[bedted (Tim)]

Hey there everyone, this seems to be a fantastic forum and I've already found some valuable information. I've been dabbling in astrophotography after my purchase of a 300mm lens and teleconverter a few months back.

I built a simple barn door mount and have managed to successfully track and stack 1 minute exposures at 35mm (full frame 5D). Turning by hand.

But not surprisingly the barn door mount doesn't work as well with the 300mm lens and TC (effective 420mm).

So now I'm considering where to head next.

I can either invest some time in motorising my current barn door mount, or purchase a ready made solution like the AstroTrac TT320X-AG.

The question is, at over 300mm focal length, exactly how difficult will it be to get acceptable tracking (>1 min subs) motorising the barn door mount?