about 30 degrees above the

> western horizon and the 'x' axis would climb gradually to 'e'.

> I was guiding through a 4" f5.4 scope and had a 35mm camera on the scope.

> Total weight approx 16lbs.

> I haven't had the film developed yet to see if the polar alignment was

off,

> it's E200 slide film and I'm out town in Florida for the Mars opposition.

> Currently the weather is not cooperating much either.

>

> I think the scope was properly balanced, but this is uncertain, since I'm

> going on little information.

>

> Any help or suggestions would be appreciated.

>

> Scott Hammonds

>

>

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>







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

#8438 Aug 28, 2003

Jim,

Thanks. I wondered if that might be an issue, I'll try that as soon as

practical.

I also may try a barlow to lessen that time.



Thanks for the link, but I've had that printed out for a long time and use

it as a reference. g>

I'll let you know the results.



Scott

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

From: "Jim Janusz" jjanusz@...>

To: ap-gto@yahoogroups.com>

Sent: Thursday, August 28, 2003 9:59 PM

Subject: Re: [ap-gto] 400GTO Guiding Question





> Scott,

>

> I suspect you did not get a good calibration. You should experiment with

> the C1 and C2 parameters. This parameter controls the time the ST-4 moves

> each drive axis during calibration. Calibration is necessary for the ST-4

> to learn the correction speed required, for your particular system to move

a

> star n number of pixels. You should calibrate each time you begin a

> photograph as calibration is sensitive to the sky location. I recommend

> that you experiment with how long a calibration time you can use without

> moving the star off the CCD or beyond 30 units. Start calibrating with

the

> star close to the CCD center. I recommend using whatever time produces at

> least a 10 count movement, because it seems to produce more accurate

> guiding. This is just intuition on my part.

>

> The AP mounts guide and calibrate just fine at 1x. Once you have a good

> calibration with the star returning to the starting point + or - about 2

> counts you can then see how it guides. Using the short focal length scope

> to guide you will need almost 20 seconds or so to get the necessary

> movement.

>

> Hope this helps. More on the ST-4 at

>

> www.abmedia.com/astro/articles/st4.html

>

> Jim

>

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

> From: "Scott Hammonds" shammonds@...>

> To: ap-gto@yahoogroups.com>

> Sent: Thursday, August 28, 2003 6:46 PM

> Subject: [ap-gto] 400GTO Guiding Question

>

>

> > Hi,

> > I recently acquired a used 400GTO and have tried guiding the mount with

my

> > ST4 while piggy backing a camera for wide field shots.

> > This is my first GEM and I most likely have multiple issues to deal with

> > here.

> >

> > I believe my polar alignment was reasonably good, although I didn't

spend

> a

> > great deal of time refining it. I know the ST4 is in good working order,

> > I've had fairly good success guiding my LX200, at least as good as

> possible

> > with that setup. When I tried calibrating the ST4 I didn't get any

> movement

> > in the'x' axis using .5x or 1x rates set on the keypad. I tried changing

> the

> > rate to 64x and it did calibrate just fine, although it drove the star

off

> > of the chip and back on again during the calibrate process. With the ST4

> in

> > 'find and focus' mode I tried moving the mount using the keypad set at

.5x

> > or 1x and had to hold the keypad down for a fairly long time (5-7

> se'conds)

> > to even get 2-3 units of change on the ST4 readout.

> >

> > After getting it to calibrate at 64x I started guiding to see the

results

> > and it seemed to start fine, but the movement in the 'x axis gradually

> > started climbing until it reached "e". The "y" axis had 0 to 2 in the

> > readout. If I just left the mount in "find and focus" there was very

> little

> > movement in either the x or y axis for up to 5 minutes or so.

> > At one point with the scope pointing straight overhead I had A0's to

A1's

> > for almost 5 minutes. Then later I was pointing about 30 degrees above

the

> > western horizon and the 'x' axis would climb gradually to 'e'.

> > I was guiding through a 4" f5.4 scope and had a 35mm camera on the

scope.

> > Total weight approx 16lbs.

> > I haven't had the film developed yet to see if the polar alignment was

> off,

> > it's E200 slide film and I'm out town in Florida for the Mars

opposition.

> > Currently the weather is not cooperating much either.

> >

> > I think the scope was properly balanced, but this is uncertain, since

I'm

> > going on little information.

> >

> > Any help or suggestions would be appreciated.

> >

> > Scott Hammonds

> >

> >

> >

> > To UNSUBSCRIBE, or for general information on the ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

> >

> >

> >

>

>

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>



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

#8439 Aug 28, 2003

I would not recommend the Barlow as it can cause the ST-4 to chase the

seeing if the fl gets too long. Try to stay around the fl you are shooting

at.



Jim

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

From: "Scott Hammonds" shammonds@...>

To: ap-gto@yahoogroups.com>

Sent: Thursday, August 28, 2003 7:16 PM

Subject: Re: [ap-gto] 400GTO Guiding Question





> Jim,

> Thanks. I wondered if that might be an issue, I'll try that as soon as

> practical.

> I also may try a barlow to lessen that time.

>

> Thanks for the link, but I've had that printed out for a long time and use

> it as a reference. g>

> I'll let you know the results.

>

> Scott

>

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

> From: "Jim Janusz" jjanusz@...>

> To: ap-gto@yahoogroups.com>

> Sent: Thursday, August 28, 2003 9:59 PM

> Subject: Re: [ap-gto] 400GTO Guiding Question

>

>

> > Scott,

> >

> > I suspect you did not get a good calibration. You should experiment

with

> > the C1 and C2 parameters. This parameter controls the time the ST-4

moves

> > each drive axis during calibration. Calibration is necessary for the

ST-4

> > to learn the correction speed required, for your particular system to

move

> a

> > star n number of pixels. You should calibrate each time you begin a

> > photograph as calibration is sensitive to the sky location. I recommend

> > that you experiment with how long a calibration time you can use without

> > moving the star off the CCD or beyond 30 units. Start calibrating with

> the

> > star close to the CCD center. I recommend using whatever time produces

at

> > least a 10 count movement, because it seems to produce more accurate

> > guiding. This is just intuition on my part.

> >

> > The AP mounts guide and calibrate just fine at 1x. Once you have a good

> > calibration with the star returning to the starting point + or - about 2

> > counts you can then see how it guides. Using the short focal length

scope

> > to guide you will need almost 20 seconds or so to get the necessary

> > movement.

> >

> > Hope this helps. More on the ST-4 at

> >

> > www.abmedia.com/astro/articles/st4.html

> >

> > Jim

> >

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

> > From: "Scott Hammonds" shammonds@...>

> > To: ap-gto@yahoogroups.com>

> > Sent: Thursday, August 28, 2003 6:46 PM

> > Subject: [ap-gto] 400GTO Guiding Question

> >

> >

> > > Hi,

> > > I recently acquired a used 400GTO and have tried guiding the mount

with

> my

> > > ST4 while piggy backing a camera for wide field shots.

> > > This is my first GEM and I most likely have multiple issues to deal

with

> > > here.

> > >

> > > I believe my polar alignment was reasonably good, although I didn't

> spend

> > a

> > > great deal of time refining it. I know the ST4 is in good working

order,

> > > I've had fairly good success guiding my LX200, at least as good as

> > possible

> > > with that setup. When I tried calibrating the ST4 I didn't get any

> > movement

> > > in the'x' axis using .5x or 1x rates set on the keypad. I tried

changing

> > the

> > > rate to 64x and it did calibrate just fine, although it drove the star

> off

> > > of the chip and back on again during the calibrate process. With the

ST4

> > in

> > > 'find and focus' mode I tried moving the mount using the keypad set at

> .5x

> > > or 1x and had to hold the keypad down for a fairly long time (5-7

> > se'conds)

> > > to even get 2-3 units of change on the ST4 readout.

> > >

> > > After getting it to calibrate at 64x I started guiding to see the

> results

> > > and it seemed to start fine, but the movement in the 'x axis gradually

> > > started climbing until it reached "e". The "y" axis had 0 to 2 in the

> > > readout. If I just left the mount in "find and focus" there was very

> > little

> > > movement in either the x or y axis for up to 5 minutes or so.

> > > At one point with the scope pointing straight overhead I had A0's to

> A1's

> > > for almost 5 minutes. Then later I was pointing about 30 degrees above

> the

> > > western horizon and the 'x' axis would climb gradually to 'e'.

> > > I was guiding through a 4" f5.4 scope and had a 35mm camera on the

> scope.

> > > Total weight approx 16lbs.

> > > I haven't had the film developed yet to see if the polar alignment was

> > off,

> > > it's E200 slide film and I'm out town in Florida for the Mars

> opposition.

> > > Currently the weather is not cooperating much either.

> > >

> > > I think the scope was properly balanced, but this is uncertain, since

> I'm

> > > going on little information.

> > >

> > > Any help or suggestions would be appreciated.

> > >

> > > Scott Hammonds

> > >

> > >

> > >

> > > To UNSUBSCRIBE, or for general information on the ap-gto list

> > > see groups.yahoo.com/group/ap-gto

> > >

> > > Your use of Yahoo! Groups is subject to

> docs.yahoo.com/info/terms/

> > >

> > >

> > >

> >

> >

> >

> > To UNSUBSCRIBE, or for general information on the ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

> >

> >

> >

>

>

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>







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

#8440 Aug 28, 2003

OK, I definitely know about chasing the seeing. The long focal length on my

SCT caused me a lot of grief until I used a reducer.

I'll keep what I have.



Scott Hammonds



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

From: "Jim Janusz" jjanusz@...>

To: ap-gto@yahoogroups.com>

Sent: Thursday, August 28, 2003 10:21 PM

Subject: Re: [ap-gto] 400GTO Guiding Question





> I would not recommend the Barlow as it can cause the ST-4 to chase the

> seeing if the fl gets too long. Try to stay around the fl you are

shooting

> at.

>

> Jim

>

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

> From: "Scott Hammonds" shammonds@...>

> To: ap-gto@yahoogroups.com>

> Sent: Thursday, August 28, 2003 7:16 PM

> Subject: Re: [ap-gto] 400GTO Guiding Question

>

>

> > Jim,

> > Thanks. I wondered if that might be an issue, I'll try that as soon as

> > practical.

> > I also may try a barlow to lessen that time.

> >

> > Thanks for the link, but I've had that printed out for a long time and

use

> > it as a reference. g>

> > I'll let you know the results.

> >

> > Scott

> >

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

> > From: "Jim Janusz" jjanusz@...>

> > To: ap-gto@yahoogroups.com>

> > Sent: Thursday, August 28, 2003 9:59 PM

> > Subject: Re: [ap-gto] 400GTO Guiding Question

> >

> >

> > > Scott,

> > >

> > > I suspect you did not get a good calibration. You should experiment

> with

> > > the C1 and C2 parameters. This parameter controls the time the ST-4

> moves

> > > each drive axis during calibration. Calibration is necessary for the

> ST-4

> > > to learn the correction speed required, for your particular system to

> move

> > a

> > > star n number of pixels. You should calibrate each time you begin a

> > > photograph as calibration is sensitive to the sky location. I

recommend

> > > that you experiment with how long a calibration time you can use

without

> > > moving the star off the CCD or beyond 30 units. Start calibrating

with

> > the

> > > star close to the CCD center. I recommend using whatever time produces

> at

> > > least a 10 count movement, because it seems to produce more accurate

> > > guiding. This is just intuition on my part.

> > >

> > > The AP mounts guide and calibrate just fine at 1x. Once you have a

good

> > > calibration with the star returning to the starting point + or - about

2

> > > counts you can then see how it guides. Using the short focal length

> scope

> > > to guide you will need almost 20 seconds or so to get the necessary

> > > movement.

> > >

> > > Hope this helps. More on the ST-4 at

> > >

> > > www.abmedia.com/astro/articles/st4.html

> > >

> > > Jim

> > >

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

> > > From: "Scott Hammonds" shammonds@...>

> > > To: ap-gto@yahoogroups.com>

> > > Sent: Thursday, August 28, 2003 6:46 PM

> > > Subject: [ap-gto] 400GTO Guiding Question

> > >

> > >

> > > > Hi,

> > > > I recently acquired a used 400GTO and have tried guiding the mount

> with

> > my

> > > > ST4 while piggy backing a camera for wide field shots.

> > > > This is my first GEM and I most likely have multiple issues to deal

> with

> > > > here.

> > > >

> > > > I believe my polar alignment was reasonably good, although I didn't

> > spend

> > > a

> > > > great deal of time refining it. I know the ST4 is in good working

> order,

> > > > I've had fairly good success guiding my LX200, at least as good as

> > > possible

> > > > with that setup. When I tried calibrating the ST4 I didn't get any

> > > movement

> > > > in the'x' axis using .5x or 1x rates set on the keypad. I tried

> changing

> > > the

> > > > rate to 64x and it did calibrate just fine, although it drove the

star

> > off

> > > > of the chip and back on again during the calibrate process. With the

> ST4

> > > in

> > > > 'find and focus' mode I tried moving the mount using the keypad set

at

> > .5x

> > > > or 1x and had to hold the keypad down for a fairly long time (5-7

> > > se'conds)

> > > > to even get 2-3 units of change on the ST4 readout.

> > > >

> > > > After getting it to calibrate at 64x I started guiding to see the

> > results

> > > > and it seemed to start fine, but the movement in the 'x axis

gradually

> > > > started climbing until it reached "e". The "y" axis had 0 to 2 in

the

> > > > readout. If I just left the mount in "find and focus" there was very

> > > little

> > > > movement in either the x or y axis for up to 5 minutes or so.

> > > > At one point with the scope pointing straight overhead I had A0's to

> > A1's

> > > > for almost 5 minutes. Then later I was pointing about 30 degrees

above

> > the

> > > > western horizon and the 'x' axis would climb gradually to 'e'.

> > > > I was guiding through a 4" f5.4 scope and had a 35mm camera on the

> > scope.

> > > > Total weight approx 16lbs.

> > > > I haven't had the film developed yet to see if the polar alignment

was

> > > off,

> > > > it's E200 slide film and I'm out town in Florida for the Mars

> > opposition.

> > > > Currently the weather is not cooperating much either.

> > > >

> > > > I think the scope was properly balanced, but this is uncertain,

since

> > I'm

> > > > going on little information.

> > > >

> > > > Any help or suggestions would be appreciated.

> > > >

> > > > Scott Hammonds

> > > >

> > > >

> > > >

> > > > To UNSUBSCRIBE, or for general information on the ap-gto list

> > > > see groups.yahoo.com/group/ap-gto

> > > >

> > > > Your use of Yahoo! Groups is subject to

> > docs.yahoo.com/info/terms/

> > > >

> > > >

> > > >

> > >

> > >

> > >

> > > To UNSUBSCRIBE, or for general information on the ap-gto list

> > > see groups.yahoo.com/group/ap-gto

> > >

> > > Your use of Yahoo! Groups is subject to

> docs.yahoo.com/info/terms/

> > >

> > >

> > >

> >

> >

> >

> > To UNSUBSCRIBE, or for general information on the ap-gto list

> > see groups.yahoo.com/group/ap-gto

> >

> > Your use of Yahoo! Groups is subject to

docs.yahoo.com/info/terms/

> >

> >

>

>

>

> To UNSUBSCRIBE, or for general information on the ap-gto list

> see groups.yahoo.com/group/ap-gto

>

> Your use of Yahoo! Groups is subject to docs.yahoo.com/info/terms/

>

>

>







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