Zeiss Triotar 21cm f/3.5

<p>A few weeks ago I asked in this forum if anyone had ever heard of a Zeiss Triotar 210mm f3.5 lens built for 35mm Exakta cameras. None of you had (nor have any of the people who run the various Exakta websites). I e-mailed the nice historians at the Zeiss archive, who (within about 24 hours) replied that the glass was produced around 1925-1926. It is item #1588 in the virtual museum and looks to be part of a 3.5 series made for large format cameras, of which 21cm is the upper limit. </p>

<p>That leaves the lens barrel, which seems to have been custom-made outside of Zeiss, but I can't find any branding inside or out. I have made a list of the things that I do know about the lens, and would greatly appreciate any help with the questions that follow:</p>

<p>1. The front glass does not rotate when the lens is focused. Does anyone have any pre-wwii lenses that have this, versus front glass that rotates? All of my pre-war glass rotates, but all I have are relatively basic Leica rangefinder lenses. Do any of you have pre-war Exakta-mount lenses whose front elements don't rotate? </p>

<p>2. The aperture scale is marked 3.5, 4.5, 6.3, 9, 12, 18, 25, 36. Does anyone have an idea of a date at which the standard changed to the more modern 3.5, 4, 5.6, etc.? Usually this seems to be an indication of pre versus post-war in lenses like 50mm Elmars (and their Soviet clones), but I'm not sure about other companies. I know that I have a Kodak 70mm lens from the 1930's that follows the latter standard.</p>

<p>3. The tripod socket built into the lens is 3/8" - by what point had most companies switched to the 1/4" standard?</p>

<p>4. The focus scale is in meters (marked 2.5 to infinity). I guess this points to European origin and might rule out Burke and James...? </p>

<p>5. I can't tell what kind of metal the barrel is made from, but it feels more like aluminum than brass (brass just has that warmer feel and heft to it; I can't quite explain it). When did aluminum come into common use in camera (and other) stuff?</p>

<p>6. The lens mount is an interior mount for Exakta, not the external mount often used for longer/heavier lenses that JDM mentioned in my prior post.</p>

<p>Thanks for any ideas anyone has. </p>

<p>Here are some pictures:</p><div></div>

<p>.</p><div></div>

<p>..</p><div></div>

<p>I guess enough time has passed to make it unlikely you're posting more. Thank you. I love to see these things.</p>

<p><em>Kadlubeks Objektiv-Katalog</em> doesn't seem to list this, but their way of dividing up Zeiss production makes it difficult to be sure,</p>

<p>They do show a 13,5 cm Triotar (IHG 1020 and 1030), but no 21 cm.</p>

<p>Did you try the MF focus lens forum for information, just a thought</p>

<p>Wow a 210 3.5, three element lens, that would be something wide open. Love to see some shots with it, especially at full aperture.</p>