Hi,
At last I could do a test of the mount during environment I had control over.
I did a simple auto guiding test with PHD2 and got a tot rms error of 0.69". I',m sure I can tweak it to be better than that later.
Here are some screen dumps with graphs:
http://www.astrofriend.eu/astronomy/...ebuilding.html
Long time ago I had even lower rms error, something like 0.5" to 0.8", in that time I had an off-axis adapter, same EQ6 mount but no belt drive.
A lot of people say they could auto guide with a guide telescope with shorter focal lengths, as low as 1/4 of the main telescope.
My main telescope has 910 mm FL and the guide telescope has 400 mm FL. The pixel size is smaller in the guide camera (QHY5 mono chrome) but not very much difference compare to the Canon 6D pixelsize. I have no IR block filter on the guide camera so the focus is really soft. But that doesn't look to be a problem, it's more that it even out pixel to pixel differences.
What are your experience from guide / main telescope focal length relation ?
/Lars