I have had good success in imaging from a DOB. mine is a 12" 1500mm FL. The DOB are mostly used for viaual observing so the focal point is deeper than a camera. To solve this I screw the primary lens closer to the secondary and then collimated.
The focus travel was then within range. To get good close ups I then made an equatorial platform for motion control as free hand worked but not well.
My favourite image from the DOB was
M42
and best planetary from the DOB is
Jupiter
and lunar done with a webcam
https://goo.gl/photos/qPz9FGanWvNtPdB77