PEC Training With DSLR

[The-MathMog]

Hey Guys.

I was just wondering if it is possible for me, to do PEC training using my Nikon DSLR and the cables that I got? I don't have a guiding setup yet, and I want to wait until the money is there and also getting more used to imaging. I tend to have a very good polar alignment, as the image doesn't drift through each frame, but rather there is a "jerk" or drift every other frame, when doing 2-3 minute subs. I guess that is periodic error, as it happens even on windless nights.

So, I have both my Nikon DSLR and my mount hooked up to my pc (the mount through port in the Celestron Advanced VX Controller), from which I can send slew commands. I have the periodic error correction tool too, but as of right now it seems that I have to monitor and correct any PE myself, which I honestly don't want to do as doing that 8 minutes straight with precision doesn't sound easy. So can I hook up the DSLR through say PHD2 and let it correct for me, and do the PEC training, or do I need the actual cable that goes into the Guider port of the mount? Any thoughts on if this is possible would be well received! And if not, I guess I'll either just need to get used to shorter subs (or throwing 1/2 of them away), or trying to do the training manually with the zoomed image of Backyard Nikon..

Cheers

-Mathias

[newbie alert]

I have the same mount..also do 2-3min subs (2 min subs with a 8sct,and 3 mins with a 80mm frac) the only subs i throw away is if i have a plane through the fov.. not every other frame..i doubt it's pec..  could be a power or connection issue..as I had some issues with a power tank, and the connection with the lead/mount connector..both caused it to do strange things..

How do you polar align? With a polar scope? Sharpcap,postmaster? Do you use the align mount feature on the handset?

[The-MathMog]

Mounts and worm gears are not created equally. So some mounts might have more errors in the gears than others. I can do 3 minute subs too, but the timing between subs I have to scrap is quite consistent with my understanding of worm gears and their period (something like 8 minutes?), hence why I can capture more shorter exposures before having to scrap one. I also use a barlow, with the field of view of 0.7x0.4 degrees so with a big dslr sensor, it is quite sensitive to small changes, which these are.
I am connected to the power socket with a good quality cable.

I first align manually, looking at charts where Polaris needs to be in the fov of my 32mm ep. Then I use the mounts ASPA, and lastly I do a few quick drift aligns, which also shows those subtle jitters. If is was an error in polar alignment, then the drift would be consistent, and it isn't at all. So I am still very convinced that it is PE

So PEC training is something I want to do no matter what, I just need to figure out if it's possible with my equipment that isn't guiding compatible.
 

[MARS1960]

I'm new to this but are you sure you have good balance? a (good) AVX mount shouldn't do that, even my 10 year old CG5 GT would do 2min subs all night with maybe half a dozen throw aways.

[The-MathMog]

It is balanced as good as my abilities allow, with a slight east-heavy side. I've also ordered home some Tube-rings, as the ota I am using was normally mounted on an Alt-Az mount, and was a bit one-side heavy in declination, but to my knowledge that wouldn't matter much. You need to know that I am also using a 2.25x barlow to allow focus, basically making it around 1450 in focal length, which also amplifies any small error in tracking, wind gusts and or PE's. And the mistakes I am talking about here, are small enough, that I wouldn't notice them, if I DIDN'T use that barlow. If I didn't use it, I'd most likely keep most of my frames. But that's another thing I'll fix in the future. Not completely convinced yet, that it isn't PE

But no matter what, I still want to figure out if I am able to do PEC Training with a DSLR, which is the only reason I made the topic, whether the current mistakes are balance, polar, or anything else related  As I still don't own a guiding-cam+scope.

[MARS1960]

14 hours ago, The-MathMog said:

It is balanced as good as my abilities allow, with a slight east-heavy side. I've also ordered home some Tube-rings, as the ota I am using was normally mounted on an Alt-Az mount, and was a bit one-side heavy in declination, but to my knowledge that wouldn't matter much. You need to know that I am also using a 2.25x barlow to allow focus, basically making it around 1450 in focal length, which also amplifies any small error in tracking, wind gusts and or PE's. And the mistakes I am talking about here, are small enough, that I wouldn't notice them, if I DIDN'T use that barlow. If I didn't use it, I'd most likely keep most of my frames. But that's another thing I'll fix in the future. Not completely convinced yet, that it isn't PE

But no matter what, I still want to figure out if I am able to do PEC Training with a DSLR, which is the only reason I made the topic, whether the current mistakes are balance, polar, or anything else related  As I still don't own a guiding-cam+scope.

Ok, i see your point, you can train with any camera providing the software is adequate, a free trial of BYEOS should do the job, substitute the eyepiece for your camera and use BYEOS, hope this helps.

Training. During this phase you use the control panel or menus to say "Hey! Pay attention to this!" to the mount, then you manually keep a star perfectly centred for several worm periods. You do this by centering a star with a high-magnification eyepiece that includes a cross-hair reticle. You then stare at the star for 10 to 15 minutes and use the mount's hand controller to manually make the small adjustments necessary to keep it perfectly centred on the cross hair. The mount records the error corrections you supply, remembering where in the worm position each one was needed. By training through more than one worm cycle, the mount can record an average correction, in case you reacted slowly or over-reacted.

Playback. Once you have trained the mount, you can turn on PEC. The mount will "play back" the recorded error correction information by slightly changing the speed of the Right Ascension drive to move ahead or back each time your manual error corrections did the same. This will cancel the periodic error, resulting in a smoother track.

1. Training. During this phase you use the control panel or menus to say "Hey! Pay attention to this!" to the mount, then you manually keep a star perfectly centred for several worm periods. You do this by centering a star with a high-magnification eyepiece that includes a cross-hair reticle. You then stare at the star for 10 to 15 minutes and use the mount's hand controller to manually make the small adjustments necessary to keep it perfectly centred on the cross hair. The mount records the error corrections you supply, remembering where in the worm position each one was needed. By training through more than one worm cycle, the mount can record an average correction, in case you reacted slowly or over-reacted.
2. Playback. Once you have trained the mount, you can turn on PEC. The mount will "play back" the recorded error correction information by slightly changing the speed of the Right Ascension drive to move ahead or back each time your manual error corrections did the same. This will cancel the periodic error, resulting in a smoother track.

[The-MathMog]

6 hours ago, MARS1960 said:

Ok, i see your point....

Thanks a lot man. I will give it a go, the next time the clouds allow it, as I do have BackyardNikon!