Hey Daniel, Here is the verbiage and calculations on the device: http://www.hubbleoptics.com/artificial-stars.html It recommends the telescope be placed at a distance based on two formulas. M=336*D/F^3 where D is in inches. Distance = M*D*F The 12" mead is 12" aperture, f/10. I came up with 483.8" = 40.3 ft. I'll re-read the instructions and check the calculation. You guys know the physics of optics much better than I. I'll have to bend your ear(s) this year at the sun and star parties. I want to learn more. I took the eyepiece out of the diagonal and moved it back until I got focus on the 57 ft distant tree. The eyepiece was a good 5"-6" off the diagonal. Hahahaa! So it is pretty far out if focus. Guess the easy collimation out the window is not possible and I'll have to disassemble the scope and set it up in the yard some night when we have a clear night. Listening to the weather report, that's not going to happen this week! Bruce
Bruce:
40 feet doesn't sound right to me, but my only reference is Suitter and he is looking at Newtonians.? and he is doing more >than just collimation.? Perhaps, just for collimation you don't actually need to come to focus.? Just centering the blob will >suffice.
DT