jena 50mm f2.8 brightness comparison

[ddashk]

i have had a zebra 50 2.8 for years and the other day i acquired an "aus jena ddr" copy.

firstly if any one has info re years etc for the lens i would be very interested.

secondly i noticed something strange about the lenses.

i took some test shots and realised that the aus jena ddr version seemed to be brighter.

i set up a shot and sed the camera to av. i changed the lenses and nothing else in between.

even though the framing etc is remarkably similar the zebra lens gave a exposure of 1/160 and the other lens gave 1/200.

as you can see the images are identically exposed.
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[Pancolart]

[Ymmot]

Actually as far as I know, the T on the lens is not for the coating, just to denote that it is a Tessar.
If I remember correctly the 135mm jena Sonnar which are denoted on the name ring with aus Jena DDR have an additional S marking for Sonnar.
May have been to do with trademarks from western Zeiss and exports to western world instead of Sovjet Union.
Multicoated Zeiss Jena lenses are just denoted with a (usually red) MC marking.


I suppose different glass/ coating variation/ construction differences/ possible haze even? may affect exposure?
Has one of the lenses yellowed, as also the color seems yellower/warmer on the 1/160 shot, which may also affect light transmission a bit?

Just a random thought, do you have Auto ISO on? I don't know how your Av mode works, though in aperture priority mode, my camera (Olympus) still allows for automatic ISO, so did you set the ISO manually?

[iangreenhalgh1]

Yes, T means Tessar, multicoated DDR lenses have MC on them.

Due to legal battles, you will find lenses mared 'aus Jena' Instead of Carl Zeiss and with a T or a S for Tessar or Sonnar.

aus Jena T = Carl Zeiss Tessar

Different labels for different markets, same lens.

[ddashk]

i used manual mode with iso 100.

both lenses are in good condition and have no fungus/dodgy coatings etc.

neither lens is noticeably yellowed.

although the exposure difference is small i can think of times when 1/200 would give a different shot to 1/160. for example skateboarding or sports in the evening when iso is at the limit.

[tromboads]

I had that deodorant, Didn't like it tho.

[ForenSeil]

I guess the non-zebra has better/more advanced coatings.

Coating and glas sorts can influence transmission a lot, even with an identical optical design.

[nukemall]

Converting "ausJena T" to "Carl Zeiss Jena Tessar"



Just unscrew nameplate ring.

[iangreenhalgh1]

I've seen other examples of that - adding a new name ring - last one I saw was a 4/135 silver Sonnar that became aus Jena S.

[IAZA]

I tried zebra tessar, CZ Tessar MC, and black jena T.
Zebra one is worst.

[calvin83]

[IAZA]

I checked again.. Sorry my mistake, No MC. jus CZJ DDR Tessar

[enliten]

Do the zebra tessars have any coating on them at all?

If so, what are the chances it was on the front or rear elements and has long since been cleaned off.

[Ymmot]

Have you tried a (blueish LED) flashlight test on the lenses.
You would be surprised in terms of crap / haze an apparently clean to the eye lens has inside .
I have an apparently clean to the eye under normal lighting minolta 100mm macro that more or less turns milky when shining a flashlight through it (it is a bit fungussy, so not too unexpected in this case).
(seriously, for peace of mind, don't do it, it makes you worry needlessly about lenses with no particular issues )