5.8cm F2 Biotar "T", 17-Blade version.

[Sonnar Brian]

I took this lens to the skating rink a couple of weeks ago- came to the conclusion it was unusable without a clean and relube. Stiff, very stiff, hands hurt turning the focus ring- time to relube.

Not a hard job, also took the time to remove the optics and clean the surfaces.
I found a youtube video for the process. I prefer written documentation, but this video helped a lot.



This could become a favorite lens on the Z5.



40.5mm filters and accesories, same as the 5cm F1.5 Sonnar. I put a Walz vented hood on it.

Wide-Open on the Z5.



This lens is small, like an RF lens- lack of automatic aperture. On a mirrorless camera, makes no difference: adapter manual focus lenses lose the auto-aperture. In dim lighting- I shoot wide-open. The Mirrorless cameras have enough latitude to make focus easy stopped down even to F8 or so.

These are all wide-open.

 

[dexdog]

i have one of those in m42. i like it stopped down a bit, but find the swirly OOF areas to be too distracting wide open. interesting that the swirlies don't show up as well in lower light.

 

[Sonnar Brian]

Swirlies show up when the lens is at a close focus, like for a portrait. For a medium distance shot- does not have the same effect.

 

[santino]

I just don’t get what actually causes the swirlies. In my impression my most swirly lens is the Helios 77-M4 which is not a Biotar copy 🤔

 

[Sonnar Brian]

I looked up Helios-77. It is a 6 element in 4 group, 1-2-2-1, Double Gauss, same configuration as the Biotar.

The Swirlies - caused by residual astigmatism in the lens. Introducing some field curvature would reduce it, so a trade-off.

 

[santino]

Ah ok, I think I mixed up something. I‘ve heard that the Helios 77-M4 is a copy of the Oreston, but it seems like the Oreston itself is a Biotar type lens. That explains it.

 

[hap]

Hi I have a biotar which looks like on the right side of your picture. Not sure I can count the # aperture blades. I think it is 12. However, just asking since mine is similar to your lens on the right.

thanks

 

[Räuber]

There is a very nice review of the Biotar 5,8cm f/2 here. It has an overview over the different versions of this lens too that I found very helpful.

I myself own a 17blade black one in Exakta mount just like this one. I think it kind of looks cool. 😎 I found it quite difficult to get the swirl to show up. It is not like you see this effect in every image though. Maybe I have to experiment way more with this lens to find out how to provoke this look.

 

[Sonnar Brian]

Hi I have a biotar which looks like on the right side of your picture. Not sure I can count the # aperture blades. I think it is 12. However, just asking since mine is similar to your lens on the right.

thanks

Sorry I'm late.... getting over some nasty cold.

Can you post a picture? I suspect you have a later pre-set version, which looks more like my J-9 on the right of the shot.

For Cheyenne Morrison's article: The filter size for my First-Batch, pre-war 5.8cm F2 Biotar is 40mm- NOT 40.5mm.
I have a Series-VI adapter and hood made for a Canon 50/1.8 on it right now.

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

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...

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