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 Post subject: Advice on PEC. Recording and using.
PostPosted: Sun Dec 07, 2014 5:03 pm 
Hi all,
I've been trying to find out how to record and use PEC but there is a lack of basic info on the web, or am I asking the wrong questions!
I've got a William Optics ZS71 sat atop a iOptron ZEQ25 mount and I'd like to try using a PEC file to overcome some of the long term wobbles. The iOptron manual is of no help at all. I assume I need some sort of wide field scope, a camera and software to record the wobbles over one rev of the worm. Am I right? Some internet respondents say to "just press the Record button on the handset". Somehow I don't think this is the full story. Others suggest webcams, short scopes and PHD; this seems OK as far as it goes. As the PEC is a one-shot file (iOptron does not store it in the handset on power down) why can't I use the William optics as the scope, my Canon 600D as the camera and record the PEC that way? Software will convert any star deviations into motor speed corrections and produce a file. Right or wrong? Then I play back the file from the handset during the imaging sequences. If it is possible to do that why does none of the software I've looked at appear to be able to connect with a DSLR? How would I get the PEC file into the handset to enable the 'Play' feature. I must be missing something?
iOptron talks about recording the file by going down the full autoguiding route but then tells me that I can't use PEC and autoguide at the same time. I am confused.
Any advice welcome,
Thanks, Eb


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 Post subject: Re: Advice on PEC. Recording and using.
PostPosted: Sun Dec 07, 2014 8:23 pm 
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Joined: Thu Jun 14, 2012 5:46 pm
Posts: 99
Location: Little Lever
Have you tried posting in the yahoo group, I've found them very helpful with my MTP

https://groups.yahoo.com/neo/groups/ioptron/info

or here and you can pm Paul Chasse 'astronewb' beta testing for iOptron

http://www.astronomyforum.net/ioptron-telescope-forum/

I'm sure someone will help you out

or this guy, he's a lot closer to home, I know its a different model mount but he might be able to explain 'how to'

http://www.thewilmslowobservatory.org/i ... error.html


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 Post subject: Re: Advice on PEC. Recording and using.
PostPosted: Sun Dec 07, 2014 10:33 pm 
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Joined: Mon Oct 12, 2009 8:27 pm
Posts: 376
Location: Adlington
Eb,
Pec works by replaying a set of pre-recorded corrections. What you suggest might sound logical but it doesn't work that way around. So you have to be guiding ie issuing corrections during the recording phase. Some can average several sets of corrections which is better.
However pec works best with smooth repeatable drives (not with wobbles) and can enable unguided exposures. I would suspect that your z25 probably needs autoguiding continuously so pec will be of little or no advantage. I gave up with pec years ago - autoguiding is the way to go and corrects what is really happening.


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 Post subject: Re: Advice on PEC. Recording and using.
PostPosted: Mon Dec 08, 2014 3:20 pm 
Hi David,
thanks for the info. I'm still left wondering why I cannot record a worm cycle using my imaging scope rather than a similar but cheaper one, and then replay the recorded whilst I actually do the imaging. The actual mechanics of how it's done, though, is still a mystery. I do take your point that if you've got to do a full autoguide setup to record a PEC then what's the point of PEC in the first place.
Cheers for now,
Eb


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 Post subject: Re: Advice on PEC. Recording and using.
PostPosted: Mon Dec 08, 2014 4:35 pm 
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Joined: Mon Oct 12, 2009 8:27 pm
Posts: 376
Location: Adlington
Eb,
The standalone software PemPro does indeed work as you imagine. However, it does not use a DSLR - an 18 megapixel image is a bit of overkill for watching a single star. Instead a webcam or guidecam is more practical. However, Pempro does not appear to support Ioptron - this could change with version 3. Pempro can analyse your mount but not upload a correction file.

It is some years since I used it but below should be the Pempro pec data for my mount. The red line is the Pempro best fit curve - the red dots are the actual readings over 8 cycles. These are all over the place due to the Lancashire seeing and are worse than the periodic error! So I didn't bother.


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