This weekend with a 35/2.8 C-Biogon & 35 Sumicron v. IV

Sorry for not being clear. When I owned both these lenses at the same time awhile ago, I felt that the Summicron displayed a more predictable dof at wide apertures (less field curvature and more depth). I never tried to demonstrate or test this observation because I sold the Summicron for other reasons. I was reminded of this when I noticed in Ben's pics that the subject in the Zeiss shot had only one eye in sharp focus, while the subject in the Cron shot had both eyes in focus: "deeper" dof in the Cron picture.

I dug out the only files I have that illustrate my point about the differing configuration of the two lenses' dof. While the two pics weren't taken at the same time, in the same light, etc., they have the same subject and were taken from the same camera position at f2, however. I believe the fact that the tree is in clearer focus in the Cron pic compare to the Zeiss pic suggests that the dof of the Cron is wider, or less curved, or at least more beneficial from the standpoint of predictability and getting more of the subject in focus (in Ben's pics, two eyes rather than one).

If this is not making sense or is just obscure, I'm happy to delete my post. Don't want to detract from the thread.
 
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MCTuomey said:
If this is not making sense or is just obscure, I'm happy to delete my post. Don't want to detract from the thread.
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No no, your statement is clear now, and the thread *is* about Biogon vs. Cron v.4, after all.

It's the fact that the pictures are so different that has me stumped. In theory, two lenses of the same focal length should have the same DOF at the same aperture. And if it's curvature of field, we should see the wall go out of focus in the Biogon shot edges... 😕
 
I will try to post some more definitive pix this weekend under more controlled conditions. There are many variables in lens design, including the actual vs. nominal focal length of lenses. I think the best you could say Kossi, is that two lenses of the same design, from the same manufacturer will have the same DOF at the same aperture. You could also safely say that for a given film size, print size, crop and viewing distance all 35mm lenses at f:4 will have greater DOF than all 90mm lenses at f:4. But different lenses from different manufacturers of the same nominal focal length can differ slightly in their DOF. I'll try to post some examples from the 35/1.2, 35/2 Asph, 35/2 Biogon and 35 C-Biogon, 35/2 Pentax screw-mount etc. over the weekend.

Ben
 
kossi and ben, i think it would be interesting to see more examples of these two lenses (and others since ben is flush with 35's 🙂) that illustrate dof configuration at or near wide open apertures.

kossi, i agree, one would think the wall in my zeiss pic would be oof, but it's not. makes me wonder: what is the three-dimensional shape of the zeiss 35/2's and cron IV's depth of field?
 
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ok

ok

That's all good. But the fact is, that two differently designed lenses from different manufacturers, of the same focal length and at the same aperture, can have significantly different total depth of field.

Thus rendering tools such as dofmaster.com as rough and crude guidelines, at best.

Benjamin Marks said:
I will try to post some more definitive pix this weekend under more controlled conditions. There are many variables in lens design, including the actual vs. nominal focal length of lenses. I think the best you could say Kossi, is that two lenses of the same design, from the same manufacturer will have the same DOF at the same aperture. You could also safely say that for a given film size, print size, crop and viewing distance all 35mm lenses at f:4 will have greater DOF than all 90mm lenses at f:4. But different lenses from different manufacturers of the same nominal focal length can differ slightly in their DOF. I'll try to post some examples from the 35/1.2, 35/2 Asph, 35/2 Biogon and 35 C-Biogon, 35/2 Pentax screw-mount etc. over the weekend.

Ben
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ampguy said:
That's all good. But the fact is, that two differently designed lenses from different manufacturers, of the same focal length and at the same aperture, can have significantly different total depth of field.
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I'd put it differently. They can have significantly different apparent depth of field.

For a serious discussion of the question, Zeiss have published this very very interesting, if rather long white paper. [link to ginormous PDF]
 
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Turtle said:
Have you seen what people pay for the 35mm V4 cron? There must be a fault in this casual test that ended up showing the ZM as having greater aparrent sharpness and smoother OOF. Prices for the V4 cannot possibly be related to some sort of mass hysteria - why would they be - Leica buyers are a very rational bunch. My hunch is that if you got in a time machine and shot this again, using starving Africans or Bosnian refugees, the V4 would indeed be the far better lens. Perhaps the V4 somehow responds better to 'crisis shots' due to the types of lines and tone you tend to find in such images?

In order to conduct a fair test, not only would you have to do side by sides on a tripod, you would also have to use a suitable subject. A burning building, natural disaster, or similar scene of carnage would show that the V4 rises to these challenges far better than the ZM at any aperture.

Put frankly, the 35 V4 is the best kept secret in the photographic world and prices will skyrocket further if all those talented pros and amateurs out there catch on, so shhhhhh. Keep talking up lenses like the ZM 35s, 35 Summarit and CV 35 2.5 and keep this gem available to the real shooters. I'm with you Benjamin - throw' em off the scent! 😉
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The V4 is somewhat over-hyped in today's market. It was a great lens for it's time and still holds up today, but is beaten in just about every aspect except size by the two Biogons and 35 Nokton 1.2, winning in distortion (except the Nokton), contrast, sharpness at f/2-5.6 and price....and let's not leave out the 35 Summarit which is quite good except it only focus's to 0.8m and is half a stop slower, for only a little more new than a used V4.

If the 35/2 and 35/1.4 ASPH had better bokeh wide open, the price of this lens would drop. But yes it 'did' have the best bokeh of any Leica 35mm lens, until the Summarit arrived. At the end of the day if someone wants a small, moderately fast Leica 35mm lens, it's tough to beat. I think most of the time people will hype the lens on forums just to try keep up the resale value when they own it, then play it down when they don't....not everyone, but some.
 
Great reading

Great reading

I have read this many times, printed it out, and even have had my kids study it, and quizzed them on it. I do agree with most of it. The parts that I don't can be discussed in another thread if anyone is interested.

As far as to the accuracy of on-line DOF tables, I fully agree with the conclusion of this document regarding those tables:

"The usual tables and calculators therefore provide some useful clues for practice, but they should not be taken too seriously."


semilog said:
I'd put it differently. They can have significantly different apparent depth of field.

For a serious discussion of the question, Zeiss have published this very very interesting, if rather long white paper. [link to ginormous PDF]
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I don't belive this is correct

I don't belive this is correct

The 35/1.2 images I have seen all have more distortion than the Summicron 35/2 v3, v4, cron asph., and of course the 35/1.4 pre-asph summilux.

The differences in bokeh, character, dof, contrast, and resolution have been discussed elsewhere ad nauseam.

leicashot said:
The V4 is somewhat over-hyped in today's market. It was a great lens for it's time and still holds up today, but is beaten in just about every aspect except size by the two Biogons and 35 Nokton 1.2, winning in distortion (except the Nokton), contrast, sharpness at f/2-5.6 and price....and let's not leave out the 35 Summarit which is quite good except it only focus's to 0.8m and is half a stop slower, for only a little more new than a used V4.

If the 35/2 and 35/1.4 ASPH had better bokeh wide open, the price of this lens would drop. But yes it 'did' have the best bokeh of any Leica 35mm lens, until the Summarit arrived. At the end of the day if someone wants a small, moderately fast Leica 35mm lens, it's tough to beat. I think most of the time people will hype the lens on forums just to try keep up the resale value when they own it, then play it down when they don't....not everyone, but some.
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ampguy said:
The 35/1.2 images I have seen all have more distortion than the Summicron 35/2 v3, v4, cron asph., and of course the 35/1.4 pre-asph summilux.

The differences in bokeh, character, dof, contrast, and resolution have been discussed elsewhere ad nauseam.
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Yes, but I actually prefer the Nokton to the 35/1.4 ASPH. It's rendering is smooth and lower contrast better for low light. Stopped down to f/1.4, it matches the Summilux on center and decreases a tad in the corners.

Amazing for the price, and you'd never get a fast 35mm with low distortion, which is why I also have the 35 Biogon C 😱 for general use.
 
Meat on the bones.

Meat on the bones.

Well, I went and shot some more with various 35's under more controlled conditions. The lenses used were each mounted on an Olympus EP-2 with an adapter on a tripod. ISO set at 100. Focus was done TTL with the camera's EVF with the camera's focus magnifier. Images were imported into Adobe Bridge and converted to DNG and then into JPGs, but not manipulated at all in PS. All pictures taken at f:2.8. The following are my notes and the numbers refer to the hash marks on the LensAllign ruler.

The trouble came when I went back to double-check the 100% crops of the C-Biogon and Cron Asph. While there were differences in the zones of acceptable focus, the way the lenses handled chromatic aberration and bokeh, made interpreting the differences in DOF highly subjective. I have posted the two crops at the end of this and you can decide for yourselves. In addition, the images below may not be at a high enough magnification to show the differences in DOF. Finally, the big surprise for me was that the OOF areas in front of the zone of best focus often had a very different quality than the OOF areas behind.

Cron Asph - At 2.8 the acceptable zone of focus is from 10 behind to 8 in front. Note that the OOFcharacter in front of best focus is "jaggier"/nissen bokeh compared to behind the zone of best focus (smoother).

4847608858_b4ba9cdc28_b.jpg


Cron IV - At 2.8 the acceptable zone of focus is from 6 behind to 15 in front. Bokeh smooth.

4846994391_17b2fa93a1_b.jpg


Nokton/1.4 SC - At 2.8 the acceptable zone of focus is from 6 behind to 7 in front. Bokeh is glow-y behind and nissen in front.

4847614566_6667ed6e41_b.jpg


Biogon/2 - At 2.8 the acceptable zone of focus is from 10 behind to 8 in front. Both smooth, but bokeh in front is harsher.

4847613220_55a1610be9_b.jpg


C-Biogon/2.8 at 2.8 the acceptable zone of focus is from 5 behind to 7 in front. Similar bokeh to its f:2 sibling.

[full photo to come]

Nokton/1.2 At 2.8 the acceptable zone of focus is from 4 behind to 10 in front. Bokeh is smooth.

4846990553_7c62570d5b_b.jpg


Ultron/1.7 - At 2.8 the acceptable zone of focus is from 14 behind to 4 in front. Chromatic aberration obvious in front.

4847610608_eb15e5f604_b.jpg


& Two Crops. First is the C-Biogon, Second is the Cron Asph

4847760738_9b240bba83_b.jpg


4847140495_a966c4fdbb_b.jpg
 
very nice, what distance is the sensor to the point of focus? just curious. Would be interesting to see the same tests done at f2, for the lenses that do f2.
 
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Distance was a little bit more than the 0.7 meter minimum as measured on the lenses' distance scales. The Ultron only focuses down to 0.9 meter so that one was a little farther away.

EDIT: In the final analysis, I think gauging the acceptable DOF is pretty subjective. But the differences between the lenses DOF, while real, don't account for the differences in DOF noticed by commentators in the first two pix in the thread. I wonder now, based on the results above, if I screwed the pooch and accidentally exposed one of those first images at f:4.
 
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It looks like you are using position 1 (or 2), at 45 deg. or so, the manual says the standard setting is position 3 - (20 deg.).

So when you are saying, for example, "15 behind to 4 in front", at your ruler position, does that translate to cm, given the ruler position you are using?
 
ampguy said:
It looks like you are using position 1 (or 2), at 45 deg. or so, the manual says the standard setting is position 3 - (20 deg.).

So when you are saying, for example, "15 behind to 4 in front", at your ruler position, does that translate to cm, given the ruler position you are using?
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No. It doesn't translate. I just wanted a way to compare the lenses. I'm math-lazy when it comes to this stuff. Here's the thing. When I go back and look at my first impressions, it is clear that I could change those numbers by a one or two count depending on a number of factors. As I say, there are differences, but when I am choosing my last good point of focus, it is a complete judgment call.
 
Ok

Ok

Thanks Ben, these are great tests. Keep them coming!

Benjamin Marks said:
No. It doesn't translate. I just wanted a way to compare the lenses. I'm math-lazy when it comes to this stuff. Here's the thing. When I go back and look at my first impressions, it is clear that I could change those numbers by a one or two count depending on a number of factors. As I say, there are differences, but when I am choosing my last good point of focus, it is a complete judgment call.
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