adapt Leica M lens for digital???????

[lct]

Advertisement (gone after registration)

It is a great lens i bought in the film days. It just needed calibration for digital and Leica did it for little money (don't recall how much) together with 6-bit coding.

[kiwidad]

1 hour ago, lct said:

It is a great lens i bought in the film days. It just needed calibration for digital and Leica did it for little money (don't recall how much) together with 6-bit coding.

I think digital had nothing to do with it! You just didn’t notice it was miscalibrated on your film pictures!

[lct]

8 minutes ago, kiwidad said:

I think digital had nothing to do with it! You just didn’t notice it was miscalibrated on your film pictures!

Do i look like a newbie that much? Was 13 years ago with my M8.2. Happened to me with a Summicron 90 too and Leica was well aware of the issue.

[kiwidad]

3 hours ago, lct said:

Do i look like a newbie that much? Was 13 years ago with my M8.2. Happened to me with a Summicron 90 too and Leica was well aware of the issue.

Not suggesting at all you were a newly BUT unless you crop and enlarge there is a wide margin of error that goes un noticed in 35 mm!

as I said I would return lens that focused that inaccurately! 
I don’t think the digital phenomenon of “calibration “ is anything more than Leica calibration standard for film not being as critical as digital. Maybe it was and you just got unlucky. So far in all my Leica lenses dating back to 1952 I see no error as bad as your picture on my m11

[bocaburger]

I once had it explained to me like thisn some years ago by an engineer involved in digital sensors:  

Imagine a shower head located centrally overhead, and the spray pattern is such that the jets of water come out not only straight down but at increasingly steep angles toward the periphery thus wetting the entire marble floor equally.  That is light rays from the rear lens element hitting film which is a smooth surface.

Now imagine we cover the shower floor from wall to wall with drinking glasses.  The farther the glasses are from the centre the more the spray (being at steeper angles) will hit the sides of the glasses and splash randomly rather than fill the glasses efficiently.  That is the light rays from the same rear lens element hitting a digital sensor which has pixels resembling little wells.  
 

To make the second example as equal from centre to corner as the first, one could replace the shower head with a different design that is perhaps larger in diameter and does not spray to the corners at such steep angles.  That is what recomputing lenses for digital is about.  (Or, one could put little funnels in the outermost drinking glasses, aimed at the steep incoming spray, to help channel the water into those glasses as efficiently as the ones toward the centre, thus obviating the need for a new shower head.  That is basically what Leica's sensor microlenses do.)

[lct]

1 hour ago, kiwidad said:

Not suggesting at all you were a newly BUT unless you crop and enlarge there is a wide margin of error that goes un noticed in 35 mm!

as I said I would return lens that focused that inaccurately! 
I don’t think the digital phenomenon of “calibration “ is anything more than Leica calibration standard for film not being as critical as digital. Maybe it was and you just got unlucky. So far in all my Leica lenses dating back to 1952 I see no error as bad as your picture on my m11

Comes from my bad English or i did not make me clear enough otherwise i don't know. Last try: It is a lens (Elmarit 90/2.8 v2) i had been using with success for many years in the film days. That very lens, as well as another one (Summicron 90/2 v3) did misfocus on my new M8.2 13 years ago. The camera was not the culprit. Both lenses have been fixed by Leica with no problem together with 6-bit coding. Now both lenses work perfectly on my M11 and M240. Just facts.

[mdarnton]

Advertisement (gone after registration)

OP said "adapt" not modify. I adapted all of my Leica M lenses, via adapters, to fit my digital "Leica", my Nikon Z5. One would need to do the same to fit them on one of the mirrorless Leica digitals.

Edited March 2 by mdarnton

[davidmknoble]

On 2/28/2025 at 3:35 PM, kiwidad said:

Reading the replies… so if someone says they modified a lens for digital it’s hogwash

I believe in general when someone says they modified a Leica M lens for digital, it means they had Leica put a new bayonet ring on with the 6-bit coding so the digital camera can read it.  Only the ‘newer’ lenses have that standard.  So, the older 24/21 ASPH f/2.8 lenses, summicron 50 v3, pre-ASPH lenses, were all for film and do not come with the 6-bit coding without modification.  Other than the Leica M 40mm lens, I am not aware of any M lens that must be taken apart and put back together differently for digital work.  There have been reissues that have a flatter plane of focus for the digital work whereas film was more forgiving, but a lens is a lens.

For the 40mm I think it was for the Leica CL film camera and I thought it needed adjusted for any other camera, but I could be wrong.  I did not mean to imply it had to be changed for digital work.

Edited March 2 by davidmknoble
Clarify 40mm

[LarsHP]

On 2/28/2025 at 9:35 PM, kiwidad said:

Reading the replies… so if someone says they modified a lens for digital it’s hogwash

I get the angle of light striking the sensor matters dues to the glass cover thicknet and I think that’s the design aspect. 
 

I saw images shot on m10 and m11 with a super angulon and the m10 had a color cast on edges. Suggests the m11 may not need the radical lens redesigns other leicas and brands need in the glass!

There is a layer of glass in front of the sensor, and that can definitely cause some problems that the lenses designed for film didn't take into account. This is also the reason why digital Leica M cameras have a substantially thinner sensor glass (around 1mm) than other systems, particularly M4/3 and Sony (around 2.5mm). For this reason, some M lenses perform much worse on non-M cameras than they do on the cameras they were designed to be used with. There are lots of information about this on the net, but the basic issue is that when the angle of light is steep, bad things happen such as smearing and field curvature (plane of focus bends outward well away from the center).

[kiwidad]

19 hours ago, LarsHP said:

There is a layer of glass in front of the sensor, and that can definitely cause some problems that the lenses designed for film didn't take into account. This is also the reason why digital Leica M cameras have a substantially thinner sensor glass (around 1mm) than other systems, particularly M4/3 and Sony (around 2.5mm). For this reason, some M lenses perform much worse on non-M cameras than they do on the cameras they were designed to be used with. There are lots of information about this on the net, but the basic issue is that when the angle of light is steep, bad things happen such as smearing and field curvature (plane of focus bends outward well away from the center).

Agreed. But there is nothing you can do to fix this on a pre digital lens. The m11 reigned supreme with these older lenses as has been shown in reviews and tests with its incredibly thin sensor glass. This is really only relevant to wider lenses though as standard thru telescope don’t have this exit angles!

 

[kiwidad]

On 3/2/2025 at 6:49 AM, davidmknoble said:

For the 40mm I think it was for the Leica CL film camera and I thought it needed adjusted for any other camera, but I could be wrong.  I did not mean to imply it had to be changed for digital work.

I think this is generally believed to have been a marketing ploy to keep M owners buying the more expensive glass.

[LarsHP]

12 hours ago, kiwidad said:

Agreed. But there is nothing you can do to fix this on a pre digital lens. The m11 reigned supreme with these older lenses as has been shown in reviews and tests with its incredibly thin sensor glass. This is really only relevant to wider lenses though as standard thru telescope don’t have this exit angles!

1. Yes, there are actually some tricks one can do. Adding a plano-convex filter with the appropriate strength to lenses made for film can mitigate the outward bending field curvature.

2. The reason M11 works so well isn't an especially thin sensor glass thickness, but that it uses modern back-side illuminated sensors, and these have pixel wells that allow light at a steeper angle than the older types.

3. The issue isn't just regarding wide angle lenses. Some normal and even telephoto lenses can create these issues.

4. So, when Leica says they have modified the lens design of - say - their 28mm Summicron-M Asph lens, there are actual and real optical reasons for doing it.

The issue seems to be related to both exit pupil distance and aperture. Superfast lenses will often have more problems than slower lenses (having the same focal length).

[davidmknoble]

20 hours ago, kiwidad said:

I think this is generally believed to have been a marketing ploy to keep M owners buying the more expensive glass.

So, interestingly, the 40 f/2.8 lens had less than 500 made, which means it doesn't matter.  But there were about 54,000 of the 40mm f/2.0 made. The only drawback I see is that there is no 40mm frameline to accurately frame the image, but I think it would work.

[lct]

Both Elmarit-C 40/2.8 and Summicron-C 40/2 work normally on digital. Same for Elmar-C 90/4. Their sloped focus cams is probably less accurate than regular ones but i haven't got misfocus issues with them so far, even on the M11. FWIW.

[Jamison]

On 3/4/2025 at 10:07 PM, kiwidad said:

I think this is generally believed to have been a marketing ploy to keep M owners buying the more expensive glass.

The 40mm for the CL was not recommened for M cameras because the focus would not be consistent throughout the range.  I don't believe there was a fix.  We, at Leica, Rockleigh, in product management did not recommend to use the 40mm on M cameras at the time the CL was selling.  I get the feeling that it was so close that most people did not notice.  I did not run across a customer complaint while the 40mm were being sold.  It could be that repair had a different response.

Edited March 31 by Jamison

[sandro]

The idea to adjust lenses for accurate focus is not so strange at all. Leica Wetzlar has some information on the website that may clarify at least some of it: M-System Service | Leica Camera AG and then 'Lens adjustment'.

Lex

[kiwidad]

On 4/1/2025 at 10:12 AM, sandro said:

The idea to adjust lenses for accurate focus is not so strange at all. Leica Wetzlar has some information on the website that may clarify at least some of it: M-System Service | Leica Camera AG and then 'Lens adjustment'.

Lex

I fully understand the wear aspect, however, this essentially states that Leica didn't critically adjust lenses for focus back in the film days! Or is there an even better way to adjust critical alignment now?

I recall comments over the years saying you had to send a body and lens back together to achieve perfection but that it may not be possible across a spread of lenses! That was what theLeica rep told me back in 1987 in the store I worked in that was an authorized dealer.

If you need this critical focus I suggest a visoflex or stop down the lens as the accuracy they claim isnt really doable thru a rangefinder! I am not dogging leica here just being honest. I find the eyepiece magnifier makes a world of difference at 50mm or longer focal lengths but even then the viso is the critical way!

And really this all depends on the need! do you look at your prints on a computer screener enlarge to huge dimensions and stand over them with a magnifying glass?

depth of field of subject with a 50 SUMMILUX at f1.4 and 10 feet aways is? you want a nose or ear in focus? if your off who notices?

[LarsHP]

18 hours ago, kiwidad said:

I fully understand the wear aspect, however, this essentially states that Leica didn't critically adjust lenses for focus back in the film days! Or is there an even better way to adjust critical alignment now?

I recall comments over the years saying you had to send a body and lens back together to achieve perfection but that it may not be possible across a spread of lenses! That was what theLeica rep told me back in 1987 in the store I worked in that was an authorized dealer.

If you need this critical focus I suggest a visoflex or stop down the lens as the accuracy they claim isnt really doable thru a rangefinder! I am not dogging leica here just being honest. I find the eyepiece magnifier makes a world of difference at 50mm or longer focal lengths but even then the viso is the critical way!

And really this all depends on the need! do you look at your prints on a computer screener enlarge to huge dimensions and stand over them with a magnifying glass?

depth of field of subject with a 50 SUMMILUX at f1.4 and 10 feet aways is? you want a nose or ear in focus? if your off who notices?

I feel confident that modern high resolution sensors pose lower tolerances than what was needed in the analog days. In addition, we are seeing much more shallow depth of field photography today than we did several decades ago. When I shot M4-2 with my 35mm Summicron (and other lenses) in the analog era, I usually stopped down to at least f/2.8 for best sharpness. Only is very low light, I would shoot wide open, and in those cases, I would use a fast and grainy film, somewhat masking lack of ultimate sharpness. Today, I am using 50mm lenses at f/1 and f/1.2 at low ISO, often at shorter focus distances, making precise focus crucial.

[kiwidad]

50 minutes ago, LarsHP said:

I feel confident that modern high resolution sensors pose lower tolerances than what was needed in the analog days. In addition, we are seeing much more shallow depth of field photography today than we did several decades ago. When I shot M4-2 with my 35mm Summicron (and other lenses) in the analog era, I usually stopped down to at least f/2.8 for best sharpness. Only is very low light, I would shoot wide open, and in those cases, I would use a fast and grainy film, somewhat masking lack of ultimate sharpness. Today, I am using 50mm lenses at f/1 and f/1.2 at low ISO, often at shorter focus distances, making precise focus crucial.

And you can focus f1 accurately with a rangefinder patch? Impressive!

[Advertisement]

Hallo,

Look here: Leica M

[Vanillasludge]

On 3/1/2025 at 9:11 AM, UliWer said:

Even though the explanation of the „natural depth“ of the film emulsion is right, much more important is how we look at the results of photography with film and with a digital sensor. With film it takes at least some hours until you see the results - usually days or weeks. You don‘t remember how exact your focus was when you took the photo. The results from a digital sensor are available immediately and can be compared much easier than with film. Who ever looked at his photos with film with a magnification that equals a 100 or 200% magnification by his software on a screen with a distance of less than a meter?

That‘s the true reason why digital photography is much less forgiving. Older lens designs which for example showed focus shift did so already with film, but people didn’t notice it or lived with it. With digital photography people started to notice the fault and complained, so the lensmakers had to react and find ways to avoid focus shift. Or they used smaller tolerances for calibration, or used lens designs which made the light hit the sensor in less flat angles etc.

The „adaptation for digital“ is an adaptation to less forgiving customers who use digital photography.  

 

This is absolutely true. In my darkroom days I never knew anything about focus shift until I started using a grain focus magnifier on my enlargements.

Once I had seen it on my Summicron 35 v4 I couldn’t unsee it.  I even asked Leica what was going on and they explained the entire phenomenon to me.  
 

Print an image at any reasonable size from any modern digital Leica and you won’t notice any artifacts today that we didn’t see in the 80’s. (Excepting color shifts).