Ed Huntress fired this volley in
:

Have you actually tried this with such a small reflector, Lloyd? I've
been a magnifying-glass fire bug since I was 7 or 8, and here's my
experience with it:

Of course I have, Ed! I think nobody ever taught you how to properly
light a fire with a lens! Burning lens 'pocket' kits for the purpose of
starting fires were available even in Colonial times.

Weren't you paying attention in class when we described the little Radio
Shack cigarette lighter? It has only a small fraction of the area of a
6" mirror (only about 3" x 4-1/2" oval), and will reliably light a weed
in the noonday sun.

FWIW, Ed, I've been making telescopes since I was 13. I don't ever
remember a single objective (refractor or reflector) that didn't get at
least ONCE tested as a 'burner'... just because I could. I also don't
remember a single mirror or lens larger than about 2" that wouldn't serve
the purpose. That 12" F-6 I made was quick to make a sheet of plywood
burst into flame, but I've lit fires with 25-cent plastic dimestore
magnifiers. I have a survival kit fresnel lens firestarter with a
rectangular size of only about 2" x 3".


Hell! I'd probably go to jail for doing such today, but when I was about
15, I made a "solar timer" that would ignite something at a particular
time of day (albeit only if the sun shone). THAT took some planning!
You can't just move the sun to test your aiming point!


Lloyd