Zero Leica lens

[mujk]

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4 hours ago, Warton said:

It looks like a wealth of knowledge so I am trying to post the questions I asked months ago which seemed nobody can answer.

I have two digital M bodies, let's denote them A and B.

And I have 5 M mount lenses (3 are Leica's, 2 are LLL's), let's denote them 1,2,3,4,5.

For the combination of A1, and A2, I can identify obvious focus shifts at f/2.8 and f/4. But NO focus shift with combination of A3, A4 and A5.

Also I don't see focus shifts with combination of B1, B2, B3, B4, B5.

So please enlighten me, what's the problem or root cause here. Is lens 1 and 2 are bad, or camera A bad, or both?

More detailed answers can be found in other posts in this thread, but to answer your question directly: The rangefinders of cameras A and B are adjusted slightly differently so that the focus shift of lenses 1 and 2 becomes visible in camera A but not in B. Lenses 3, 4 and 5 have less or no focus shift, so for them there is no difference between A and B.

 

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[roelandinho]

4 hours ago, Warton said:

I have two digital M bodies, let's denote them A and B.

And I have 5 M mount lenses (3 are Leica's, 2 are LLL's), let's denote them 1,2,3,4,5.

For the combination of A1, and A2, I can identify obvious focus shifts at f/2.8 and f/4. But NO focus shift with combination of A3, A4 and A5.

Also I don't see focus shifts with combination of B1, B2, B3, B4, B5.

So please enlighten me, what's the problem or root cause here. Is lens 1 and 2 are bad, or camera A bad, or both?

For A1 and A2 you can "identify obvious focus shifts at f/2.8 and f/4". What do you mean exactly?

• Did you just notice back-focus at these apertures?
• Or did you notice the subject at f/4 being slightly softer (less in focus) than at f/2.8?
• Or did you take a picture at f/2.8 and f/4 where you can see the entire focus field (e.g. photographing a grass field) and saw that the plane of best focus was further away at f/4 than at f/2.8?
• Or something else? 

It could be that lenses 1 and 2 do indeed focus shift, and that the calibration of camera A is such that the effect is more obvious in your usage than with camera B (see my previous post). 

[Olaf_ZG]

1 hour ago, SrMi said:

On a related note:

(Looks at Sonnar 50/1.5 and four Leica M lenses)

Comparing Rangefinder and SLR 50mm Lenses

Srdjan, nice looking graphs but honestly I don’t care.

I own both a sonnar and a lux. The sonnar is so great with still lifes and nudes or soft portraits and it outplays the lux as the latter is too sharp. I don’t care about graphs.

Convince me with photos why the sonnar is best (no need to convince me, but may be others).

I own both the lux and sonnar. None of them I will ever sell. They are simply wonderful.

[SrMi]

3 minutes ago, Olaf_ZG said:

Srdjan, nice looking graphs but honestly I don’t care.

I own both a sonnar and a lux. The sonnar is so great with still lifes and nudes or soft portraits and it outplays the lux as the latter is too sharp. I don’t care about graphs.

Convince me with photos why the sonnar is best (no need to convince me, but may be others).

I own both the lux and sonnar. None of them I will ever sell. They are simply wonderful.

Olaf, the linked article was never meant to be the ultimate decision but to understand the lens's characteristics that can be measured. We can only grasp the subjective (e.g., how the lens draws) by reading the owner's experience or by using the lens ourselves.

IMO, companies are too often focused on making lenses nowadays with the only goal of having perfectly sharp corners.

[UliWer]

vor 3 Stunden schrieb jaapv:

that means that the amount of detail may be similar on output, the quality of detail will be higher and that will affect DOF ( slightly like I said)

How does a higher resolution affect DOF?

With more "quality of detail" will you see something which is slightly unsharp - at the edge of DOF - on a lower resolving sensor as sharp, or will you notice that something is not exactly sharp earlier than on a lower resolving sensor?

Does higher resolution increase DOF or does it reduce DOF?

[Olaf_ZG]

12 minutes ago, SrMi said:

Olaf, the linked article was never meant to be the ultimate decision but to understand the lens's characteristics that can be measured. We can only grasp the subjective (e.g., how the lens draws) by reading the owner's experience or by using the lens ourselves.

IMO, companies are too often focused on making lenses nowadays with the only goal of having perfectly sharp corners.

Srdjan, when I photograph a sensual image (perfect subject for the sonnar) I care about the results, the feeling, the impact on me, when reviewing the result image taken.

Rendering, to call it like this, is to me the most important factor of buying a m-mount lens. For me, the sonnar is best, followed by the 50lux, and then the 28 summaron.

Had the nokton 35 sc, but it didn’t work. Like the 75 nokton though I might change it for a SL similar f/l.

At my work, graphs are a daily part, and I understand them. Never understood the graphs for lenses… but then, to me photography is about feeling, not about mathematics.

[SrMi]

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27 minutes ago, Olaf_ZG said:

Srdjan, when I photograph a sensual image (perfect subject for the sonnar) I care about the results, the feeling, the impact on me, when reviewing the result image taken.

Rendering, to call it like this, is to me the most important factor of buying a m-mount lens. For me, the sonnar is best, followed by the 50lux, and then the 28 summaron.

Had the nokton 35 sc, but it didn’t work. Like the 75 nokton though I might change it for a SL similar f/l.

At my work, graphs are a daily part, and I understand them. Never understood the graphs for lenses… but then, to me photography is about feeling, not about mathematics.

Olaf, thank you for your comments about the lenses mentioned above, and much appreciated.

Knowledge, even when it is only graphs, never hurts. The problem is what we do with that knowledge.

[IkarusJohn]

2 hours ago, jaapv said:

My post related to DOF, not focus shift.  Nobody said anything about resolution correcting focus shift. I wonder where these ideas of a moving sensor or resolution correcting focus shift  come from. The whole point is that focus shift is a given property of a lens, which should be hidden in DOF as best as possible by an exact adjustment of the focus at one stop from open. For this both  lens and sensor-flange distance must be adjusted as precisely as possible. 

I think you need to read back in the thread. 

[jaapv]

I think you misread completely. Somehow you mixed up focal plane and sensor position.

[Danner]

8 hours ago, Warton said:

It looks like a wealth of knowledge so I am trying to post the questions I asked months ago which seemed nobody can answer.

I have two digital M bodies, let's denote them A and B.

And I have 5 M mount lenses (3 are Leica's, 2 are LLL's), let's denote them 1,2,3,4,5.

For the combination of A1, and A2, I can identify obvious focus shifts at f/2.8 and f/4. But NO focus shift with combination of A3, A4 and A5.

Also I don't see focus shifts with combination of B1, B2, B3, B4, B5.

So please enlighten me, what's the problem or root cause here. Is lens 1 and 2 are bad, or camera A bad, or both?

As a retired intellectual property attorney, I respect the way you structure your post.

[IkarusJohn]

6 hours ago, jaapv said:

I think you misread completely. Somehow you mixed up focal plane and sensor position.

Oh boy. Well, find disagreement where you would like to Jaap. If you actually read my post on this issue, you might find we agree. 

I can’t think of a moving sensor, other than IBIS. Why would the focal plane move?

I’ll leave you to this disagreement. 
 

[jaapv]

A sensor is not a focal plane  Nobody said that a sensor moves…. The only one who brought this up is you...

The focal plane is the collection of focus points at the distance between your camera lens and the perfect point of focus. A sensor is, well, a sensor. When the two coincide your image is in focus. 

https://mastinlabs.com/blogs/photoism/understanding-focal-plane-in-photography

[Alberti]

On 4/30/2024 at 3:30 AM, lct said:

Zero Leica lens in my bag. [ ] For the first time i prefer ZM or VM lenses.
• Sonnar 50/1.5 thanks to the M11 that reduces focus shift, or the effect of it. Now the Sonnar has become my favorite 50 for portraiture, replacing my good old Summilux 50/1.4 v2 or v3 in a smaller package.

A lot of talk about the sensor 'as a flat thing' more or less at the same place as 'the hopeful flat focal plane'.

1) Not much about why the M11 should be thanked for 'improving' the Sonnar lens, apart from calibration. I am sure the example of lct is one of more.

I have the M10R. I cannot explain why several lenses look different on this sensor compared to the M240 I had. I can guess. [The micro-prisms of the M240 sensor have a different geometry, are higher, and therefore more discriminating.] I can guess more. That is of no use. I cannot document it.

2) The second remark was the weight/size. I totally agree. Yes I understand - I had a Black Chrome, heavier than my camera, so it felt like a Godzilla. Why make it like that? Brass. Why? Why make the hood 1/5 of the weight of some lenses? Sure I like my Summicrons in chromed brass. But 500g is different. Then it becomes lead. 

Size is even more important to me, as that means handling, ergonomics. I love small lenses. I still have to learn the feeling of larger lenses, like my Summilux 35/A. [ @Joeri is the man to talk as an expert about handling, feeling].

I have already had many zero Leica days. You know? I like them.

[hansvons]

14 hours ago, Olaf_ZG said:

nokton 35 sc

The 35mm Nokton f1.4 SC is a wonderful lens on film, especially BW, and pretty much copies the Steel Rim’s rendering. On digital it’s too cool, too vignetty, too everything.

[Warton]

21 hours ago, Danner said:

As a retired intellectual property attorney, I respect the way you structure your post.

As a not-yet-retired data scientist, quantitative researcher, statistician, I always like to structure the variations using mnemonics to cover all the permutations/combinations in a simplified manner to avoid the unnecessary deviations from the topic.

For example, if I had said M11 with lens Summicron 35, and Noctilux 50/1.2 were having focus shift, while M10 with these didn't have, people here would have started to argue why M10 is better than M11, completely forgot about the focus shift technicality.

So the notion of A and B, with 1,2,3,4,5 keeps things discreet.

 

Edited May 2, 2024 by Warton

[lct]

50 minutes ago, Warton said:

As a not-yet-retired data scientist, quantitative researcher, statistician, I always like to structure the variations using mnemonics to cover all the permutations/combinations in a simplified manner to avoid the unnecessary deviations from the topic.

For example, if I had said M11 with lens Summicron 35, and Noctilux 50/1.2 were having focus shift, while M10 with these didn't have, people here would have started to argue why M10 is better than M11, completely forgot about the focus shift technicality.

So the notion of A and B, with 1,2,3,4,5 keeps things discreet.

This retired lawyer feels completely lost here.
If camera A (M11 or whatever) shows less focus shift than camera B (M10 or whatever) with the same lens at the same aperture, same subject distance and same everything else, the difference can only come from the camera, not the lens, right?
Only question can be what kind of difference and where it comes from in the camera, not the lens again.
Too bad i didn't defend my thesis on causality 😄

Edited May 2, 2024 by lct

[roelandinho]

44 minutes ago, lct said:

This retired lawyer feels completely lost here.
If camera A (M11 or whatever) shows less focus shift than camera B (M10 or whatever) with the same lens at the same aperture, same subject distance and same everything else, the difference can only come from the camera, not the lens, right?
Only question can be what kind of difference and where it comes from in the camera, not the lens again.
Too bad i didn't defend my thesis on causality 😄

Camera A cannot show less focus shift than camera B with the lens at the same aperture, because it's impossible to measure focus shift by looking at just one aperture. The only thing you can compare at a singe aperture is the amount of (focus-)error at that aperture. The error at that single aperture can be different for both cameras with the same lens, depending on camera calibration. For example, camera A could show more back-focus at f/2.8 than camera B at f/2.8. 

The focus shift of the lens is however the same on both cameras. To see this, take a series of pictures through all aperture values of a flat grass field or some other textured surface so you can clearly see the entire focus field. You should be able to determine the plane of best focus (a curve in the grass or texture) in each picture. You'll notice the focal plane moves further from the camera with each smaller aperture stop. 

Edited May 2, 2024 by roelandinho

[lct]

1 minute ago, roelandinho said:

The focus shift of the lens is however the same on both cameras

I must have leant this 20+ years ago thank you although i don't recall everything but what interests me is what in-camera difference(s) can explain that focus shift doesn't look the same with the same lens and everything else when the only variable is the camera.

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Hallo,

Look here: Leica M

[jaapv]

As said multiple times in this thread: you were just lucky with the adjustment on this specific camera and lens.

[roelandinho]

15 minutes ago, lct said:

I must have leant this 20+ years ago thank you although i don't recall everything but what interests me is what in-camera difference(s) can explain that focus shift doesn't look the same with the same lens and everything else when the only variable is the camera.

The main differences in camera calibration are 

1. rangefinder calibration: if you’re focusing both cameras according to the rangefinder on the same subject, the resulting distance setting on the lens could be slightly different because of different rangefinder adjustment. 

2. flange focal distance (distance between the lens mount and the sensor or film plane): even when the lens has the same distance setting on both cameras, the focal plane could be slightly different (further or closer) because of varying flange distance between cameras. 

Both of these vary slightly between cameras, also between samples of the same model. 
 

But again, the focus shift is the same for both cameras. It is the focus accuracy at single apertures that differs. 
 

 

 

Edited May 2, 2024 by roelandinho