Wide-angle: the Achilles' heel of SLRs?

[David Lyga]

Because of the inability to place the rear element closer to the film plane (the mirror gets in the way) RFs are touted as having superior wide-angle results. We know that this is so in theory and that compromises had (and still have?) to be made with optical formulas in order to 'compensate and correct'.

But, I ask, is this still so, with computer technology determining, most efficiently, the lens formulas of today? In other words, is a top flight Nikon wide angle (say 20, 24, of 28) inferior in any way to a Leica RF lens of the same focal length? - David Lyga

 

[AgX]

As you indicated hat mirror issue made it neccesary to exchange a classic wide-angle design for a retro-focus design, probably introducing additional abberations.

Nonwithstanding any achievements in retro-focus desings on which you inquire, the retro-focus principle lets the imaging rays fall onto the film with steaper angles than with the classic concept, thus the cosines-law will have less effect. Thus no need for a correcting density filter and by that a virtual speed gain of such lenses.

 

[illumiquest]

If a 4000$ Leica 21mm isn't better than a 650$ Nikon 20mm...

 

[David Lyga]

AgX: So, (in my mathematical ignorance) does that mean that the 'steeper angles' forgo the need to worry about the edges being less exposed? In terms of resolution, however, is this retro-focus compromise just as good? (Hope that I made at least some sense!) - David Lyga

 

[Mark Crabtree]

I thought this would be about the difficulty focusing wide angles on slrs. That is the Achilles' heel of slrs to me, and also the place rangefinders really shine.

For the rest, I'm in agreement with AgX that the retrofocus design can offer some advantages. Still, there are trade offs. The best modern slr wide angles are supposedly fabulous, but are generally much larger than I would want. Rangefinder lenses are usually a much smaller package.

BTW, many rangefinder lenses shorter than 35 are retrofocus too, but still shorter than slrs. Leica started doing that in the 70's, I think, to allow clearance for metering.

 

[Ian Grant]

If a 4000$ Leica 21mm isn't better than a 650$ Nikon 20mm...

It's not so much the price rather the design and there's no way of matching the quality of a pure wide angle lens with a retro focus SLR WA design.

A better example although MF not 35mm would be a comparison of the 38mm Biogon on the Hassleblad SWC with the 40mm Distagon for the regular Hasselblads.

Ian

 

[David Lyga]

Very interesting how retro-focus can actually be an advantage.

Perhaps there will be others with relevant comments on this topic. All I have ever heard is how 'compromised' the SLR wide-angles are but I see nothing but sensational results from such 'inferiority'.

Mark Crabtree: you are very correct to state that focusing them is a problem with SLRs but some are better than others. - David Lyga

 

[AgX]

AgX: So, (in my mathematical ignorance) does that mean that the 'steeper angles' forgo the need to worry about the edges being less exposed?

Yes David, that was what I meant.

At the Leica-Camera website you'll find pdf's with MTF's for both classic and retro-focus wide-angle lenses. Perhaps they'll make you wiser concerning resolution.

EDIT:
Refering to the subsequent postings, you'll also find there graphics concerning distorsion.

 

[Mark Crabtree]

Mark Crabtree: you are very correct to state that focusing them is a problem with SLRs but some are better than others. - David Lyga

That's true. I've used some pretty good finders, but they are still dependent on the lens speed. I'm happy with my 35 f2.8 Distagon, but not with focusing it indoors. With a Leica, or similar, that isn't a factor.

 

[markbarendt]

David,

As far the WA's I've used on my Nikons, all I can say is that it would be highly doubtful that simply substituting Leica gear would have "improved" anything.

I'm not saying a lab could not find something to measure, just that that difference would not have made a significant change in the success of the photos.

If a 4000$ Leica 21mm isn't better than a 650$ Nikon 20mm...

A $4000 Leica Lens is definitely better at being "jewelry".

 

[markbarendt]

That's true. I've used some pretty good finders, but they are still dependent on the lens speed. I'm happy with my 35 f2.8 Distagon, but not with focusing it indoors. With a Leica, or similar, that isn't a factor.

I agree that SLRs can provide a struggle with focus in low light, the advantage for the rangefinder here lies in the body/rangefinder mechanism not being affected by the lens brightness, right?

 

[David Lyga]

Of course, given the outrageously generous depth of field with wide-angles, you really could 'range focus' the old fashioned way and suffer nothing. - David Lyga

 

[Ian Grant]

Unless you've used a pure wide-angle lens it's hard to appreciate the differences, there's less of the exaggerated pulling effects at the edges of a similar SLR lens, it's less distorted.

I use the equivalent of a 21mm Leica lens on my 5x4 camera and in most of the images you wouldn't realise how wide angle a lens I'd used. In the early 1990's I used a 21mm on my Leica for a few months and was extremely impressed with the lens.

Ian

 

[georg16nik]

Because of the inability to place the rear element closer to the film plane (the mirror gets in the way) RFs are touted as having superior wide-angle results. We know that this is so in theory and that compromises had (and still have?) to be made with optical formulas in order to 'compensate and correct'...

David, as far as I know there are physical limits in the SLR land and so far big sized lenses with compromises is the only way to go.
What Ian Grant wrote about Biogon and Distagon in the Hassy is a good way to look at it.

In RF land, it was not until 1935 when Michail Russinov (or Roosinov) pioneered the use of aberration vignetting (to improve corner illumination) and designed vignetting filter deposited on the inner surface of the wide angle objective exterior lens..
Also, M.M Russinov pioneered the idea of enlarging the size of the entrance pupil as angular coverage increases..
By 1946 M.M.Russinov lens design (Russar) was patented and documented widely.
Zeiss and Leitz came late to the game and that explains why they used workarounds.

When Ludwig Bertele was commissioned by Zeiss in 1951 to design a wide angle lens for Contax and Hasselblad, Bertele could not obtain master patent for the use of single meniscus at each end of the lens as Russinov had already covered this.

At the International Congress at Stockholm in 1956 Ludwig Bertele paid tribute to Russinov for his highly interesting and original solution to the problem of securing adequate illumination in the picture corners etc. etc..

In 2011 Dr. Hubert Nasse, senior scientist at Zeiss and chief optical designer wrote in Camera Lens News 41 published by Zeiss Carl Zeiss AG Camera Lens Division:

"In 1946 the first patent for a new kind of symmetrical wide-angle lens was applied for by the Russian lens designer Michail Roossinov. It looked as if two retrofocus lenses had been combined with the rear elements together and thus had a symmetrical arrangement of positive refractive powers close to the aperture, surrounded at the front and back by strongly negative menisci.
As of 1951, Ludwig Bertele carried this idea further and designed the legendary Biogon on behalf of Zeiss..."

 

[MikeTime]

No complaints about the 2.8/24 and 2.8/28 Ai-S's; great '80's lenses. But then, maybe they're not real wide angles...

 

[Mark Crabtree]

Unless you've used a pure wide-angle lens it's hard to appreciate the differences, there's less of the exaggerated pulling effects at the edges of a similar SLR lens, it's less distorted.

I use the equivalent of a 21mm Leica lens on my 5x4 camera and in most of the images you wouldn't realise how wide angle a lens I'd used. In the early 1990's I used a 21mm on my Leica for a few months and was extremely impressed with the lens.

Ian

I've been wanting a 21 Super Angulon for some time. Normally I don't shoot that wide, but I really enjoy that lens. Maybe it has something to do with the characteristics you mention. With lenses, I sure like some more than others, but often can't attribute it to a particular characteristic.

The Nikkor 24 f2.8 was a very good lens for the time, and one I still like. I imagine shooting it side by side with a Super Angulon would show up some significant differences.

And, of course, that doesn't mean your pictures would be better with a better lens, but that wasn't the question here.

 

[Diapositivo]

I am not a lens design expert but would agree with the theory that wherever there is some additional constraints in lens design, either price or lens quality has to suffer, or both.

I have a small and quite well made Voigtländer 15mm on my Voigtländer Bessa-L and the pair is light, portable, and fairly inexpensive.
A 15mm on a SLR would undoubtedly be more expensive, heavier, and very likely sacrifice some image quality on the altar of design complexity. I very often take pictures of architectural subjects so distortion correction is something I deeply like.

I would say that, overall, wide-angle photography is something that would better be left at range-finders. If you are the kind of persons that goes around with two or three bodies, the wide-angle body should be a range-finder (or quasi range-finder, like a Contax G2). It's not just a matter of distortion correction but also a matter of weight and size.

 

[Bill Burk]

Enjoyed the lens design story, thanks georg16nik.

As several have noted... In terms of ease of focus and composition... rangefinders are well suited to wide angle, while SLR's are better suited to telephoto.

 

[semi-ambivalent]

Michael,

In the late 70s a "teacher" at the traveling Nikon School said wide angles don't have distortion but exaggerated perspective. He followed with a sensible proof using the ratio of distance to foreground objects and distance to background objects. Whether or not this was provided to explain away true distortion in WA Nikkors versus WAs by Leitz I don't know but 1) It made perfect sense, and 2) I've never had much problem with "distortion" if I framed the image correctly. Usually, I was after the FG/BG thing so I coaxed it as much as I could. And, with the Nikkor Retros I could actually afford the 28s, 24s and 20s that let me get the images I was after. If Leitz was the only source of wide angles I doubt I would have ever picked up a camera. I have no doubt the geometries and optics can affect things here but must also think at least some of the spiel behind $3k 35s is to explain away Leica's antiquated production workflow.

 

[AgX]

The terminology on these matters is vague.

I would distinguish between:

-) perspective distortion

-) geometric distortion

-) lens distortion

I admit that these terms too are ambiguous.

 

[semi-ambivalent]

Enjoyed the lens design story, thanks georg16nik.

As several have noted... In terms of ease of focus and composition... rangefinders are well suited to wide angle, while SLR's are better suited to telephoto.

Bill,

I've never had a problem focusing a (Nikon) WA. One must only pull the split prism to the point you want focused and turn the camera a bit, if necessary, to get some angle across the split. Focus, compose and done. This works for me down to f/3.5, the slowest WA I have (28mm non-Ai). I'm 58 so we'll see what my eyes have to say about this going forward. Additionally an RF, unless I use an external viewfinder, does not show me the 'distortion' a WA provides, only its FOV, an SLR cannot avoid showing both. I am often after just that and it helps composition to be able to see it.

Having the muscle memory to pull that split prism around, now that I own an M3 one would think it would be easy to remember that I have to pull that split image around too. But I'm having a hell of a time remembering that when things are moving fast (My kingdom for a ground glass!). This might help explain the popularity of 35mm lenses for RFs; the DOF makes it easier to go all HCB on it.

s-a

 

[Diapositivo]

Michael,

In the late 70s a "teacher" at the traveling Nikon School said wide angles don't have distortion but exaggerated perspective. He followed with a sensible proof using the ratio of distance to foreground objects and distance to background objects. Whether or not this was provided to explain away true distortion in WA Nikkors versus WAs by Leitz I don't know but 1) It made perfect sense, and 2) I've never had much problem with "distortion" if I framed the image correctly.

"Distortion" is a lens defect. Some people use the term "geometric distortion" to express the typical wide-angle perspective. Some other people call that wide-angle perspective "distortion" but that really is incorrect IMO. The teacher was probably explaining them that that is not "distortion" but has a geometrical - optical explanation and is, therefore, unavoidable and perfectly normal.

That said, wide angles have distortion proper just like any other lenses.

 

[Bill Burk]

semi-ambivalent,

I guess I too never have any real "problem" focusing wide angle with an SLR. And I also have no trouble focusing a 90mm with M2... It's just that it seems relatively easier (since focus patch is the same for any lens) to focus the rangefinder with wide angle...

 

[semi-ambivalent]

semi-ambivalent,

I guess I too never have any real "problem" focusing wide angle with an SLR. And I also have no trouble focusing a 90mm with M2... It's just that it seems relatively easier (since focus patch is the same for any lens) to focus the rangefinder with wide angle...

Bill,

Not trying to pick a quarrel here. I'm certainly having problems teaching my brain RF-mode, but none of the 'problems' I'm having relate to the supposed benefits/weaknesses of RF/SLR that are at the nucleus of most of the gentlemanly bickering that goes on about such subjects. It sometimes sounds like both camps have circled the wagons, and stalemate ensued.

s-a

 

[Bill Burk]

Bill,

Not trying to pick a quarrel here.

Thought never occurred to me...

I guess it's more a "strengths" issue, not really a problem. Take 50mm as neutral. Both RF and SLR work well at normal. Then put a wide angle on an SLR and everything kind of always seems in focus (because of the greater depth of field). So this could cause a focus error. While a rangefinder will encourage you to focus just as accurately.

Then put a slight telephoto on an SLR and start taking portrait photos. It's just pure fun. While the rangefinder with a telephoto just seems like a kludge. The M2 did a good workaround by moving the framelines. But my Contax didn't - requires accessory finder or guesswork.