Help in identifying early large brass Carl Zeiss Jena lens

[rossn4]

Hi, I recently picked up this zeiss lens and other then the name and patent on it I am wondering if anyone knows what type of lens it is. It is a large barrel lens approx. 4" by 4". It says "Carl Zeiss Jena D.R.P. 84996". It has a iris diaphragm and a waterhouse slot. The scale given is 3 4 6 8 12 17 24 34 48 with several ticks beyond that. I put it on my 12x16" camera and it covered the whole ground glass wide open and had an approx. focal length at infinity at 18". I looked at the Vademecum book and was only able to figure out that its an early lens from around 1890. I am including some pictures I took of it. Thanks.

[Louis Pacilla]

My guess given I don't have the lens in my and I'm assuming that the stops are US and not "f" stops US- 3 is F-8 and without counting reflections my guess is a Protar Series II f8 Size 8 433mm or 17" that covers probably around 65 degrees stopped down. They give 75degrees as the coverage but usually with the larger sizes (#6-8) the coverage drops a bit with the unequal or non symmetrical Protars. They do not mention it in this catalog and they usually do if this is the case so who knows.

Ziess gives IC at small stop as 26 3/8" w/ the Protar Series II #8 17"f8 so it should cover at least a 16x20 with some room for movements stopped down and maybe cover 20x24 w/ no room to little room for movements.

Aagin, my "best" guess. Should be close.

[Jim Galli]

On the scale, is 3 the smallest hole, or the largest? Sometimes Zeiss just gave you a mm scale and let you do the math.

[MDR]

The patent number is for the Iris diaphragm and not the lens. Zeiss also used their own Diaphragm numbers which are not identical to the US-Stops to further muddy the water Zeiss used several different numeral systems. But looking at the pictures I would guess that Jim Galli is right and that it's marked in mm. I assume the last number would be 60 so it would open to around f7 to 7.7 just like a classic double protar or Zeiss Anastigmat

Aside from a Protar it could also be a Unar or a simple pre-protar Anastigmat. The Double-Protar has more lens elements (count the reflections) then the Unar (4 Elements) a single Protar is a 4 Element lens like the Unar of those two the Unar is probably the better lens. Since it has both a waterhouse stop as well as an iris diaphragm it could also be a repro lens.

[Louis Pacilla]

I thought Zeiss went the other way? So f8 would like 176 in the Zeiss diaphragm stop #


I thought OP had two sets of diaphragm scales one for the cells that are present & not the metric iris division scale which seems to be present on all Zeiss barrels of this age and size.

I have a Series IIIa 505mm f9 which the barrel has both f stops and one the other side the Metric iris division scale.

[rossn4]

Thank you for the responses. Here is what the two elements look like when removed from the barrel. The front section is certainly two elements as there is some cement separation between them. I see two reflections when looking through the rear so that is probably two as well.
110428

[Steven Tribe]

Well this is what it is - very obscure!


"The next non-anastigmat is probably a more prosaic item and is likely to be later. It was possible to see a
"Aplanat fur Projection" f6.7 200mm. This was a Zeiss lens in a brass mount with an iris calibrated in mm
(28-3mm). It must be a rare lens and non-anastigmatic but may not be photographic. It was seen at Nr 1,02x,
DRP 84,996. The Patent No seems later than expected and the lens may be a 1892-5 period item. But it is
unusual as a non-anastigmat Zeiss lens and it is certainly not a normal photographic lens as the correction is
really sharp in the centre but only over a 10-15cm radius, and then falls off markedly. This would be a
reasonable performance for a projection lens but not really acceptable for normal camera work. It also raises
questions over the serial numbering sequence then in use- perhaps the projection lens was numbered in a
different series with a later start date."