When PEC is active does it work even if no autoguiding?

[gregbradley]

I was wondering if PE corrections are active and affecting the mount on a PMX when no autoguiding is being done. Or does it only work when the autoguider is operating?

I somehow had the idea PEC only worked when autoguiding but reading the manual it says "turn this checkbox on to apply periodic error during sidereal tracking."


Greg.

[Mighty_oz]

When PEC is on it's always on, works if u tick the box, i've found helps somewhat if it's good hinders if not well done :) For the PMX
Marcus

[Geoff45]

I'm pretty sure that when you enable PEC, it is applied and has nothing to do with whether or not you are auto guiding. Indeed, if you want to do unguided exposures it would be a bit of a bummer if PEC didn't work.

[gregbradley]

Thanks for the replies. I don't where I got that idea from but it appears it is applied as soon as you check the apply box.

That plus ProTrack could mean long exposures without autoguiding and round stars if perfectly polar aligned. That could be very convenient especially if the seeing is bad or its partially cloudy.

Greg.

[Mighty_oz]

LOL, well that is what we hope for, yet to see it myself but others here have done so and so u can as well. I hope so ! Looking forward to your results.

[gregbradley]

I did a 5 minute exposure last night with PEC on and Protrack activated on a 44 point model (SB Says 50-200 point model). EBadly elongated stars at 1050mm focal length.

I discovered later in the night my mount was out of balance at that time by quite a bit so not a good test.

I did not end up doing a 200 point model as there were some clouds and then it cleared and it would have eaten into my limited imaging time and I was already getting nice round stars so little incentive.

I also tried it on my PME with about a 100 point model and it did not work at 3 metres focal length.

Its worth taking it further though.

Greg.

[frolinmod]

Flexure is so bad with my OTA that I can't even do unguided exposures at all without ProTrack engaged. Turning on ProTrack makes a huge difference here.

[gregbradley]

I can see that. The model would be predicting all the flexes.
My AP140 has zero flex. The 4 inch focuser tube is stainless steel which is hard and strong as.

Greg.

[frolinmod]

Oh yeah, a nice strong refractor! Drool. My "flex-o-matic" is an EdgeHD 14 OTA. And I don't mean mirror flop or slop. Just the OTA by itself is floppy.

[gregbradley]

Still 3 metres is a great focal length for nice close up galaxy images.
The AP is a dream scope though for its aperture.

Greg.

[Merlin66]

Which mount and dovetail are you using on the 14"???
I have a C11 on a Losmandy dovetail hanging on a NEQ6pro and can easily hold a target star on the 25micron spectroscope slit almost indefinately......

[frolinmod]

I'm using an Andy Homeyer Scope Cradle (http://www.intint.com/andy/build.html) bolted directly to the Versaplate of a Paramount ME. Without ProTrack enabled I get about a one arcsecond per minute drift (unguided). With Protrack enabled I get almost no drift (unguided). The difference is dramatic.

[Merlin66]

Looking at your quoted results I'm not sure why you would have said "Flexure is so bad with my OTA that I can't even do unguided exposures at all ....."
I wouldn't think a 1 sec movement would indicate severe flexure!

[Poita]

I don't know if it would help, but you can buy a carbon fibre tube for the C14.

[Paul Haese]

Just getting back to the original question, PEC when enable is always on. If you use it in conjunction with pro track you should be able to do unguided subs of 5-10 minutes easily on a long focus scope so long as you pointing model is large enough.

[gregbradley]

These reports are encouraging. I'd like to take that further.

Greg.