BJP's Leica/Zeiss rangefinder lens comparisons

[dkpeterborough]

In BJP magazine 3 January, Anders Uschold compares the Leica and Zeiss 21mm f2.8, 28mm f2.8 and 50mm f2 rangefinder lenses when used on the M8 ... and also compares corner shading (vignetting) with and without encoding.

The Zeiss lenses tested gave excellent performances and when compared with Leica there appears not to be much difference in the quality of imagery ... swings and roundabouts. Vignetting appears to be about the same with both brands for the wide angle lenses and, "is an issue" without any compensation ... but when the Leica lenses encoded compensation was used vignetting was less. With the 50mm lenses vignetting seems to have been less of an issue ... and the author suggests that upgrading of the 50/2 Summicron is not too necessary.

The article covers 4 pages and is technically very interesting ref the design constraints of retrofocus slr lenses compared with the simpler symmetrical rangefinder type lenses.

Not covered in the article (unless I missed it) are differences in build quality and price ... but the author does state "both lenses are well crafted"

The article can be read on the BJP website British Journal of Photography if you take out a free trial subscription ... the actual magazine should have been on the shelves yesterday but was not avilable in my newsagent presumably because of New Year holidays.

Dunk

[DTD]

Originally Posted by dkpeterborough

technically very interesting ref the design constraints of retrofocus slr lenses compared with the simpler symmetrical rangefinder type lenses.
Dunk

I found that bit particulary interesting as well.

[jonoslack]

Hi Dunk
An excellent article I thought. Like both of you, I was interested in the stuff about symmetrical design, and now I understand why the CV 15 can be tiny whereas 15mm lenses for dSLR cameras are huge (especially full frame).

[carstenw]

Well, it is only f/4.5 which is pretty rare. Look at the Zeiss 15mm f/2.8 to compare with SLRs.

[sdai]

Both the 21/2.8 ZM and the 21/4.5 ZM are Distagons, retro-focalized ... unlike the classic Biogons, and are not rangefinder coupled ...

[carstenw]

Retro-focalized? Retro-focus? In that case we need other lenses to compare with

[jonoslack]

Originally Posted by carstenw

Well, it is only f/4.5 which is pretty rare. Look at the Zeiss 15mm f/2.8 to compare with SLRs.

Hmm - is that a symmetrical design? (honest question, I don't know the answer).
But the principle is that symmetrical lenses can be much smaller, and it does seem to be borne out by Leica lens sizes, wouldn't you agree?

[sdai]

Sorry ... I meant to say the Distagon 4/18 ZM, not the Biogon 4.5/21 ZM.

[carstenw]

Yes, definitely. Apparently each focal length has its own natural center of symmetry, so a camera with a fixed flange-sensor distance, ie. all of them, can only ever be a compromise except for one single focal length. A large distance, like most SLRs, is a pretty hard constraint though, AFAIK. A rangefinder is much easier on lens design, since the distance is so small, but there is still a compromise there.

[pelikan1931]

Originally Posted by sdai

Sorry ... I meant to say the Distagon 4/18 ZM, not the Biogon 4.5/21 ZM.

how do you know that, Zeiss has not released any public information on the coming distagon 18/4 zm...

[sdai]

Distagon lenses are wide-angle retrofocus lenses.

[Marijn]

Actually, I don't think any current production wide angles for 35mm are true symmetrical designs. As far as I can see, all of the Zeiss, Voigtlander and Leica wide angles currently in production are at least slight retrofocus designs (even the Biogons and the Voigtlander 15mm), usually in order to clear the meter inside the camera or to enable a larger aperture.

Of course all SLR wides are retrofocus, so that might leave a few non-interchangeable lenses on 35mm compact cameras, but I don't think many of those are in current production either.

Feel free to prove me wrong, naturally.

[jaapv]

Hard to prove you wrong, as most new (at least the more expensive ones) rangefinder wideangle lenses are of retrofocus design, as this gives the designer more scope to correct optical errors. The limits of the symmetrical design have been reached decades ago and the computing power of nowadays, plus the ability to produce to smaller tolerances has made this advance possible.

[marknorton]

I'm still surprised when I mount the 35mm/1.4 or the 28mm/2 to see those concave front elements. Who would have thought for a wide-angle lens?

[jaapv]

The Summicron 35 asph too....