Pre-war Biotar 5cm F2, uncoated with Domed Aperture.

Sonnar Brian

Product of the Fifties
Staff member
Local time
4:51 PM
Joined
Jan 12, 2004
Messages
19,839
I picked this lens up recently, to go with the post-war Biotar "T" 5.8cm F2 early version. This version is different. It features a Dome aperture, the blades follow the curvature of the front doublet as it closes down. I've never seen another lens that has this feature, the post-war lens does not. I can speculate that it was done to reduce reflections off the aperture blades, to point them outward and out of the optical path. Maybe some optical trick to mitigate effects of spherical aberration- I do not know. The bayonet mount is machined a bit differently than the post-war lens. Both fit my Exakta Varex - but the older lens would not fit my Exakta to M-Mount adapter. I ordered an inexpensive Fotasy Exa to Z-mount adapter, the lens fits easily and focus is perfect at infinity. This lens is from the first production batch of 300 5.8cm F2 Biotars. Following batches may have changed formula and mechanical specs- this is the only pre-war Biotar 5.8cm F2 that I have handled. I had a 4cm F1.4 Biotar, gave it to Chris at Skyllaney.

With my favorite Coffee Cup. Bought back when I was a Rocket Scientist. and yes, we took breaks for Ice Cream from the soft-serve machine at the cafeteria.
And Ice Cream Trucks.
RIMG0328.jpgRIMG0329.jpg


DSC_3518.jpgDSC_3529.jpg
 
Last edited:
Bokeh Shots. They are Swirly.
Wide-Open on the Nikon Z5. In-camera Jpeg, reduced in size using ART.
DSC_3581.jpgDSC_3583.jpgDSC_3585.jpg


This lens is much sharper than I thought it would be. It is lower contrast, but the Z5 JPEG engine seems to normalize for that.
 
Last edited:
Shots from the neighborhood 19th century graveyard.

DSC_3551.jpgDSC_3555.jpgDSC_3556.jpgDSC_3562.jpgDSC_3566.jpgDSC_3572.jpg

No wonder people bought Exakta cameras in the 1930s.
These days- this one, and the post-war lens are easy to use on Mirrorless cameras. Focus on this lens was very smooth, my post-war lens was very stiff. I partially disassembled and relubed the post-war lens, and a wartime Tessar 5cm F2.8 in Exakta mount after receiving the uncoated lens.
 
I somehow found a T 50mm 1:2 biotar sitting around my office. IT's a M42 mount. Never used myself ...preset aperture not my preference.

I never did anything with it which is sad. I have an URTH adapter to F....it seems with a glass element as I was hoping to use the only other M42 around as Super Multi Coasted Takumar 50 1.4. Unfortunately, the Pentax lens could not be seated in the the adapter. I showed URTH that this particular lens has a bulging rear element that others don't and it also had pin for open aperture metering. they finally gave up.

This one is not in the hands of the right owner. Maybe I'll try the Biotar with an appropriate F cam.
 
If you are shooting film- easiest to buy an M42 camera, they are cheap. Better than requiring the correction optics in the adapter.
The Argus/Cosina STL 1000 is basically a Nikkormat with an M42 mount. Usually $25 or so.
 
thanks BRian. However, was hoping to find a decent spotmatic F with a working meter so I could mount the Takumar and make use of the open aperture feature. Still could a cheap M4 2 mount cam.
Hap
 
I picked this lens up recently, to go with the post-war Biotar "T" 5.8cm F2 early version. This version is different. It features a Dome aperture, the blades follow the curvature of the front doublet as it closes down. I've never seen another lens that has this feature, the post-war lens does not. I can speculate that it was done to reduce reflections off the aperture blades, to point them outward and out of the optical path. Maybe some optical trick to mitigate effects of spherical aberration- I do not know. The bayonet mount is machined a bit differently than the post-war lens. Both fit my Exakta Varex - but the older lens would not fit my Exakta to M-Mount adapter. I ordered an inexpensive Fotasy Exa to Z-mount adapter, the lens fits easily and focus is perfect at infinity. This lens is from the first production batch of 300 5.8cm F2 Biotars. Following batches may have changed formula and mechanical specs- this is the only pre-war Biotar 5.8cm F2 that I have handled. I had a 4cm F1.4 Biotar, gave it to Chris at Skyllaney.

With my favorite Coffee Cup. Bought back when I was a Rocket Scientist. and yes, we took breaks for Ice Cream from the soft-serve machine at the cafeteria.
And Ice Cream Trucks.
View attachment 4830932View attachment 4830933


View attachment 4830935View attachment 4830936
Beautiful and historical lens. I'd like to ask how you know it belongs to the batch of the first 300 made. I haven't found any record of those serial numbers and would like that information. Thank you.
 
It is interesting that you can suss out a lens with two shots: F2 and F4. Folks can do that if they know what they are doing. Back in the Dark Ages it was necessary to read a short Mark Twain story to OS/2 and let it run for 12 - 14 hours to learn to recognize your speech. Now I think that the Google software can recognize your speech if you say "Google" or some other simple word.

And a further tangent, a fellow I knew as a freshman had done a summer internship at Princeton under some mad scientist. This was in the late 50's and the mad scientist was developing a voice recognition system on what were computers then. And it worked perfectly, if you had a thick Hungarian accent. We have come a long way.

I bet that they, too, all ran when the ice cream truck came by. People are people regardless of how long they have been in class. And a Good Humor Raspberry Ice Stik is always irresistible. That's a law of physics.
 
I have a 4 1/4cm f 2Biotar in Contax mount that appears to have a domed aperture. Not a dramatic rounding, but looks different than a standard flat iris when stopped down all the way. Not as early as your lens, mine is 2217230. Hard to get a pic of the aperture, and I am reluctant to pull the glass to confirm.

 
Last edited:
Beautiful and historical lens. I'd like to ask how you know it belongs to the batch of the first 300 made. I haven't found any record of those serial numbers and would like that information. Thank you.
Information is found in Hartmut Thiele's "Fabrikationsbuch Photooptik II, Carl Zeiss Jena". I know that Sonnar B has a copy of the book. I looked it up in my copy and agree with Brian
 
I don't have Thiele's book yet, but here's the 10 earliest 5.8cm f2 Biotars that I've personally observed:

View attachment 4873171
Thiele's book of CZJ lenses says that earliest 5.8cm f2 Biotar is 1,903,693, a single copy produced in SF mount, whatever that is, completed November 25, 1936. The next earliest series is 2,009,101 to 2, 009,400 dating to December 14, 1936, in Exacta mount. I am not suggesting that Thiele's book is infallible, but it is the best source of info on CZJ production. Also, this is probably the first time in my life that I have ever typed the word infallible. Serial number 2093325 would place this lens in the third batch of 300 Biotars in Exacta mount, production date of June 1, 1937 according to Thiele (ATT). I may adopt the abbreviation ATT in future posts 😉
 
Last edited:
I have a 4 1/4cm f 2Biotar in Contax mount that appears to have a domed aperture. Not a dramatic rounding, but looks different than a standard flat iris when stopped down all the way. Not as early as your lens, mine is 2217230. Hard to get a pic of the aperture, and I am reluctant to pull the glass to confirm.
My LTM Biotar which is a 1.4million serial has the domed aperture. I know because I serviced it and the condition was so bad I had to take the blades out. It was a nightmare to get back. The blades as I painfully learned are not only curved but the curvature is bespoke to the position they're in. A lot of bad words were said, but I got it back together..

Thiele's book of CZJ lenses says that earliest 5.8cm f2 Biotar is 1,903,693, a single copy produced in SF mount, whatever that is, completed November 25, 1936. The next earliest series is 2,009,101 to 2, 009,400 dating to December 14, 1936, in Exacta mount. I am not suggesting that Thiele's book is infallible, but it is the best source of info on CZJ production. Also, this is probably the first time in my life that I have ever typed the word infallible. Serial number 2093325 would place this lens in the third batch of 300 Biotars in Exacta mount, production date of June 1, 1937 according to Thiele (ATT). I may adopt the abbreviation ATT in future posts 😉
SF stands for "Sonderfassung" which could translate to either special manufacture or special mount. It might very well have been a prototype.
 
Back
Top Bottom