PEC Training

[Starwiz]

Can anyone tell me how I go about recording a PEC curve.

I can find tutorials on how to use the curve, but not how I get it in the first place.

I'm using PHD2 and EQMOD.

Thanks

John

[Budgie1]

Have you had a look through the VS_PEC workflow documentation on the EQMOD site?

I had a play with this on my last imaging session but it wasn't successful because I tried recording the PE during the imaging session, which included dithering. Of course, dithering creates unwanted movement which throws off the PE being recorded. So don't dither while recording PE.

[JP-S]

Interesting point about the dithering, I was wondering how that affects things myself. Is it possible to filter dithering using pecprep I wonder?

Otherwise I found this video useful: 

 

[Budgie1]

29 minutes ago, JP-S said:

Interesting point about the dithering, I was wondering how that affects things myself. Is it possible to filter dithering using pecprep I wonder?

Otherwise I found this video useful: 

 

I watched that video last week and that's what made me look into it further. My EQMOD doesn't have the functions to transfer the PPEC to the mount though, I  don't know if this is something to do with the my HEQ5 not being able to record it to the motors like the EQ6 can or whether I'm missing an add-on?

As for pecprep filtering the dither errors, hard to say because you would need to run a few recordings to input to pecprep for it to average out the sine-wave. I think I'd rather pick a night with high cloud, when I can still see bright stars but it's no good for imaging, and do a recording for an hour + without dithering. Then see what sort of curve I get like that.  

[MarsG76]

Hi John,

I played with PEC on my CGEM a couple of years ago and even though I got it working, I didn't find the difference to be substantial enough to be worth while when autoguiding through an OAG and PHD2. The slightly lower correction and RMS figure could easily have been better seeing... That said, perhaps unguided imaging would see a benefit?

MG

 

[Clarkey]

I shared the same experience as John above. I did try using predictive PEC on both my mounts but found the benefits very minimal - if any. I ended up using the PPEC option in PHD2 which does seem to give a benefit after it has run for a while.

[alacant]

18 hours ago, Starwiz said:

PHD2 and EQMOD.

Hi

+1 as @Clarkey and @MarsG76

We tried the built in eqascom vs-pec on a windows system but to no avail.

The best way to deal with PE we found was to tear the mount apart with careful cleaning, re-greasing and adjusting. Even better after replacing the bearings, even on new mounts.

When the mount is as perfect mechanically as you can get it, then it's worth guiding RA via PPEC. Our sweet spot was with a fixed period of 122s; one of the harmonics on the motor gear, but try initially with the full worm rotation at 480s. Maybe out-of-the-box mounts would benefit too? Perhaps less so than a clean example.

HTH

 

Edited May 11, 2021 by alacant

[MarsG76]

Also have a read of my PEC experience... now this might be a coincidence but worth noting as it did happen...

 

https://stargazerslounge.com/topic/336050-my-cgem-mount-sudden-death/?tab=comments#comment-3657266