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Possible to train PEC with autoguider instead?

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#1 Taylor

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Posted 27 July 2009 - 01:38 AM

In reading on the PEC training procedure for my Sphinx's Starbook, and I assume any other modern EQ Mount, I have to manually guide on a star for 8 minutes (preferably with an illuminated reticle for accuracy).

Instead of doing this procedure, can I just hook up an autoguider to it and autoguide the PEC on a star for the most accurate recording?

#2 Gama

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Posted 27 July 2009 - 03:37 AM

I would look at using PemPro. You have 60 days trial free, and well worth the money.
It will map out your PEC, then create a PEC curve to fix your errors, then upload it to the mount.

You can also just use your ccd to do the PEC as well, but no where as good.

Theo

#3 blueman

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Posted 27 July 2009 - 12:56 PM

Hi,
I have used the autoguider to train PEC and it worked fine. Pempro would probably be the better choice, I just purchased it myself, but this method will work. I would suggest you set the exposure frames at 3-5 seconds to avoid chasing seeing however.
Blueman

#4 Taylor

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Posted 27 July 2009 - 07:49 PM

Thanks for the recommendations. There's no way I'm paying $150 for software to train a feature in my mount that I'll use maybe a few times a year. I may trial it for a bit but definitely not buying.

#5 freestar8n

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Posted 27 July 2009 - 08:53 PM

Hi-

Your main question was - can you autoguide instead of manually correcting when recording PEC - and the answer is definitely yes. I don't know any benefit of doing it manually. Just get your autoguiding tuned well, and have the mount pretty well polar aligned so there is little dec. drift - and then record the PEC for playback. It is advisable to average many worm turns somehow if possible. I don't know what software options you have to do that with your mount, though. Celestron mounts have a free tool called PECTool that does it. There may be similar options for your mount.

Frank

#6 Taylor

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Posted 27 July 2009 - 11:50 PM

Thanks Frank, you answered what I needed to know.

#7 Mike Clemens

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Posted 27 July 2009 - 11:51 PM

PemPro is genius... averaging a large number of curves, autocorrecting for drift. I corrected my mount with the trial, and bought it to say THANKS RAY THAT WAS EXCELLENT !!

#8 Gama

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Posted 28 July 2009 - 08:29 AM

Just need to remember one thing when using a CCD to do corrections for you in PEC. There is a small delay from the time the star moves to the time the corrections have been completed. Its not just milliseconds as your normal reflexes operate. But the time of exposure, download, process, re-act, send command, respond.. And all over again
This delay adds to your dilema, so instead of fixing PEC, it may extend it. Some programs allow you to time shift a little so as to align the actual PEC with the correction.
Remember, PemPro is free for 60 days, so use it and never worry about it again.

Theo

#9 chicot

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Posted 28 July 2009 - 08:55 AM

I agree with the consensus of opinion on Pempro. It is excellent. I bought it and have never regretted it. It also comes with a very useful polar alignment wizard as well. As the others mentioned, you get a 60 day free trial so you have absolutely nothing to lose by giving it a try.

#10 freestar8n

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Posted 28 July 2009 - 09:00 AM

I use video-based guiding with MetaGuide, which I wrote and is free. For PEC training you can use a bright star at perhaps 30 fps. You can then centroid based on perhaps 10 video frames for an effective exposure of 300ms. The time from mid-exposure to the delivery of the correction is basically half the exposure time because there is negligible overhead in the video delivery or processing - amounting to a net delay of 150ms. If these corrections are made every 1s, they should be pretty well in phase with what the mount is doing. They are fine at removing the fundamental and harmonic from my CGE. The RA response to corrections, with a slightly imbalanced mount, is very fast.

If you train with long exposures and each image has a second or more download time - I agree there would be problems and the eye/hand might be better.

Frank






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