[Spookyer (Brett)]

Hi all

I finally got around to trying my Nikon lenses to do some widefield with my SBIG STT8300 camera and filterwheel. To use a lens with this camera you need to use the standard filterwheel cover rather than the self guiding filter wheel cover and you need a lens adapter.

First off I got nothing but stars because the aperture of modern Nikon lenses are actually closed when off the Nikon body. I had to put a little piece of plastic in the aperture slot to keep the aperture wide open on the SBIG camera.

I tried my 24-70 2.8 full frame lens. The image posted is 24mm and is a crop of the bottom left of the image (about 1/8th of the image), the center of the actual full image is better but the rest is a shocker. It is like that all around the outside third of the image. I tried it at 50mm and 70mm and got similar results.

I am not sure what is happening. I believe I am following the recommendations correctly for this camera and I purchased the standard filter cover and the adapter from SBIG for this purpose so perplexed as to what I might be doing wrong. This a full frame camera lens that works on a full frame sensor that is much bigger than the 8300 chip in the SBIG. I would have thought only the centre of the lens would actually be in use.

The images are unguided but the mount is good and the sub short so it is not a guiding issue, at 24mm you can get away with a fair bit and the centre of image is not so distorted.

Any thoughts on what is going on?

Brett