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

Sonnar Brian

Product of the Fifties
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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.
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Bokeh Shots. They are Swirly.
Wide-Open on the Nikon Z5. In-camera Jpeg, reduced in size using ART.
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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.
 
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Shots from the neighborhood 19th century graveyard.

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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
 
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