Big cheap lenses for bright little LEDs

My Arc AAA ultraviolet -- and presumably any LED light -- when shined through a big old surplus projection lens I have sitting here will make a very tight bright beam that lights things up 20 feet away in a spot about palm size.

I'd been looking for cheap surplus projection lenses to use as cheap macro lenses -- but this is more fun.
http://www.surplusshed.com/list.cfm?Category=Lenses

-- the one I'm playing with here is similar to the $10 Delta lens on that page.

Oh lordy, I just used the lens in front of the USB Flylight and it projects a beautifully focused 1 foot diameter image of the actual LED on the wall six feet away. I can see the leads, the intense bright violet center surrounded by yellow (no wonder I was thinking there was some UV in this one, it's quite clear when projected).


No need for a 4" diameter lens for one LED but I wonder what it'd do in front of a light cannon .... I'm going to go back and look for smaller diameter projection lenses and microscope lenses.

I wonder if there's a forum for lens addicts I need to join ...

Sounds interesting.
I have hundreds of surplus (broken) binocular and rifle scopes which in turn generate a good number of lenses each.
I must go through them and see which work the best.
Pity I am the other side of the world otherwsie we could make a plan to get some to you.

I have a home-brewed version of the ledcorp belt-lite. It works with a fresnel lens and puts out a fantastic beam. Any fresnel lense suppliers out there?

Weird, I just happened to search for Fresnel lenses yesterday, but for a different reason - melting/burning stuff.

For cheaper Fresnel lenses (may not be the right size for a flashlight though, probably better for melting/burning stuff ) try: http://www.ultraoptix.com/magnifiers/fresnellens.html

For higher quality, more sizes, but more $, try: http://www.edmundoptics.com/IOD/DisplayProduct.cfm?Productid=2040
or: http://www.fresneltech.com/ http://www.fresneltech.com/pdf/FresnelLenses.pdf

They both have quite a few small diameter lenses (around 0.6" to 5") that might work well for a flashlight.

Hope this helps,
Andre

A good source for lenses is old copiers and such. Check with a copier supply place and see if they have any junkers they have taken in trade. Another place is disposable cameras. Stop by a photo processing place and ask if they have any. Also a good source of flash tubes.

This place has some cheap, small lenses.
http://www.sciplus.com/category.cfm?subsection=21