This Questar 3.5 rides as guide scope on a Celeston 9.25, with an Imaging Source firewire camera connected to an old Macbook, running PHD guiding software. It was much darker than the image appears, shot with a Nikon D700 and a 24mm lens at ISO 5000 for 25 seconds. Taken in a light polluted Milwaukee suburb.
I used this setup to shoot the dim planetary nebula M-76.