Re:, ATM: Very small bad mirrors

["David Harbour" <scarab2@cox.net>]

To all:

I knew a guy who made an EXCELLENT, rather than bad, very small mirror. He
bought, from his local dispensing optician, an unprocessed opthalmic blank
(for those of you not in the know, this is just a little lens waiting to be
edged to the correct size and shape into an eyeglasses lens).

All of these little blanks (somewhere between two to three inches in
diameter) have a concave, and a convex side. He sent it to an aluminizing
company with instructions to aluminize the concave side. It was beautiful.
If anybody wants to make a small reflector this way, specify to the
dispensing optician that you want an opthalmic blank that has the least
amount of "reflex" in it- that is to say, specify that you want the
"flattest", but still bent, opthalmic blank. I hope I have made myself
clear, here. Also, you can make a decent long focus refractor with one of
these, stopping it down a little. Specify focal length in "diopters" so that
the dispensing optician will understand which one to sell you. And specify
glass, not plastic. Glass is still available.

There is a world of things that one can do with these little blanks; I made
my binoculars into "macro binoculars" by mounting two of these little blanks
(.25 diopter) on little sleeves to fit over the end of each half of my
binoculars- can watch praying mantises, spiders, other small wildlife up
close without having to get close to them. My friend's little tiny opthalmic
blank reflector mirror formed beautiful, tiny little images. I also made a
super macro telephoto lens, 800mm focal length, for my SLR camera, using
Sparco mailing tube, that would focus as close as 8 feet.

These little opthalmic blanks sell for around $20 apiece, here.

Davey