Where to buy/scrounge a small converging lens?

[BetterSense]

I need a simple 20-25mm diameter (slightly larger can work if it's plastic) lens with a 40-50mm focal length. It's for a lightmeter I'm building. I'm just having a hard time finding anywhere online or in the real world where I can buy such a simple lens element.

 

[Terence]

Did you try www.surplusshed.com ? They appear to have several.

Go to the categories menu on the left of their main page and select the lens finder.

 

[BetterSense]

No, I'll try it out. Allelectronics has several but not the right ones.

edit: Wow, they have every sort of lens.

 

[Hamster]

How about lens/viewfinder from a disposable camera or a box camera, it is a bit smaller bit might work. If a complete lens block is ok for you then those 40/2.8 objectives/viewfinder on cheap 70s compact might work too.

 

[steven_e007]

Try an optician that makes their own spectacles. Some of them have a little 'factory' on the premises. See if they will let you have a lens blank. These are about 40cm diameter. You'll need a 20 dioptre convex lens with no prism or cylinder.

 

[Steve Smith]

I'm sure I have one somewhere. If you can't get one locally, let me know by PM and I will post one to you.


Steve.

 

[BetterSense]

Suplusshed had exactly what I was looking for. I was able to buy several 20mm diameter, 50mm focal length DCX lenses and a 20mm diameter, 17 mm focal length, for $4 each.