Turner-Reich Apertures

[Captain_joe6]

Hey all,

I've got my hands on a 12-21-28 Turner-Reich triple convertible, in a Betax #4 shutter, and engraved with the old US aperture scale. I know that the 12" focal length is f/6.3 (by the current standards), but what I need to know is how do I treat the aperture scale for the 21" and 28" lengths? Do I mentally move everything over a couple of notches? I figure that the 21" length is about f/11 and the 28" is about f/16, but where does that make the other stops fall? Does it throw everything out of calibration, or do I just treat each number on the scale as a correspondingly higher value (ie, if I use the 21" and it is f/11, and I set the aperture at the widest open, which is now f/11, is the next mark on the scale right at or close enough to f/16 to work?)

[Justin Cormack]

You should just be able to add the number of stops. Remember that aperture is just ratio of focal length to diameter of the hole - you can check by measuring!

[Glenn Thoreson]

You're lucky to have marked stops of any kind. I have a Conley Anastigmat triple comvertible with rotating Waterhouse stops. They aren't marked at all. Nor are the converted focal lengths. Now, THAT'S frustrating.

[Captain_joe6]

So you're saying that if the 12" is f/6.3-f/64, then the 21" is f/11-128 and the 28" is f/16-f/180? Or will it be f/180 Once I get past f/64 I have a hard time remembering the stops. It goes 90-128-180-256-360-512 right?

[Captain_joe6]

I'm sorry, I should have asked if the 28" would be f/16-180 or f/16-256 or what.

[Ernest Purdum]

Your T-R 12" is f6.8 wide open. The 21' cell works at f12.5 and the 28" at f16.

I think forgetting about stops smaller than f64 is a pretty good idea. What you can remember, though, is that each stop is twice the number of the stop two numbers behind it.

[Marv Thompson]

http://gallery.photo.net/photo/6325422-lg.jpg

This is the scale on my 12-19-25, pretty close to a 12-21-28.

As you can see the aperture range stays the same, only the largest aperture and the spacing of the stops changes.

Hope this answers some of your questions.

[Captain_joe6]

Cool, it looks like evything moves over about a third of a stop from the scale below it. That's exactly what I was looking for! Do you by chance have a larger version of that image?

[Doug Howk]

My T-R has 3 separate areas around the aperature ring, one for each lens configuration. For 12", its from f6.8 to f45; for 21", f12.5 to f64; and 28", f16 to f64.

[Captain_joe6]

For mine there is definately only one scale, and very worn at that, which goes from US-3 to US-256.

[Captain_joe6]

Just wanted to check with everyone in the TR circle, do your lenses list themselves as being "Series II" lenses, or something else? I've always seen them referred to as that, but mine says this: on one side of the front element is says "Gundlach-Manhattan Optical Co." with "Rochester, N.Y." under it. Pretty self explanatory, I know. 180-degrees from that on the front element is (in smaller, italicized letters) "Turner-Reich" and below that, larger "ANASTIGMAT." Both 12 in. and 28 in are stamped on the front with the rest of the stuff. There's nothing on the inside near the glass, because the glass goes right to the edge of the barell, except for a 1mm or so retaining edge. No "Series II" or anything like that. It does have a serial number, 76300, and a patent date, which looks like it says May 16-05. The shutter is a Wollensak Betax, made in USA, with only 1 aperture scale, not marked for focal length, and measured in the US scale. It lists a patent date of Aug. 15, 1912.

Does this all sound right?