Red dot on Zeiss Jena 13.5 cm

[nathanielpaust]

I just got a new (very old) lens, and I have a question about it that I'm hoping the group here can answer.

 

Between f11 and f16, there's a red dot on the aperture scale. It's not just a random drip of paint, it looks like it's there on purpose since there's a little engraved hole that's filled with the red paint.

 

Does anyone know what this dot could signify?<div></div>

[c_p_goerz]

Possibly the optimum aperture setting but more likely an F stop setting for a Hyperfocal distance setting.

 

 

CP Goerz

[arne_croell]

This lens probably came from a 9x12 or similar size folder camera; I second that its a hyperfocal setting or something similar (optimum setting for a group portrait?). The circle of confusion used to determine that setting was probably pretty large, maybe just for contact printing.

[allen_whittier]

I agree with hyperfocal. Old folders frequently had this dot. I must add a thing or two about this lens. It makes a great 4x5 slightly wider than normal lens. Very sharp when stopped down to f11 or smaller. I actually used it on my 5x7 when I got in a pinch one day. Needed a little more coverage than my 146mm Protar, pulled it off the 4x5 board and put it on my 5x7. I closed it to f32 and covered corner to corner. What a pleasantly surprised. When the film was developed I

had fine focus and little drop-off. This was B&W with a red filter. Haven't tried color yet.

[ole_tjugen]

I could understand the optimum settings, or the hyperfocal setting, if this were a front-cell focusing lens. The ones I have of that kind are full of little marks and rings, but I can't imagine what a dot on the aperture scale could have to do with hyperfocal setting. It might be the setting for optimum sharpness, but I'm still not convinced...

[arne_croell]

Ole, I would assume (but that is speculation) that there was a corresponding mark on the rail bed for positioning the lens standard, or maybe a click stop. Then the hyperfocal theory would work.

[ole_tjugen]

Yes, Arne - but who would want the hyperfocal distance at f:13.5 (which looks like where it is)?

 

Maube it's a code for "aperture scale for a 135mm lens"? If we could find a 150mm with the red dot closer to f:16, or even a 210mm with a dot next to f:22...

[ken_schroeder]

Allen may have hit upon a point when he stated it is very sharp when stopped down to f 11 or more. The 135mm lens is really the normal lens for 3 1/4x4 1/4. Some of the old books talked about the 135 being a little unsharp around the corners when used with 4x5 unless stopped down. It's a guess, but maybe the red dot indicates the point where coverage was considered acceptable for 4x5.

 

I'm no Zeiss expert. Zeiss had factories in both the former Eastern and Western areas. Jena was in the east. Perhaps someone would know if the "Jena" designation was postwar, or just an indicator of the plant of manufacture.

[arne_croell]

This is a prewar lens; from the serial no it was made around 1937-1938.