--- In LXD75telescopes@yahoogroups.com, "Kurt Massey" <quack_youll@y...> wrote:
>
> Periodic Error Correction, Every time the drive worm for the RA goes
> around there is a little bit of error, either too much travel or not
> enuff, this function corrects for that. You set it by starting with
> a very good polar alignment, High power retical eyepiece. find a
> star close to what you want to image, then hit Pec record and guide
> the scope. Then when you start imaging, you play PEC and it repeates
> the corrections you made to correct tracking error. BUt its still
> not as good as autoguiding.
For those who owns LXD55 and LXD75
below is a comment from lxd75 yahoogroups, which vince is a member, but may be of interest to others here:
-
tanguan2001
- Posts: 146
- Joined: Fri Oct 10, 2003 10:06 pm
- Location: Braddell
- Contact:
Guys,
The best way to cut down time needed for drift alignment is to set up in the same place every time! I have marks made (with crayon) on my driveway for this, so I set up the tripod legs in the same place everytime. Even then, though, drift alignment can take 1 hour or so.
Having set up the tripod, I mount the camera (in my case DSLR), aim at a star near the meridian, focus, and take a low res shot (uploaded to the computer) every 15s to monitor drft N-S. I then adjust the orientation of the whole tripod until there is minimal drift. Then repeat for a star near the eastern horizon to adjust elevation - this is usually very quick if you have drift aligned before and don't touch the mount elevation after.
To do photography, unless you guide, there is no choice. PEC won't help unless you align accurately. If your image scale is 1 to 2 arcsec/pixel its amaving how much drift there is in even 15s unless the alignment if very good.
I train PEC using a SAC7 (webcam) autoguided using Astrosnap (could also use Iris). On the GPX and SS2K the PEC training is retained between sessions unless you slew manually with the power off - I try not to do that - it's a hassle to have to train again.
At the moment with a GPD, drift alignment and PEC, I'm able to go to 90s unguided exposures. Even then about half the shots are trailed and have to be discarded - may have to tweak the mount some more!
TG
The best way to cut down time needed for drift alignment is to set up in the same place every time! I have marks made (with crayon) on my driveway for this, so I set up the tripod legs in the same place everytime. Even then, though, drift alignment can take 1 hour or so.
Having set up the tripod, I mount the camera (in my case DSLR), aim at a star near the meridian, focus, and take a low res shot (uploaded to the computer) every 15s to monitor drft N-S. I then adjust the orientation of the whole tripod until there is minimal drift. Then repeat for a star near the eastern horizon to adjust elevation - this is usually very quick if you have drift aligned before and don't touch the mount elevation after.
To do photography, unless you guide, there is no choice. PEC won't help unless you align accurately. If your image scale is 1 to 2 arcsec/pixel its amaving how much drift there is in even 15s unless the alignment if very good.
I train PEC using a SAC7 (webcam) autoguided using Astrosnap (could also use Iris). On the GPX and SS2K the PEC training is retained between sessions unless you slew manually with the power off - I try not to do that - it's a hassle to have to train again.
At the moment with a GPD, drift alignment and PEC, I'm able to go to 90s unguided exposures. Even then about half the shots are trailed and have to be discarded - may have to tweak the mount some more!
TG
Yes...but as you know, we guys in Spore don't normally have this luxury of able to set up at the same place all the time.tanguan2001 wrote:Guys,
The best way to cut down time needed for drift alignment is to set up in the same place every time! I have marks made (with crayon) on my driveway for this, so I set up the tripod legs in the same place everytime. Even then, though, drift alignment can take 1 hour or so.
TG
Unless living in landed property, the chances of able to do that is very slim.