Why few Leica lenses are the sharpest lenses in the world?: Beginners Questions Forum: Digital Photography Review (2024)

https://wordpress.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7/

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

Yet I still see sharpness chart for each aperture. That's why I doubt my title. Can anyone tell me about this? If it's true that Leica has the sharpest lens, how come? They are much smaller and I doubt that they can support high mega pixels.

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Sunshine7913 wrote:

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

A wide aperture lens can be harder to design well than a lens with a smaller aperture: a fast lens might require more elements, better coatings, and exotic formulations of glass, or aspheric elements, to correct the light that enters the lens far from the central axis.Many optical defects increase quickly the farther from the center axis of the lens you get, and so, aless demanding f/stop value makes lens design simpler; this is also one of the reasons why stopping a lens down usually improves its optical performance: you are cutting out a lot of that aberrated off-axis light.

Now imagine that they put all of that effort, using exotic glasses and coatings, aspherics, etc., but don't need to correct for the aberrations that come from using a wide aperture, then wouldn't the smaller lens be all that better?

Consider a simple pinhole 'lens'. It is just a tiny aperture without any glass whatsoever. This 'lens' has no spherical aberration, flare, barrel distortion, or most any other optical defect: it is close to being a perfect lens in just about every aspect, except for the fact that it might be f/500 and generates tons of diffraction.

However, Leica is also known for having excellent quality control in manufacture, which can help.

3

I don't know if the practice persists but Leica used to put about ten years of R+D in between each model release. They don't tend to sell a camera until they have got it as good as they can get it. They have a long standing rep for the highest of standards and the glass is no exception. Realize also that more lens elements don't necessarily equate to a higher quality image. The more you work the image the more complex the math becomes and pretty soon each new element is there to correct the new errors introduced by the last correction. Leica has been at this for a long time now with it's first 35mm camera coming out in 1925 and perfecting it's lens artistry ever since. Because of it's high end reputation I would jump to the conclusion that rather than having to put out new specs for the sake of PR every year that they have simply fine tuned and tweaked designs that have been already reliable for many decades.

A neighbor of mine managed Australian Leica distribution for a few years there. If I see him soon I will see if I can get his skinny on the story for you.

Sunshine7913 wrote:

https://wordpress.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7/

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

Yet I still see sharpness chart for each aperture. That's why I doubt my title. Can anyone tell me about this? If it's true that Leica has the sharpest lens, how come? They are much smaller and I doubt that they can support high mega pixels.

Almost no consumer camera lenses are diffraction limited. A diffraction limited lens is one which resolves as much as is physically possible for that aperture: its resolution is limited by the diffraction of light, rather than by lens aberrations.

It is certainly possible to build diffraction limited lenses, but that usually applies to the central part of the field of view only. Astronomical telescopes are almost always diffraction limited, but they cover only a very small field of view.

The nearest you will get to a diffraction-limited camera lens is in the long focal lengths (because they cover a relatively small field of view). I remember that back in the 1990s an independent organisation did some very thorough and professional lens tests on a large number of camera lenses and their highest scoring lens for resolution was a Canon 200mm f/1.8, which beat all the shorter focal length lenses including Leica, Zeiss, Canon, Nikon and many others. The fact that it was 200mm is significant - it did not need to be designed to cover a wide field of view.

Their tests also found that several f/2 lenses by both Leica and Zeiss were higher resolution than all the faster lenses of the same focal length. It's easier to design an f/2 lens of very high resolution if you have to cover the field of field needed for a 50mm (or thereabouts) lens.

The moral is: in general you cannot judge the resolution of a camera lens by the size of its aperture (unless it is diffraction limited and almost no camera lenses are).

1

Because Leica are consistently the very best lens manufacturer in the world.

Their lenses are not one sharp, but handle flare, direct sun in a beautiful way, they are built better than any other and are also almost free of any (or much) sample variation... From my experience.

5

Sunshine7913 wrote:

https://wordpress.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7/

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

Yet I still see sharpness chart for each aperture. That's why I doubt my title. Can anyone tell me about this? If it's true that Leica has the sharpest lens, how come? They are much smaller and I doubt that they can support high mega pixels.

If you spend $7000 on a lens (which is what the Leica f/2 APO Summicron costs) you would expect it to be something special. The reason that it's the sharpest lens in the world is simply that Leica has decided it was going to be, spared no expense in achieving that aim and is happy to pass that cost onto the customer. Why is the lens smaller than the Zeiss and Sigma? Four reasons.

One is that the lens is designed for a shorter lens register (Leica M-mount). This means that a 50mm lens can use a symmetrical design, which naturally cancels out aberrations. 50mm lenses for SLRs can't have a fully symmetric construction. Traditionally they were modified symmetric, but the Otus started a trend for designing them as retrofocal, like a wide angle lens, which makes them larger.

Second, the lens is only an f/2, whilst the others are f/1.4. That means it is intrinsically a more relaxed design.

Third, the high price allows Leica to include ground-to-shape aspheric elements as opposed to the hybrid (plastic aspheric on glass element) or moulded aspheric common in cheaper lenses. This allows a very precisely tailored profile which can ensure better performance.

Fourth, one of the major constraints in lens design is manufacturing tolerance. If you know there will be a dimensional variation in manufacture, then the lens needs to be designed to produce acceptable results over that full range of variance. That compromises the peak performance. If you know that you can manufacture with very tight tolerances, you can design for that peak performance. If you're charging $7000 for a small and simple lens, you can spend the money tightening the tolerances.

In the end, you're getting what you pay for.

Tom Axford wrote:

Sunshine7913 wrote:

https://wordpress.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7/

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

Yet I still see sharpness chart for each aperture. That's why I doubt my title. Can anyone tell me about this? If it's true that Leica has the sharpest lens, how come? They are much smaller and I doubt that they can support high mega pixels.

Almost no consumer camera lenses are diffraction limited.

Most are at f/22.

A diffraction limited lens is one which resolves as much as is physically possible for that aperture: its resolution is limited by the diffraction of light, rather than by lens aberrations.

It is certainly possible to build diffraction limited lenses, but that usually applies to the central part of the field of view only. Astronomical telescopes are almost always diffraction limited, but they cover only a very small field of view.

The same applies to macro work.

The nearest you will get to a diffraction-limited camera lens is in the long focal lengths (because they cover a relatively small field of view). I remember that back in the 1990s an independent organisation did some very thorough and professional lens tests on a large number of camera lenses and their highest scoring lens for resolution was a Canon 200mm f/1.8, which beat all the shorter focal length lenses including Leica, Zeiss, Canon, Nikon and many others. The fact that it was 200mm is significant - it did not need to be designed to cover a wide field of view.

Their tests also found that several f/2 lenses by both Leica and Zeiss were higher resolution than all the faster lenses of the same focal length. It's easier to design an f/2 lens of very high resolution if you have to cover the field of field needed for a 50mm (or thereabouts) lens.

The moral is: in general you cannot judge the resolution of a camera lens by the size of its aperture (unless it is diffraction limited and almost no camera lenses are).

bobn2 wrote:

Sunshine7913 wrote:

https://wordpress.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7/

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

Yet I still see sharpness chart for each aperture. That's why I doubt my title. Can anyone tell me about this? If it's true that Leica has the sharpest lens, how come? They are much smaller and I doubt that they can support high mega pixels.

If you spend $7000 on a lens (which is what the Leica f/2 APO Summicron costs) you would expect it to be something special. The reason that it's the sharpest lens in the world is simply that Leica has decided it was going to be, spared no expense in achieving that aim and is happy to pass that cost onto the customer. Why is the lens smaller than the Zeiss and Sigma? Four reasons.

One is that the lens is designed for a shorter lens register (Leica M-mount). This means that a 50mm lens can use a symmetrical design, which naturally cancels out aberrations. 50mm lenses for SLRs can't have a fully symmetric construction. Traditionally they were modified symmetric, but the Otus started a trend for designing them as retrofocal, like a wide angle lens, which makes them larger.

Second, the lens is only an f/2, whilst the others are f/1.4. That means it is intrinsically a more relaxed design.

Third, the high price allows Leica to include ground-to-shape aspheric elements as opposed to the hybrid (plastic aspheric on glass element) or moulded aspheric common in cheaper lenses. This allows a very precisely tailored profile which can ensure better performance.

Fourth, one of the major constraints in lens design is manufacturing tolerance. If you know there will be a dimensional variation in manufacture, then the lens needs to be designed to produce acceptable results over that full range of variance. That compromises the peak performance. If you know that you can manufacture with very tight tolerances, you can design for that peak performance. If you're charging $7000 for a small and simple lens, you can spend the money tightening the tolerances.

In the end, you're getting what you pay for.

I think the last point is the crucial one. That $7000 pays for the rejected elements and the time spent making adjustments.

What you say about short register applies to any mirrorless camera, and there are plenty of not so good lenses for them. It helps but doesn't guarantee quality.

Leica have long been know for sharp lenses, I see it as a case of extreme specialization: great, very expensive lenses... And that's it, the cameras lag far, far behind, there's no autofocus; compare to Canon and their slow progress in cameras, but with an awesome range of lenses, holly cow autofocus and in house developed sensors. One of them leads in market share, the other one is in this tiny niche.

2

D Cox wrote:

bobn2 wrote:

Sunshine7913 wrote:

https://wordpress.lensrentals.com/blog/2014/06/comparing-rangefinder-and-slr-50mm-lenses-version-0-7/

I read the article about the sharpest lens in the world but surprisingly, Leica Summicron 50mm F2 was the sharpest lens in the world which beats both Zeiss Otus and Sigma Art. I have no idea how. I thought both Zeiss and Sigma put a lot of glasses for the highest performance. I can not understand why few Leica lenses with a tiny size have much better IQ than bigger lenses. It seems to defy the physic.

Yet I still see sharpness chart for each aperture. That's why I doubt my title. Can anyone tell me about this? If it's true that Leica has the sharpest lens, how come? They are much smaller and I doubt that they can support high mega pixels.

If you spend $7000 on a lens (which is what the Leica f/2 APO Summicron costs) you would expect it to be something special. The reason that it's the sharpest lens in the world is simply that Leica has decided it was going to be, spared no expense in achieving that aim and is happy to pass that cost onto the customer. Why is the lens smaller than the Zeiss and Sigma? Four reasons.

One is that the lens is designed for a shorter lens register (Leica M-mount). This means that a 50mm lens can use a symmetrical design, which naturally cancels out aberrations. 50mm lenses for SLRs can't have a fully symmetric construction. Traditionally they were modified symmetric, but the Otus started a trend for designing them as retrofocal, like a wide angle lens, which makes them larger.

Second, the lens is only an f/2, whilst the others are f/1.4. That means it is intrinsically a more relaxed design.

Third, the high price allows Leica to include ground-to-shape aspheric elements as opposed to the hybrid (plastic aspheric on glass element) or moulded aspheric common in cheaper lenses. This allows a very precisely tailored profile which can ensure better performance.

Fourth, one of the major constraints in lens design is manufacturing tolerance. If you know there will be a dimensional variation in manufacture, then the lens needs to be designed to produce acceptable results over that full range of variance. That compromises the peak performance. If you know that you can manufacture with very tight tolerances, you can design for that peak performance. If you're charging $7000 for a small and simple lens, you can spend the money tightening the tolerances.

In the end, you're getting what you pay for.

I think the last point is the crucial one. That $7000 pays for the rejected elements and the time spent making adjustments.

I doubt that they reject many elements, they will be individually produced to exact requirements on a CNC machine, as opposed to being batch ground and polished.

What you say about short register applies to any mirrorless camera, and there are plenty of not so good lenses for them. It helps but doesn't guarantee quality.

It doesn't apply to mirrorless cameras so much. For mFT, the register is long compared to 25mm, the required FL for the same AOV, so they can't use a simple symmetric design. I don't thin k there's any priority on ultra performance primes for APS-C mirrorless and for FF mirrorless, most of the lenses available are adapted DSLR designs.

Still, mostly I was addressing why a small simple lens could be made to perform so well, not arguing that those characteristics by themselves guaranteed quality. Put it this way, the complexity of lenses such as the Otus, Art and the new Opera are to do with adopting a retrofocus design, which is used to overcome the requirement for a long register, which isn't a problem for an M mount lens.

Personally, I think the key one is the use of individually ground aspherics. My son is an optical designer, and tells me that such elements can radically simplify lens designs. Hybrid and moulded aspherics are useful, but inevitably widen the tolerances which have to be accommodated elsewhere in the design.

2

photosen wrote:

Leica have long been know for sharp lenses, I see it as a case of extreme specialization: great, very expensive lenses... And that's it, the cameras lag far, far behind, there's no autofocus;

Leica has several camera lines with autofocus, just not the M range.

1

I demand test charts with real pics from indoor and outdoor at the different aperture on both A7iii and A7riii.

So far, I never ever found any IQ test images for Leica lenses so I can not trust verbal proofs.

1

Sunshine7913 wrote:

I demand test charts with real pics from indoor and outdoor at the different aperture on both A7iii and A7riii.

So far, I never ever found any IQ test images for Leica lenses so I can not trust verbal proofs.

The OP was based on Roger Cicala's testing, which is probably more thorough than anything else you'll find on the web.

Besides, the post you replied to was simply making the point that Leica does indeed make AF cameras.

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