Quote:
Originally Posted by g__day
So you're guiding on the 80mm or 66mm refractor and imaging on the C9.25?
I typically have the calibration step around 400ms or lower and the min pixel before pulse guides are sent around 0.75 - 1.1 pixels (seeing, pixel size and focal length dependent).
That last point causes folk alot of grief I believe. If your seeing is poor, and a star covers alot of very small pixels you don't want to in effect over sensitise PHD. Ron Wodaski (google) has an online pixel calculator that can be used to assess how much of the sky (arc seconds) each pixel of your guide camera is seeing and whether you should be binning pixels to form a super pixel. Its pointless over driving the sensitivity of the guide camera when seeing is poor.
Can you confirm which camera is on what scope - that they are firmly mounted to reduce differential flexure and mention the focal length of your guide scope and the pixel size of your guide cam?
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Ah, sounds like I have over-sensitive settings that are being affected by seeing...that would explain the guiding OK sometimes and then not if it is seeing dependent.
As for which scope, I use every combination (or will do)... e.g. 66mm to guide camera on my 80mmED (most common), 66mm to guide the C9.25 with reducer, C9.25 to guide and camera through the 66mm, guiding with the 80mm and piggy-back lens on top (next most common).
I have rock solid guide rings and mounting. I'm confident that flexure is not an issue.
cheers,
Rob