Thoughts on the Zeiss 50mm f/2

[ediz7531]

Hi all,

What do people think about the coated Zeiss 50mm f/2 for the contax iia and iiia series? One hears praises for the f/1.5 version, so I thought I’d inquire from those of you who own the f/2.

 

[Cascadilla]

I own both--they are both excellent. It would be hard to choose between them, but if you need f/1.5 for low light then the choice is obvious. Likewise, if you need f/22 for depth of field, then you need the f/2, since the f/1.5 only stops down to f/16.

 

[Bingley]

I also have both the Sonnar 50mm f.2.0 and the Sonnar 50mm f1.5 (both are Zeiss Opton versions from the 1950s). I concur with Cascadilla’s assessment. The f2.0 is excellent. It’s overshadowed by the f1.5, but is a beautiful optic. If you can find a clean one at a good price, I’d jump on it. You can also get adapters that will allow you to use this lens (and the f1.5 too) on Leica M mount and LTM cameras.

 

[ediz7531]

Thank you both.

 

[D.O'K.]

I have both and also agree with Cascadilla and Bingley. Great lenses, particularly with b+w.

That said, I recall reading (sorry I can't remember where, but it was someone I found credible) that diffraction becomes noticeable much sooner with the 1.5-well before f11, as a consequence of the design priority being superior low light/wide aperture performance. I've not noticed this myself, but tend not to print 35mm larger than 7x5".

Regards,
D.

 

[Cascadilla]

I have both and also agree with Cascadilla and Bingley. Great lenses, particularly with b+w.

That said, I recall reading (sorry I can't remember where, but it was someone I found credible) that diffraction becomes noticeable much sooner with the 1.5-well before f11, as a consequence of the design priority being superior low light/wide aperture performance. I've not noticed this myself, but tend not to print 35mm larger than 7x5".

Regards,
D.

I also have a pre-war f/1.5 Sonnar that only stops down to f/11, and according to Kuc's On the Trail of the Contax it was because of the fear of diffraction degrading the image quality. An interesting question is why the 28 mm f/8 Tessar for the Contax has f/32 for its minimum aperture--you would think that diffraction would be severe at that small an f/stop for such a short focal length.

 

[D.O'K.]

Indeed it's surprising. Possibly the Tessar formula was somehow less prone to diffraction than the Sonnar's? But I've no idea (wish I knew more about optical science).

I handled a 28mm only once--a tiny lens, and I do remember the aperture was absolutely miniscule when stopped down. Don't know what it's performance was like, but I'd have modest expectations at f32...

Regards,
D.

 

[brusby]

I believe diffraction is primarily a function of the size of the aperture in relation to the focal length of the lens. As the lens opening gets smaller, the proportion of light rays going past the blades and bending as a result, versus the light going through the lens that is unaffected by this phenomenon, is increased.

So, all 28mm lenses at f11, regardless of who the manufacturer is, would have roughly the same amount of diffraction.

But I'm not an optical engineer and I'd be happy to be corrected if my understanding is not right.