Re: ATM Telephoto lenses as a small portable telescope...

[astillma@nit.AirTouch.COM (Anthony Stillman)]

Jeff,

I turned a 500mm catadioptic lens into portable telescope for business trips.
I made the ocular holder by casting it in two part plastic with black coloring.
I filed and sanded it afterward.  The hole was formed by carving a candle to a bit
over 0.965 inches in diameter then waxing  it into the center of the mold (a plastic cup.)

I stuck some press adhesive green felt on the inside of the cast piece for
the oculars to slide against.  I mounted the plastic ocular holder to the lens
by attaching the mounting ring I removed from a broken camera to the plastic
piece.  This was actually the hardest part as I had to cut a groove in the plastic
piece I had cast to match where the mounting ring had a projection. (yea, yea I
know, file it down, have you any idea how hard that metal they make thoses rings out of 
is?)  As the erzats telescope came with a 1/4-20 thread on it, mounting was
a sinch on my plop out tri-pod.   I would have missed most of the the Shoemaker impact 
series if not for this scope.  I don't use it that much anymore, but what
does astronomy have to do with telescope making anyway?

I indended to right the image (more than just an erection, aham I mean image
eractor as this is a catadioptic) by extending the focal plane with a negative
Hastings triplet (barlow), but I haven't gotten to it yet.

Anthony

no more resistor jokes please