VintageBigBlue.org

 

Re: [Losmandy_users] Re: PEC on G-11


Nov 11, 2000

 


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

#939 Nov 11, 2000

I understand that the PE on these mounts is very low out of the box,

say +/- 12 arc seconds. This is okay overall, but with long exposure

CCD imaging, this could be a problem. I guess that's why many people

modify their G-11's.



I understand however, that the G-11 does have periodic error

correction, but I have been unable to find any information on what

the capability of the PEC on this mount is even though it does have

it. I did read one review by a user that said it is non-existent and

basically worthless on this mount which must be an exaggeration.



I am about to move up from my present setup to a Celestron 9.25 SCT

and want it on a GEM. The G-11 seems to be the one based on its

popularity, but I am not interested in spending $2000, and then

basically having to re-build the mount (or at least replace stock

bearings with better bearings) to achieve better tracking accuracy.

It would seem to me, that if the PEC were implemented in the proper

fashion, there would be less of a need for these types of

modifications. Does anyone have any specific information on the PEC

for the G-11 and what has been your experience? Thank you for your

time and input.



David



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

#940 Nov 11, 2000

The actual PEC function does work, but the implementation of it on the

standard digital drive system leaves a lot to be desired. .



Once trained, you cannot use the fast slew rates, only the slow guide modes

to move the telescope. So if you want to center or slew to a target after

PEC training on a bright nearby star, forget it.



And turning PEC off (to slew for instance) loses the previous training.



I found it unbearable to use.



Regards



Eddie Trimarchi

~~~~~~~~~~~~~~~

www.fan.net.au/~eddiet







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

From: djones@... [mailto:djones@...]

Sent: Sunday, 12 November 2000 6:31 AM

To: Losmandy_users@egroups.com

Subject: [Losmandy_users] PEC on G-11





I understand that the PE on these mounts is very low out of the box,

say +/- 12 arc seconds. This is okay overall, but with long exposure

CCD imaging, this could be a problem. I guess that's why many people

modify their G-11's.



I understand however, that the G-11 does have periodic error

correction, but I have been unable to find any information on what

the capability of the PEC on this mount is even though it does have

it. I did read one review by a user that said it is non-existent and

basically worthless on this mount which must be an exaggeration.



I am about to move up from my present setup to a Celestron 9.25 SCT

and want it on a GEM. The G-11 seems to be the one based on its

popularity, but I am not interested in spending $2000, and then

basically having to re-build the mount (or at least replace stock

bearings with better bearings) to achieve better tracking accuracy.

It would seem to me, that if the PEC were implemented in the proper

fashion, there would be less of a need for these types of

modifications. Does anyone have any specific information on the PEC

for the G-11 and what has been your experience? Thank you for your

time and input.



David







To unsubscribe from this group, send an email to:

Losmandy_users-unsubscribe@egroups.com



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

#942 Nov 11, 2000

David:

but I have been unable to find any information on what > the capability of the PEC on this mount is even though it does have

> it.



Go to www.losmandy.com and look under support (I think). The users

manual is on-line and describes the PEC function. I think it says

that you can expect about 30% fewer corrections with PEC. Mainly,

it's for manual guiding. If using a CCD autoguider, leave the PEC

off.

Essentially, you manually guide at high power for 4 minutes (one

worm cycle) then the PEC duplicates the corrections you made with the

same periodicity after that. It's only for RA, and once engaged, you

lose high speed slewing. As Eddie T. said, it's somewhat of a pain,

but if manually guiding, it will make a difference.



Regards,

Bruce Inscoe



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

#946 Nov 12, 2000

--- In Losmandy_users@egroups.com, djones@j... wrote: > I understand that the PE on these mounts is very low out of the

box, > say +/- 12 arc seconds. This is okay overall, but with long

exposure > CCD imaging, this could be a problem. I guess that's why many

people > modify their G-11's.

>

> I understand however, that the G-11 does have periodic error

> correction, but I have been unable to find any information on what

> the capability of the PEC on this mount is even though it does have

> it. I did read one review by a user that said it is non-existent

and > basically worthless on this mount which must be an exaggeration.

>

> I am about to move up from my present setup to a Celestron 9.25 SCT

> and want it on a GEM. The G-11 seems to be the one based on its

> popularity, but I am not interested in spending $2000, and then

> basically having to re-build the mount (or at least replace stock

> bearings with better bearings) to achieve better tracking

accuracy. > It would seem to me, that if the PEC were implemented in the proper

> fashion, there would be less of a need for these types of

> modifications. Does anyone have any specific information on the PEC

> for the G-11 and what has been your experience? Thank you for your

> time and input.



I found the only way to 'see' if the PEC function worked was to input

a very large 'correction' and watch to see if it played that back in

four minutes or so. When trying to use PEC for normal visual

tracking, I couldn't see any reduction in the input corrections

needed. I feel the PEC is next to useless, especially as you loose

the ability to slew the scope once it's enabled.



Using mostly CCD autoguiding means I don't manually guide anymore, as

the autoguider can correct periodic errors without using the mount's

own PEC.



Dave







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

#947 Nov 12, 2000

If you can't see the pec difference on a G-11 then you probably aren't

guiding at a hi enough power.



Try 250 or more



Jimmy

>From: "David Johnson" egroupecu@...>

>Reply-To: Losmandy_users@egroups.com

>To: Losmandy_users@egroups.com

>Subject: [Losmandy_users] Re: PEC on G-11

>Date: Sun, 12 Nov 2000 08:45:52 -0000

>

>--- In Losmandy_users@egroups.com, djones@j... wrote:

> > I understand that the PE on these mounts is very low out of the

>box,

> > say +/- 12 arc seconds. This is okay overall, but with long

>exposure

> > CCD imaging, this could be a problem. I guess that's why many

>people

> > modify their G-11's.

> >

> > I understand however, that the G-11 does have periodic error

> > correction, but I have been unable to find any information on what

> > the capability of the PEC on this mount is even though it does have

> > it. I did read one review by a user that said it is non-existent

>and

> > basically worthless on this mount which must be an exaggeration.

> >

> > I am about to move up from my present setup to a Celestron 9.25 SCT

> > and want it on a GEM. The G-11 seems to be the one based on its

> > popularity, but I am not interested in spending $2000, and then

> > basically having to re-build the mount (or at least replace stock

> > bearings with better bearings) to achieve better tracking

>accuracy.

> > It would seem to me, that if the PEC were implemented in the proper

> > fashion, there would be less of a need for these types of

> > modifications. Does anyone have any specific information on the PEC

> > for the G-11 and what has been your experience? Thank you for your

> > time and input.

>

>I found the only way to 'see' if the PEC function worked was to input

>a very large 'correction' and watch to see if it played that back in

>four minutes or so. When trying to use PEC for normal visual

>tracking, I couldn't see any reduction in the input corrections

>needed. I feel the PEC is next to useless, especially as you loose

>the ability to slew the scope once it's enabled.

>

>Using mostly CCD autoguiding means I don't manually guide anymore, as

>the autoguider can correct periodic errors without using the mount's

>own PEC.

>

>Dave

>

>

>

>

>To unsubscribe from this group, send an email to:

>Losmandy_users-unsubscribe@egroups.com

>

>

>



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