lens openings for old 8X10 lensgreenspun.com : LUSENET : Large format photography : One Thread
I have an old lens that came with a "Standard" 8X10 view camera made by Rochester Opyical Co. It is a #3Hemispherique Rapid. made by B.F.& Co Darlot Paris.It has a slot in it to slide in vanes each with a different size hole to be used for different apetures. Does anyone know where I might be able to buy some of these? Also, where would be a good place to have this lens cleaned. TIA, Ron
-- Ronald Boudrieau (firstname.lastname@example.org), May 21, 2001
Hope you'll be interested in this:
-- Geoffrey Chen (DB45TEK@AOL.COM), May 21, 2001.
The last old barrel lens I bought needed some waterhouse stops and I made them out of a couple of old 4x5 darkslides I had laying around from junked film holders. The two hardest parts of making them was getting the right shape so that they fit into the lens barrel correctly and drilling the hole in the very center. In order to get the right shape, I used a tool used for copying moulding profiles and things of that sort- a bunch of thin metal rods next to each other in a holder that allows you to press it up against something and read the profile off of it. I inserted it into the slot for the waterhouse stops, traced the curve, and made the stops accordingly. I found the center to drill on by trial and error, basically. Figuring out the proper diameter for each hole was easy enough....using the proper optical formula (which I can't remember at the moment). As far as cleaning is concerned, if it isn't a complex optical formula or a particularly valuable lens, it's relatively easy to disassemble, clean, and reassemble a lens. Good luck.
-- David Munson (email@example.com), May 21, 2001.
If you can spare $100, SK Grimes is certainly the way to go. If you are going the DIY route, try McMaster Carr for black phenolic plastic. I believe it's sold under the trade name Garolite. You might also try making stops from brass if you have a drill press and larger size bits designed for safely cutting brass. You might even try black matboard, although its harder to cut a precision hole in paper-based material (try 220 grit sandpaper). To determine the diameter of each stop, divide the focal length of the lens by the standard set of f-stops (f22, f16, f11, f8, f5.6 etc.). If your lens has a focal length of 12 inches, for example, and you divide 12 by 16 (f16) you get a diameter of .75 or 3/4". Obviously, some of these calculations will not match standard drill bit sizes (12 divided by f22 equals .54, slightly larger than a 1/2 inch). As a result, you may end up with with numbers like f24 and you may need to even out the difference when you make your exposures. This is not a big deal especially if you are using a Packard shutter or exposing negatives by covering the lens with a lenscap. One other note: I would measure the "clear aperture" of the lens (no stops) to determine the f-number of the lens wide open. Many older lenses give interesting results at wider apertures and some portrait lenses are even designed to be used in this fashion. Hope this helps.
-- Dave Willison (firstname.lastname@example.org), May 22, 2001.