Dallmeyer Stigmatic question

[Shen45]

I have a 10.7" Stigmatic with a near pristene front element and a very badly scratched rear element. I seem to recall that the front element can be used on its own but I'm not certain on the focal length it becomes or the change in aperture.

The present f stop range is from f6 to 45

I think the lens focal length either doubles or is x1.6 but I'm not certain which or if either of those factors is correct.

I don't have the lens on a board as yet to roughly measure the focal length.

Does anyone have one of these and any comments?

Steve

[Ernest Purdum]

I've never used a Stigmatic lens, but I've got an old catalog which gives the front cell as twice the length of the complete lens and the rear cell as 1 1/2 times the whole works.

Your 10.7 lens is rated to cover whole plate wide open and 12" X 15" at f16. The coverage of the individual cells isn't mentioned, but is unlikely to be much more.

As a convertible, the Stigmatic is quite unusual in being distinctly asymmetrical.

Since there is no aperture magnification when using only one cell, you can figure the f number just by dividing the focal length (21.4" for your front cell) by the actual diameter of the glass.

[Shen45]

I've never used a Stigmatic lens, but I've got an old catalog which gives the front cell as twice the length of the complete lens and the rear cell as 1 1/2 times the whole works.

Your 10.7 lens is rated to cover whole plate wide open and 12" X 15" at f16. The coverage of the individual cells isn't mentioned, but is unlikely to be much more.

As a convertible, the Stigmatic is quite unusual in being distinctly asymmetrical.

Since there is no aperture magnification when using only one cell, you can figure the f number just by dividing the focal length (21.4" for your front cell) by the actual diameter of the glass.

Thanks Ernest,

That is just the information I need. I will mount the lens on a board and see how it performs tomorrow.

Steve

[Maris Rusis]

I have a No.6 SER II Dallmeyer Stigmatic F/6 Patent F=10.7"=27cm lens. It used to cover 8x10 nicely.

The front group alone is marked F=25"=63cm. The rear group is marked F=16"=40cm. Both groups cover 8x10 with soft-ish central definition and the corners a bit fuzzier.

The aperture on my 10.7" Stigmatic is calibrated from f=6 to f=64.

The front two elements of the Stigmatic can be separated for cleaning but the rear two glasses are locked together in a spun brass cell. I cut this cell to release the cemented doublet which forms the rear group. During de-cementing with solvent both glasses spontaneously shattered internally but held shape to maintain their external form. The pair now form an outrageous soft focus lens.

[Lynn Jones]

As long as the scratch is not in the exact certer of the lens, if will have no affect whatsoever.

Lynn