Vignetting with Atik 314/200P DS combination

[Robfal]

Calling all Newtonian imagers!

I've recently acquired a Atik 314L+ and currently setting it up. When I connect it to my skywatcher 200P DS Newtonian (imaging version) I can clearly see what appears to be vignetting in images. The wasn't apparent with the Atik 16ic I used before however this does have a much smaller chip.

Should I be getting this vignetting (or is it coma) with my combo? Is there anything I can do to solve this?

I have used the trial version of CCD Inspector and the scope is well collimated. However should I be adjusting the secondary mirror? Unfortunately I didn't save any images however I will post a flat ASAP. I will also fit the Atik to the ED80 and see if there is still a problem.

All suggestions welcome

Rob

[Robfal]

Now fitted the atik to the ED80 and there is no vignetting. So what is the solution? Is the something I should do in the optical train or can this be corrected through the use of flats

Rob

[ollypenrice]

It seems odd that a small chip like the Sony 285 should show vignetting. You'd be snookered with a DSLR!

Vignetting is a darkening around the edges of the chip, coma a comet-like elongation of the edge stars.

It couldn't be coming from your eyepiece adapter? How is the camera fitted to the scope? In a fast scope you might need a 2 inch nosepiece. I have never imaged with a scope like yours so I don't know.

Olly

[Robfal]

I agree Olly. I am surprised that there is a distinct lightening of the image to the one side. That's why I question that I've got the optical chain correct.

Atik 314L

M42 thread

Atik Filter wheel (with 1 1/4 filters)

M42 thread to focusser

Currently got it on the ed80 but I'll transfer it back and then get a photo. Equally I'll get an image (probably a flat frame)

Regards

Rob

[Coco]

Must be the optical train, Deneb (Nadeem) didn't have issued with his DSLR and this scope as far as I remember..

[Deneb]

With a DSLR & a coma corrector on this scope without a 50mm extension which in not needed anyway, I had no issues..

Nadeem.

[ollypenrice]

Odder and odder. It couldn't be a light leak or sky gradient?

Olly