This photograph of Andromeda highlights a major issue I have been having with deep space photography. I am taking this photograph as an example because it is taken at the zenith, with the thinking that there would not be all that much atmospheric refraction. Yes, I am aware of the piece of grass or hair that got in the photo.
- Camera: Nikon D5100
- Exposure time: ~5 minutes
- Telescope: Sykwatcher EvoStar 100ED (refractor)
- Mount: Skywatcher EQ6-R Pro
- Eyepiece: Badaar Morpheus 17.5mm Eyepiece
I do not have any other equipment yet, so no active star tracking with a separate camera. I also am only using two adapters to connect up to the camera. No extenders between the camera and the eyepiece are being used.
When I did my star alignment with the camera, I did notice the stars tended to deviate slightly, after a few seconds, from the center of the live view. If this was the cause though, I would have expected my Andromeda image to have unidirectional smearing, not radial light diffraction. I noticed a similar problem when I was trying to fine tune my focus with a star. I had slight, but noticeable radial light diffraction around the star, which I had centered on my screen.
I should also note that, the diffraction looks less on my Orion Nebula photograph and I only exposed it for about a minute. But it was also near the horizon when I took it, and I have not yet done anything with color filters. Also, the diffraction is not present when I visually observe, skipping the camera.
Any idea what might be causing my images to look like this, and any possible solutions?