I am having issues imaging with my DSLR camera: fainter objects do not even appear in my photos. My current setup is a 6" 1216mm Meade Starfinder (f/8) with a Telrad and my camera is a Nikon D5300 mounted using an Orion combined camera adapter with an H20mm lens.
The issue is I don’t seem to be gathering sufficient light. I can view stars that are bright and visible to the naked eye and image them through my camera. My camera is properly focused and that I can see the bright stars I was imaging. But when attempting to image any other object (M31 for example) my camera is completely dark. I have my camera in manual mode and have tried tweaking both my ISO and exposure with no apparent improvement. From what few images I have been able to take there appears to be some chromatic aberration in the stars. I am quite new to Astrophotography (at least with a dobsonian) and therefore may have a flawed setup to begin with. Below I have attached a picture I took of Sirius (It's not the best).
I'm not sure if it's a mechanical or an electronic issue that is causing me a lack of light but I would appreciate any advice. Thanks!