View Full Version here: : Attempting to capture PEC Data

15-08-2017, 07:55 PM
Evening All.

I'm trying to capture some PEC data using PHD2. Everywhere I read about capturing PEC data says to make sure Guiding is switched off, yet I can not find an option anywhere to do that.

Am I going insane? What am I doing wrong? What's the best way to capture PEC data for PECPREP using PHD2?



15-08-2017, 08:11 PM

Click the "brain" icon, then go into the Guiding tab. Down the bottom left there's a checkbox which says "Enable mount guide output" - that's the one you're looking for. Unchecking that disables guiding.

15-08-2017, 08:13 PM
Best way is to do it inside EQMOD if you can.

Set the two filters up a bit - say about 1/5 and 1/3 across respectively, then record at least 4 worm cycles.

Repeat later if need to adjust further. Works really well in the later versions of EQMOD.

15-08-2017, 08:34 PM
Thanks Lee, That's exactly what I was too blind to see, Sorry about the dumb question.
Rob, I will definitely have to try that. Is that using AutoPEC?
Am I right in assuming I can image and capture PEC Data at the same time? And this will be better quality data than PHD Guide Logs?


15-08-2017, 08:57 PM
Yes, autoPEC.

The downsides of doing AutoPEC though:

- you have to make sure PHD keeps guiding indefinitely (e.g. no pausing, or dithering if you're integrating it with something else like Sequence Generator - unless you run very long exposures like say 1 hour)

- I find I have to increase the filter settings a bit to smooth out the resulting PE curve.

Its probably worth going through the PECPrep workflow a couple of times just to understand how the high/low/magnitude filters work and get a feeling for what sort of curve and PE you have to deal with.

16-08-2017, 09:49 AM
Thank you for all your help.
I managed to capture something last night. Does this look reasonable?
Am I on the right track?

Side question, anyone here heading up to Astrofest this Friday?

Thanks again

BTW Mount is an EQ8


16-08-2017, 10:07 AM
Wow, if that was done with autoguiding off you have a great EQ8. Almost doesn't need PE correction.

16-08-2017, 12:14 PM
That was just the output from AUTOPEC. Does this tell me nothing? I will try the PHD log tonight.


16-08-2017, 12:36 PM
Definitely worth doing it via PHD so you have more confidence in both methods.
My guess is that's PE curve is representative however - the EQ8s seem to be great mounts in general - much larger gears for a start.

16-08-2017, 10:01 PM
Just did about 10 cycles of my EQ8 and captured the data using PHD2 (Guiding Off)
This graph looks a lot more realistic - but the resultant PEC says I should have a residual of about 2.3 arcsecs, which sounds pretty good to my uneducated ears.

Here's the graph for the interested


Thanks for your help. Onwards and upwards... continuing to capture data for my first foray into NB imaging (Eagle Nebula)