Zero Leica lens

[jaapv]

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6 hours ago, IkarusJohn said:

Interesting - you’re saying there is variation between cameras in depth of focus?

No. Although now that you mention it, DOF varies slightly with pixel count. 

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[UliWer]

Does a camera with more pixel show wider or smaller DOF?

You may say wider since more pixel may resolve also something which is slightly out of focus.

Or you may say the DOF becomes smaller with more pixel as they reveal the difference between in and out of focus better.

When the 1:2.5/5cm Hektor was introduced Max Berek wrote that users shouldn‘t be afraid that DOF was too small as the lens was so „soft“ that it concealed the differences. 

 

[DadDadDaddyo]

55 minutes ago, Al Brown said:

It’s not a tragedy until it’s zero Leica lenses and zero Leica bodies.

Or vice versa.... 8^p

[SrMi]

5 hours ago, jaapv said:

No. Although now that you mention it, DOF varies slightly with pixel count. 

Does it vary? Even if the magnification is the same (same output size, same sensor size)?

[jaapv]

Slightly due to better definition at the same magnification. At 100% certainly. When a sensor has a higher pixel count (e.g. 60 vs 24) at the same sensor size the output will be different. 

[Warton]

7 hours ago, roelandinho said:

While I agree with you and O1af, I just want to mention (because I think some people may get confused by this), the focus shift is a property of the lens, and refers to the plane of best focus shifting backwards as the aperture is closed. If you put the same lens on different cameras, the focus shift doesn't change. What does vary is the amount of error you can experience by this (if you blindly trust the rangefinder). 

• Worst case: your camera system (sensor + lens combination) already back-focuses at full aperture because of calibration issues. This back-focus will only get worse as you stop down because the plane of focus moves backwards. (Obviously depth-of-field will increase also which makes this less bad, but still the background will always be sharper than your subject...)
• Better, but not ideal for most people: your camera system focuses perfectly at full aperture. This is ideal if you only use the lens at max aperture, but the focus shift will cause significant back-focus at all other apertures. 
• Best for most people: perfect focus at approx. one stop down from full aperture. This will cause slight front-focus at full aperture (much preferable to back-focus if you photograph a subject against a background), and also a bit of back-focus at smaller apertures. It's a compromise that minimizes the "largest possible focus error" you can experience when trusting the rangefinder. I personally still overrule the rangefinder at smaller apertures in this case to correct the back-focus. 
• Last option: perfect focus at a small aperture. This leads to significant front-focus at large apertures and is probably not a useful option, unless you only shoot landscapes stopped down. 

In all these cases the focus shift of the lens is the same, but the problematic effects you experience when blindly following the rangefinder can be greater or smaller depending on the calibration and your personal usage pattern. 

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?

[SrMi]

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5 hours ago, IkarusJohn said:

I’m still not with you.

The focal plane is at the sensor - it used to be marked on the top deck.  How does that move when using the rangefinder?

The depth of focus is the depth of the plane of best focus at the focal plane - not such a problem with the thick emulsion on film, more of a problem with a digital sensor.  It’s quite different from depth of field and focus shift.  Focus shift is when the image projected by the lens is at the focal plane at, say, f/2 and then moves away as the lens is stopped down, making the image at the focal plane out of focus, until the the depth of field brings the image back into acceptable focus - at f/5.6 or smaller.

Famously a problem with the 35 Summilux ASPH (first version) and the f/1 Noctilux.

Now, I know that some wil quibble with that explanation, but my point is, I’m not sure I follow how the rangefinder has any impact on the lens, or the depth of focus, or the focal plane, for that matter.  The focal plane stays in the same place.  It’s the plane of best focus that shifts as the lens is stopped down.  That’s the problem …

There are two meanings of focal plane: 

a) Focal point of a lens, i.e., film or sensor plane

b) Plane where objects are in focus (at some distance from the camera).

I was referring to the imaginary plane of perfect focus, which moves with the lens's focus ring and is set by the rangefinder.

I misread your depth-of-focus as depth-of-field. Thanks for explaining it.

The focus shift also shifts the plane of perfect focus, as does a discrepancy (mechanical tolerance) between the rangefinder mechanism and the lens focus. It is conceivable that the focus shift overlaps with the difference caused by mechanical tolerance.

 

[SrMi]

13 minutes ago, jaapv said:

Slightly due to better definition at the same magnification. At 100% certainly. When a sensor has a higher pixel count (e.g. 60 vs 24) at the same sensor size the output will be different. 

Are you saying that the higher resolution is "sharper" at the plane of perfect focus at the same magnification, and, therefore, the DOF varies when compared to the lower resolution?

I have never seen an analysis or study that shows higher DOF with smaller resolutions alone.

The output size does not change with the resolution.

Edited May 1, 2024 by SrMi

[jaapv]

An 18 MP sensor has the same output size as a 60 MP one? What do we need all that memory for then? 

[SrMi]

29 minutes ago, jaapv said:

An 18 MP sensor has the same output size as a 60 MP one? What do we need all that memory for then? 

The output size is defined by the user, not by the sensor.

The question is: why have a higher resolution when, for a given output, a lower resolution would suffice? The answer is better IQ and the possibility to print larger at a later stage.

[Fred Miranda]

On 4/29/2024 at 6:30 PM, lct said:

Zero Leica lens in my bag. First time it happens to me in half a century. Not that i dislike Leica lenses but 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. Only issue is 0.9m MFD but a close focus adapter fixes the issue in LV mode.
• Nokton 35/1.4 SC v2, sort of Summilux 35/1.4 v2 w/o the drawbacks of it. I still use the Summilux but for glow only at f/1.4.
• Nokton 75/1.5. Same comment more or less.
Incredible that i can cram those fast lenses with a 61mp camera and its EVF in a tiny bag BTW. Like in my youth with M4, K25 and f/2 or f/2.8 lenses but i could not dream of carrying a bulky 75/1.4 plus an optical Visoflex in the same bag then. The Leica spirit at its best in Japan 🙂
Do we need really monstrous 90/1.5 and 75/1.25 enses, let alone Godzilla SL lenses?
I'll stop here because I don't want to add my voice to the LUF's chorus of wailers 😄

Your list of lenses that work well on high megapixel sensors is great. But, saying the Leica M11 reduces focus shift might not be accurate. It's more likely that the M11's rangefinder adjustment just suits your Zeiss 50/1.5 Sonnar better at f/2 compared to your previous camera.

[jaapv]

49 minutes ago, SrMi said:

The output size is defined by the user, not by the sensor.

The question is: why have a higher resolution when, for a given output, a lower resolution would suffice? The answer is better IQ and the possibility to print larger at a later stage.

The output in the end  However the input of more data will result in a reduction that contains more information than a native smaller file;  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) Analog to a Monochrom file that despite an identical pixel count will contain better detail  by skipping interpolation thus contains more information with the same pixel count  

 

[lct]

25 minutes ago, Fred Miranda said:

[...] saying the Leica M11 reduces focus shift might not be accurate.

Quoting me accurately might help. I said "reduces focus shift, or the effect of it". Is it more (or less?) accurate then?

[Fred Miranda]

9 minutes ago, lct said:

Quoting me accurately might help. I said "reduces focus shift, or the effect of it". Is it more (or less?) accurate then?

What I meant is that 'your' M11 produces these results because its rangefinder is calibrated to optimize performance for your lens at f/2. Other rangefinder models may yield identical results if similarly adjusted. By the way, I found the Zeiss 50/1.5 Sonnar's focus shift to be quite extreme. It's a shame because I really like the way it renders wide open. However, when stopped down to f/2 or f/2.8, much of that magic diminishes. Therefore, I didn't find it to be an ideal lens for rangefinder focusing. The CV 35/1.4 II also produces some focus shift, although not as pronounced.

[IkarusJohn]

52 minutes ago, jaapv said:

The output in the end  However the input of more data will result in a reduction that contains more information than a native smaller file;  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) Analog to a Monochrom file that despite an identical pixel count will contain better detail  by skipping interpolation thus contains more information with the same pixel count  

All true.  But not to be confused with focus shift, which is a property of the lens.  Increased resolution can’t correct an out of focus image projected onto the sensor.  You’ll get a more detailed out of focus image, but if it’s out of focus when it comes from the lens, unless the sensor moves, 60MP or 100MP won’t correct focus shift.

[lct]

13 minutes ago, Fred Miranda said:

[...] I found the Zeiss 50/1.5 Sonnar's focus shift to be quite extreme [...]

Not my feeling any more but my ZM 50/1.5 has ben calibrated to be accurate at f/1.5. Focus shift (or effect of it?) can be seen mainly at about f/4, f/5.6.

[Danner]

There are many great lens options, I thought highly of both my 35/1.4 SC Nokton and 35/2.8 C-Biogon.  However, Leica is and has been about the lenses.  And, I'd miss using the Leica lens names when discussing them.  Weird, I know...

[SrMi]

On a related note:

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

Comparing Rangefinder and SLR 50mm Lenses

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Hallo,

Look here: Leica M

[jaapv]

Not - nobody suggested that the sensor moves...  Except when it is being adjusted by a technician., The symbol on the top deck indicates the approximate position of the sensor. The focal plane is the virtual sharpest surface of the image projected by the lens which should ideally coincide with the surface of the sensor.

9 hours ago, IkarusJohn said:

The focal plane is at the sensor - it used to be marked on the top deck.  How does that move when using the rangefinder?

 

[jaapv]

1 hour ago, IkarusJohn said:

All true.  But not to be confused with focus shift, which is a property of the lens.  Increased resolution can’t correct an out of focus image projected onto the sensor.  You’ll get a more detailed out of focus image, but if it’s out of focus when it comes from the lens, unless the sensor moves, 60MP or 100MP won’t correct focus shift.

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.