I've been playing with glass....

[John Kasaian]

...attempting to cobble together some home made lenses, one of them being a rather large meniscus. My problem is mounting the beast. IIRC the Kodak portrait lens was a meniscus and was located behind the stop with a darken tube in front of the stop.While I can get tubing with the id to accomodate this lens, I've got to figure out if the lens should go behind the stop (like Kodaks) or in front---or if it even matters!
Any suggestions?

[Gary Beasley]

I've notice other simple cameras with meniscus lenses having the stop out front. I'd bet theres a reason for that optically. Have you got any way of testing it before making a permanent installation?

[Hollis]

There is a book that should help you out - very interesting...

http://www.amazon.com/Primitive-Phot...4615724&sr=1-1


Primitive Photography by Alan Greene

[Peter K]

Also when the distortion of a lens is corrected for distant subjects, it is normaly not corrected for near subjects. The diaphragm is such a close-up subject. So to avoid pincussion distortion the diaphragm should be normaly in front of the lens. But only in special cases one can correct barrel distortion with a diaphragm behind the lens.

[Murray]

In agreement with what Peter K said, very old cameras had the stop in front of the meniscus lens for better distortion performance.

Modern disposable cameras do the opposite. I have seen some old (50's-60's?) camera patents that had other-than-flat film planes, even slightly cylindrical. They had a combination of factors to correct the distortion adequately. Some were also not using meniscus lenses, however.

I would stick with the aperture-in-front method for the simplest camera construction.

I think the Greene text referenced and an old Dallmeyer patent both mention some rules of thumb for lens diameter and stop-lens distance.

1/7-1/5 of the f.l. for the lens diameter and stop spacing. Exactly where one measures from on the glass I don't know. Dealing with 'found glass' that wasn't ground to your specs, one can't always meet both.

[Daniel_Buck]

I've messed with creating lenses. For some of my lenses, I just taped them (around the edges) to a cardboard 'lens board' that has a hole in it. Fixed aperture, but it work.