From: Christopher Lovenguth (zantzant@hotmail.com)
Date: 03/11/03-02:19:04 PM Z
Hi all, it's been awhile since I've thought about this and can't remember
how to do it. I'm looking at buying an old barrel lens that doesn't have any
markings on it and I can't get to it to see it in person. I've seen pictures
of it and it's very very very low in price so I'm willing to take the chance
of buying it without seeing it. However I want to try to figure out what the
lens f-stop is first.
The person selling it thinks it's a 16inch lens that is 4 1/2 inches long
and 3 inches diameter across the front.
With that info is it possible to estimate an f-stop or do I need the
diameter of the back of the lens as well?
Have any of you seen old brass barrel lenses that were higher then F8
anyway? I would prefer something 5.6 of under because I'd be using this for
making daguerreotypes. Anything over F8 forget about it, we're talking 30min
to an hour in full sun to get an image.
Here is a link to a picture of the lens, highly unlikely since it's only a
side view but maybe someone will recognize it. Plus does anyone know what
that slit is for? Is this one of those lenses that you used to drop in an
aperture and if so can it be used without them?
http://www.chrisportfolio.com/upload/lens/
it's the barrel lens.jpg on that page
Thanks in advance,
Chris
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