Eyepiece and telescope pairing

Connecting a camera to the Sky-Watcher Classic 200P (8-inch Dobsonian)

The exact thread or barrel that lets a camera reach prime focus on the Sky-Watcher Classic 200P (8-inch Dobsonian), and the adapter that makes it work.

Telescope interface
2 in focuser (no rear-cell thread); a T-adapter noses into the focuser
Adapter needed
a 2 in prime-focus (nosepiece) T-adapter, plus a camera-brand T-ring
Camera-side thread
T-thread (M42 x 0.75), via a camera-brand T-ring
Prime-focus focal length
1200 mm (f/5.9)
No fit

Not for prime-focus imaging. The Sky-Watcher Classic 200P (8-inch Dobsonian) reaches a camera only through its 2 in focuser with a nosepiece T-adapter, but a manual Dobsonian base does not track, so long-exposure prime focus is impractical. It is a visual and short-exposure lunar scope.


A camera reaches a telescope's prime focus through a T-adapter that matches the telescope's interface on one side and the standard T-thread, M42 x 0.75, on the other. A camera-brand T-ring then bayonets to the body.

Unlike a Schmidt-Cassegrain, this design has no threaded rear cell, so the camera mounts through the focuser drawtube. Check that the focuser has enough inward travel to reach focus with the mirror or sensor where a camera sits.