Help Identify Brass Wollensak Lens

<p>I acquired this lens with a Rochester Improved Empire State 8x10. No other markings except Wollensak and patent dates of Feb 6, 1900 and Jul. 23, 1901. In an Automatic shutter (1-100). Elements are just about 1.5" diameter, and length from rear glass to front is about 2.5".<br>

Any suggestions as to specific model name ? </p><div></div>

<p>Widest aperture is marked 4</p><div></div>

<p>Put the lens on the camera, open the shutter, set the aperture to f4, move the standard(s) until you achieve infinity focus then lock the standards. Measure from the ground glass to the aperture blades, this is the approximate focal length.<br>

Look at the 1903 Wollensak catalog at camera eccentric,<br>

<a href="http://www.cameraeccentric.com/html/info/wollensak_12.html">http://www.cameraeccentric.com/html/info/wollensak_12.html</a> ,<br>

as it has the shutter listed. The lens can be hand held and focused to infinity in a dim lit environment with the lens pointed at a brighter area such as a window but it is not as easy or as accurate as the camera. A piece of cardboard can be used for a temporary lens board if needed.</p>

<p>My gut feel would be a <a href="http://en.wikipedia.org/wiki/Rapid_Rectilinear">Rapid Rectillinear</a>. That's very typical of f/8 lenses. The inside of each cemented group would be concave, the outside convex, and only three reflections.<br>

Also consistent with the rather wide spacing of the front and back groups.<br>

If you count four reflections on each side, it's likely to be a <a href="http://en.wikipedia.org/wiki/Dialyte_lens">Dialyte</a>, a symmetric design. They are often somewhat thinner than this lens. Many of the earlier f/7.7 Kodak Anastigmats are Dialytes.</p>

<p>The lens is probably a Rapid Rectilinear of about 12" focal length. The aperture scale follows the US system where US4=f8, US16=f16, US128=f45, and so on.</p>

<p>Fantastic ! Thanks everyone. That link to the 1903 catalog is a huge help, too.</p>

<p>If the front glass is only 1.5 inches, the longest the focal length can be is 6 inches. The focal length is the "apparent" diameter of the aperture as seen through the front of the lens times the f stop. If the lens is only 1.5 inches in diameter and the largest aperture is f4 that would be 1.5 inches x 4, or 6 inches max.<br>

If the lens does turn out to be a 12 inch lens when you test it, it will indicate that Maris Rusis is correct and its using the US scale and the largest aperture is actually f8. 1.5 inches x 8 = 12.</p>

<p>I just picked up this lens (or one very similar to it) as part of an old agfa 8x10 camera kit. I can't for the life of me figure out how to open the shutter for focusing. It may be that something is not working correctly (or user error, of course) but I don't see any lever to open the shutter, as I've had on my graflex and more recent cameras. The shutter itself works fine and the bulb and timed speeds open the shutter as long as I hold the release down, but that doesn't seem too practical. Any suggestions greatly appreciated</p>

<p>Brian</p>

<p>Update: I think I've answered my own question after reading some of the articles here: use the Bulb setting to open the shutter and "lock the plunger". </p>

<p>The only question I now have is how to "lock" a pneumatic-style plunger. I don't see any way to attach a mechanical plunger to this shutter?<br>

Thanks again on any suggestions</p>

<p>Brian</p>