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View Full Version : Aperture scale on Isconar 180



Jimi
20-Sep-2019, 02:01
I am starting out to actually use an half-old (1930's from what I can gather) "Jos. Schneider Co. & Kreuznach Doppelanastigmat Isconar" lens, and the aperture scale progression always throws me a bit: f:6.8, then 9, 12,5, 18, 25, 36 and the 50 as the smallest stop.

Would that (sort of, leaving out the first 6.8), correspond to f:9 being f:11, and then 16, 22, 32, 45, and on to f:64?

It seems like a nice lens, but I need to dial in the process a bit, since I am using it with a lens cap - rather low contrast negatives even with a rotary process.

Dan Fromm
20-Sep-2019, 04:54
No, the aperture scale is what it is. The list has a link to a spreadsheet that will make things clearer. Look at the column headed Congres 1900.

Which meter do you use?

Jimi
20-Sep-2019, 05:17
Thanks, Dan - forgot to look in the list - of course! :)

I am using a Sekonic L308s and in the future do FP4+, rated at EI 50, but I guess since I am using a lens cap (unless I find a LUC shutter or similar that is small enough) the exposures anyways will tend towards overexposure.

As an aside, I had a look at my LUC shutter (a no. 4) and now I see that I might be able to kludge some rubberband or something onto the lens to make it fit (a few millimetres missing).

Dan Fromm
20-Sep-2019, 05:59
I've never looked at an L-308 or an L-308 user manual, but I have one for my humble L-328. The L-328 reads in half stop increments, which will get you close enough, especially since you can interpolate between marked stops when setting the aperture.

Oren Grad
20-Sep-2019, 06:36
Dan, the L308 series meters read out in tenth-stop increments.

Dan Fromm
20-Sep-2019, 07:07
Thanks, Oren. So the OP can see exactly what he needs.