Quote:
Originally Posted by Merlin66
Andrew,
Probably around 220mm focal length.
You could take an image and plate solve to get an accurate result,
Something like ASPS -http://www.astrogb.com/astrogb/All_Sky_Plate_Solver.html
Or simply remove the camera and point the finder at the Sun, use a piece of card to find best focus image and measure the distance from the objective to the card.
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I tried that and it was ~180mm; fed it into phd2 and it gave me calibration steps of ~2000ms. A previous problem was that calibration failed as star didn't move enough; will see how this goes when next we get a clear night...
Andrew