Widefield imaging with camera

[ianpwilliams]

I was considering trying a bit of widefield imaging using my HEQ5 Pro SynScan mount with my 1100D attached to the mount via a dovetail and adaptor that I have.

Assuming I get a reasonable polar alignment, I take it that it would then just be a case of using the handset to point the camera at a random patch of the sky (no doubt the milky way), and then doing some long subs? After all I wouldn't be able to do 1-star alignment.

Also, would I be best zooming in using the standard 22-55mm lens (or whatever it is), or being fully zoomed out?

Also, what kind of sub lengths should I expect to reach at minimum and maximum zoom?

Also, would it be worth doing darks with the lens cap on (there's no way I would do flats)?

And I assume it would be worth taking multiple subs and stacking them?

Also, am I likely to get any kind of decent results under light polluted skies?

[MilwaukeeLion]

Have you considered piggybacking telescope?  I don't have answers but some sub length info that might help.  I can get decent stars with 1-2 min subs @ 120mm piggybacked on my 5" sct alt az just two star aligned.  You should get much longer better subs than my set up.  I think JMI piggyback mount was $50 or so but looks like I could've made it for $10.  I've had problems stacking with clouds, trees and such but im sure experts on here who know how.  Maybe stack sky not ground then match it up.

[pipnina]

I was considering trying a bit of widefield imaging using my HEQ5 Pro SynScan mount with my 1100D attached to the mount via a dovetail and adaptor that I have.

Assuming I get a reasonable polar alignment, I take it that it would then just be a case of using the handset to point the camera at a random patch of the sky (no doubt the milky way), and then doing some long subs? After all I wouldn't be able to do 1-star alignment.

Also, would I be best zooming in using the standard 22-55mm lens (or whatever it is), or being fully zoomed out?

Also, what kind of sub lengths should I expect to reach at minimum and maximum zoom?

Also, would it be worth doing darks with the lens cap on (there's no way I would do flats)?

And I assume it would be worth taking multiple subs and stacking them?

Also, am I likely to get any kind of decent results under light polluted skies?

I managed to image M31 and an arm of the milky way during a full moon with street lamps glaring in the camera lens, you just need to know how to remove gradients. I had 8 mins of exposure.

Multiple subs = yes!!! I like kappa-sigma stacking best.

With my camera, I can't use the lens at the widest FOV due to distortions (in canon this will likely be worse if your camera doesn't have distortion correction like nikons) and vignetting. I have to stop down by 2/3 stops from max and zoom half way in to get the most out of it.

I live in moderate LP... But 30 second subs at f5.6 only gets about 1/4 of the way through the well depth. I suspect that, unless your LP is pretty bad, 2 minutes won't be pushing it too far (but star masks would be a good idea as brighter stars tend to get washed out.

I prefer to point it at a specific target (e.g. a constellation or a large nebula/galaxy) and get some good framing around it. Otherswise your image may not contain much else than stars!

Good luck!

    ~pip

[ianpwilliams]

The only issue with piggybacking is that if I'm going to go to the trouble of setting up the telescope, star aligning etc then I would feel like I might as well just image something through the scope.

And I was hoping that I might be able to have subs a lot longer than 2 minutes due to the wide FOV, but maybe not.

And I think you're right about aiming at a target (M31 or M42 being the obvious choices), otherwise it would just be stars. Although it may just end up being stars anyway. I think for truly amazing wide field you probably need a dark site or something.

I have just ordered a guide cam and scope in an attempt to do guided imaging, so maybe if and when I get the hang of that then I could later try guided widefield piggybacked imaging with the camera.

[wxsatuser]

Does'nt matter what lens, focal length, iso or f ratio the best exposure for your sky brightness is

in the range of 20 to 40% of the in camera histogram.

Set everything up and take test exposures so the peak of the histogram reaches at least 20%.

Adjust for slightly longer exposures upto a maximum of about 40%.

Here is a ten minute exposure under moderate LP with a CLS clip filter.

The histogram peak is approx 25%.

[Knight of Clear Skies]

You should be able to get longer subs than 2 minutes with a kit lens, I've managed three-and-a-half at 50mm successfully.

Gradients are going to be your biggest problem at the wide end of the lens if you're imaging from a light polluted area, I've had more success at 50mm and 135mm fl when imaging through moderate lp.