4.5" American Optical lens
Posted 02 December 2012 - 02:25 PM
Posted 02 December 2012 - 07:17 PM
Threading a pipe could be costly. Why not find a sonotube of the right diameter or a rolled hastings pipe and put that it? You could friction fit it or drill and tap a few holes in the lens cell.
Posted 02 December 2012 - 07:49 PM
Consider some kind of plastic pipe fittings for a tube. Both tube and the fittings can be used. Example a sched 40 PVC pipe (nom 4") has an OD of 4.5 inch. A coupling will have a 4.5 inch ID and fit over a 4 inch "pipe". A pipe end cap with a 1.25 inch hole drilled could be the push-pull eyepiece holder.
How much color do you get looking thru it? How big are the stars?
The above is a thought that likely costs (significantly) less than $50.
Posted 02 December 2012 - 08:26 PM
Posted 03 December 2012 - 01:53 PM
Make up a zero-cost test rig to assess performance first! For completeness sake, try the lens in both orientations. See how high a power you can achieve before image 'softness' becomes objectionable. Beware daytime testing, where your eye's pupil will act as an aperture stop when it's smaller than the exit pupil.