Sean Reid has just published an extensive review of SL 50

[IkarusJohn]

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His viewpoint is that of a skilled photographer.   You're assuming a bunch of things to somehow try to dismiss a perfectly reasonable request.

 

 

I don't understand.

 

If you want the digital corrections turned off, you can can't you?  Just use different processing software.  I haven't read Sean's review as I stopped subscribing some time ago.  I agree that there is a philosophical issue for many coming from film and M series cameras because the holy grail is the optically perfect lens.  Some are horrified that the SL50 "reference" lens is not optically perfect, but is a combination of excellent optics and digital correction - as many have pointed out, this gives the designer more options.

 

This is not an Otus lens; it is only used on the SL, so the digital correction is seamless.  The answer to the philosophical problem is answered some pages back - relying on digital correction in processing enabled the designer to avoid some compromises in the optical design, which gives a better end result (apparently) - I assume they are capable of creating an purely optical lens (e.g., the APO Summicron-M 50 ASPH).  Leica presumably chose to do this, with corrections baked into the raw file, as the lens is designed only for the SL (and presumably the TL).  

 

It's a storm in a teacup, isn't it?  You can deal with the distortion of heads at the edge of the frame by using different software - where's the problem?

[jaapv]

The whole argument derives from the confusion between rectilinear distortion, which is addressed in the digital corrections and perspective distortions which affect three-dimensional objects like faces.

[IkarusJohn]

The whole argument derives from the confusion between rectilinear distortion, which is addressed in the digital corrections and perspective distortions which affect three-dimensional objects like faces.

 

 

So what does that mean in practice?  Are you saying that three-dimensional distortion can't be corrected digitally?

[pop]

Perspective distortion is the kind of distortion which has been made notorious by cartographers who were trying to show the globe on a flat map, I believe. Up to now, you could fix it by building a lens which warped the image so that it looked right on paper to humans. You can also correct the seeming distortion digitally.

 

Frequent examples of that kind of distortion are faces or spherical lamps close to the corners of pictures which seem to have disconcerting shapes even if in optical correct projection.

 

Even though it's slightly off topic, I would like to mention in this context the dutch artist M.C.Escher who made several drawings demonstrating extreme cases of perspective distortion.

[IkarusJohn]

Perspective distortion is the kind of distortion which has been made notorious by cartographers who were trying to show the globe on a flat map, I believe. Up to now, you could fix it by building a lens which warped the image so that it looked right on paper to humans. You can also correct the seeming distortion digitally.

 

Frequent examples of that kind of distortion are faces or spherical lamps close to the corners of pictures which seem to have disconcerting shapes even if in optical correct projection.

 

Even though it's slightly off topic, I would like to mention in this context the dutch artist M.C.Escher who made several drawings demonstrating extreme cases of perspective distortion.

 

 

Yes, I understand that, but it doesn't really explain Jaap's post above, where he seems to suggest that perspective distortions cannot be digitally corrected.  I appreciate that distortion of some level needs to be "corrected" just through the process of capturing a 3D image on a flat plane (the sensor); I also understand that perspective (in the true sense of the word) cannot be changed, as the processor cannot adjust something the sensor hasn't captured.

 

But is that the same thing as rounding spheres and faces at the edge of the image?  I'm curious, as I've never really tried this; partly as I am very conscious of not having faces off axis when using wide angle lenses ... 

[Jared]

Sean mentioned in his review, and ultimately I agree, that in the end it's all about the image that is produced.  I don't really care whether Leica incorporates software correction into the process in order to provide the designer more degrees of freedom in other areas.  That's fine.  Heck, I wouldn't really care if it was all accomplished with magic pixie dust.  

 

What I am a little surprised by, though, is that Leica chose to put such heavy emphasis on center field performance wide open that they lost a lot in the corners.  And I doubt it's the interpolation from distortion that is the culprit.  Just look at the MTF charts that Leica publishes.  The center of field performance is outstanding; even wide open the Summilux 50mm SL is on a par with the Summicron M APO at f/2.8!  However, and it's a big however, even at f/5.6 there is enough astigmatism off axis to cause some softening outside the central third of the frame.  Clearly a very different design choice than Leica made with the 50mm APO.  Heck, it's even different from the choices they made with the Nocitlux 0.95 and the Summilux M, both of which manage to keep pretty high MTF values when stopped down slightly across most of the frame.  They only fall apart in the extreme corners.  

 

In any event, based on Sean's samples and what's in the MTF data and what I have seen posted from early adopters, it is an exceptional lens in terms of center resolution, overall contrast, and how it handles out of focus transitions.  My biggest disappointment in what I have seen so far is actually the reviews of the AF performance and the general size and weight of the lens.  I would have expected a bright lens such as a Summilux, coupled with the internal focusing, to be quicker than the 24-90 in terms of AF performance, and it sounds like it's not.  Perhaps Leica will address that in firmware.  Also, while I don't expect 'M'-like compactness from SL lenses, over a kilogram in weight and almost five inches in length seems excessive for a 50mm prime.  Even for a big camera like the SL.

 

- Jared

[JonPB]

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I think it has to do with confusion between linear distortion, where a straight line (e.g., the horizon or architecture) is rendered as a curve, and areal distortion, where a two-dimensional figure (e.g., a circle) is rendered as though it has been stretched (into, in this case, an egg-like shape). Both are distortion. Correcting for one adds more of the other. 

 

So do I. It's only that the request is not reasonable.

 

 

The fact that other developers allow users to disable automatic corrections proves to my satisfaction that this is a perfectly reasonable request. Make it a check box or, better yet, a slider from 0% correction to 100%, as-specified-by-the-manufacturer correction. Default it to 100% and hide it away in some menu, but leave it there for users who know what they want. Is there something I'm missing that makes this unreasonable for Adobe to offer its users?

 

Aren't the arguments against implementing digital corrections for distortion equally applicable to removing the option to adjust exposure or white balance in post? Those are extremely useful features, both when it comes to reproduction accuracy and artistic intent. I understand the arguments on both sides about whether the optics should be corrected, but that isn't what this thread has addressed. I do not understand how discussing the availability of digital editing tools is in any way a criticism of the design that implies or assumes their use.

 

At any rate, the more I know about the 50/1.4, the more eager I am to see those f/2 SL lenses. Interesting stuff from Leica on all fronts.

 

Cheers,

Jon

[zlatkob]

I think it has to do with confusion between linear distortion, where a straight line (e.g., the horizon or architecture) is rendered as a curve, and areal distortion, where a two-dimensional figure (e.g., a circle) is rendered as though it has been stretched (into, in this case, an egg-like shape). Both are distortion. Correcting for one adds more of the other. 

 

 

 

The fact that other developers allow users to disable automatic corrections proves to my satisfaction that this is a perfectly reasonable request. Make it a check box or, better yet, a slider from 0% correction to 100%, as-specified-by-the-manufacturer correction. Default it to 100% and hide it away in some menu, but leave it there for users who know what they want. Is there something I'm missing that makes this unreasonable for Adobe to offer its users?

 

Aren't the arguments against implementing digital corrections for distortion equally applicable to removing the option to adjust exposure or white balance in post? Those are extremely useful features, both when it comes to reproduction accuracy and artistic intent. I understand the arguments on both sides about whether the optics should be corrected, but that isn't what this thread has addressed. I do not understand how discussing tExahe availability of digital editing tools is in any way a criticism of the design that implies or assumes their use.

 

At any rate, the more I know about the 50/1.4, the more eager I am to see those f/2 SL lenses. Interesting stuff from Leica on all fronts.

 

Cheers,

Jon

 

Exactly!  "Correcting for one adds more of the other."  That is the problem.  There are common photographic situations where one type of distortion is desirable, and there are also common photographic situations where the other type of distortion is desirable.  Simple & obvious solution:  have a default, but let the photographer make the final choice, preferably without having to adopt separate software from all of the rest of their workflow. 

[Jared]

Yes, I understand that, but it doesn't really explain Jaap's post above, where he seems to suggest that perspective distortions cannot be digitally corrected.  I appreciate that distortion of some level needs to be "corrected" just through the process of capturing a 3D image on a flat plane (the sensor); I also understand that perspective (in the true sense of the word) cannot be changed, as the processor cannot adjust something the sensor hasn't captured.

 

But is that the same thing as rounding spheres and faces at the edge of the image?  I'm curious, as I've never really tried this; partly as I am very conscious of not having faces off axis when using wide angle lenses ... 

 

Basically, no, you can't correct this digitally.  At least, you wouldn't want to as a default.  The only way to fix it is to give up the idea of a rectilinear lens, at least as you approach the edges.  The effect is, of course, obvious with wide angles because of the perspective.  It's less obvious the longer the focal length.  All rectilinear lenses, though, stretch objects in the corners.  They have to.  Otherwise, straight lines wouldn't appear straight.  You can always introduce some curvilinear distortion after the fact to get faces to look round again.  If you add some barrel distortion the corners will start to show more natural looking shapes in the corners, but then the barrel distortion in the middle of the field can start to exaggerate the perspective, so you need to offset the barrel distortion with some cylindrical distortion. You'll lose your straight lines, but you can theoretically make faces (or any round object) look fairly natural throughout the frame.  

 

Personally, I think what Sean proposed would be optimal--have the distortion correction, vignetting correction, and chromatic aberration correction be applied by default when imported into the software, but be something I could turn off one-by-one if my particular image would benefit from it.  Leica seems to have the habit of wanting to control image quality even if it occasionally impacts my ability to get the shot I want.  Having Lightroom force the application of distortion correction on SL photographs is one example.  Another example is not letting me turn off long exposure noise reduction if I want to.  It makes star trails nearly impossible with an 'M' or an 'SL'.  Even the fact that the 24-90 is as slow as it is, I suspect, is due to not wanting sharpness to drop off below what Leica considers an unacceptable level at larger apertures.  The 'Q' has an odd quirk as well intended to protect the user from taking a lower IQ photograph--stopping down from maximum aperture when focusing close in order to prevent loss of image quality (and I'm not talking bellows effect here--it actually stops down).  I could deal with Leica providing slightly fewer protections from my own incompetence in the interest of giving me a few more tools to work with.  I'd particularly like to see the long exposure noise reduction be optional.  I'd rather make a master dark frame and apply it in post.

 

- Jared

[ramarren]

You're not correct about this.  They do in fact distort people at the edges, more so if digitally corrected.  And the distortion is evident even with a 50mm lens.  The problem is not limited to ultra-wide lenses.  Sean Reid knows his stuff.

 

 

Sigh. I don't care whether "Sean Reid knows his stuff" or not. 

 

I disagree with you, the evidence of my own eyes on my own photographs is enough to convince me that I'm correct. I can see what happens in MY pictures, where I am in full control of the capture and the rendering process. That's enough evidence for me. 

[LD_50]

I don't hear anyone asking for the option to disable ABS braking, power steering and the catalytic converter on their car just so they can get the 'real' driving experience

Take a look at the best "driver's cars" or what those of us who love driving qualify as such and you'll find exactly these types of requests. Power steering is not present in the Alfa 4C for example. ABS is great for controlled braking but non-existent for race cars and wouldn't be present if I was designing a pure driver's car. Catalytic converters come off for any performance application as they offer nothing but emission control.

 

I would prefer LR offer an option to remove corrections but it's not a big deal to me at this point. I would also prefer the cost of a lens be less if the underlying optics are not producing the perceived quality. An automotive example would be I prefer a great sounding and well designed engine in a car with excellent acoustic tuning to engine noise pumped in through the speakers (now present in many cars because the engines just don't actually sound great).

[zlatkob]

Sigh. I don't care whether "Sean Reid knows his stuff" or not. 

 

I disagree with you, the evidence of my own eyes on my own photographs is enough to convince me that I'm correct. I can see what happens in MY pictures, where I am in full control of the capture and the rendering process. That's enough evidence for me. 

 

Photographers have different subjects, different styles, different priorities, so they see different things in pictures.  That's to be expected.  But just consider the possibility that you haven't yet noticed something that others have.  A couple of people in this thread acknowledge the problem and explain it better than I have.  Even if you don't care about what Sean Reid says, other people recognize the exact same problem.

[dgktkr]

...  Leica seems to have the habit of wanting to control image quality even if it occasionally impacts my ability to get the shot I want.  Having Lightroom force the application of distortion correction on SL photographs is one example.  ...

 

 

It's not clear to me why Leica is being blamed for shortcomings in Lightroom. 

 

For people who don't like this about Lightroom, have you tried Iridient Developer? It's very easy to  turn off the DNG imbedded distortion, transverse chromatic aberration and vignetting. Or, instead, you can dial in the amounts you desire.

 

dgktkr

[meerec]

It's not clear to me why Leica is being blamed for shortcomings in Lightroom. 

 

For people who don't like this about Lightroom, have you tried Iridient Developer? It's very easy to  turn off the DNG imbedded distortion, transverse chromatic aberration and vignetting. Or, instead, you can dial in the amounts you desire.

 

dgktkr

Simple and obvious. Leica works with Adobe not with the one-man-show developer of the Iridium thingy. And Leica endorses LR by offering a free licence to use it.

[bernie.lcf]

Simple and obvious. Leica works with Adobe not with the one-man-show developer of the Iridium thingy. And Leica endorses LR by offering a free licence to use it.

 

LR is simply bundled with the product and Leica cooperates with Adobe in a way that everybody else does. This allow Adobe to officially support a camera (which more or less is creating a color profile for it as Leica uses the DNG format).

 

The lens corrections are part of the DNG file and the DNG file was created by Adobe. Leica simply makes use of this feature.

 

Until today, Adobe applies the corrections automatically and does not allow switching it off. This is an Adobe decision, not a Leica decision. In the past, you'd not even know. Today, Lightroom shows a tiny messages that tells you that corrections have been applied.

 

If you want an additional checkbox in Adobe Lightroom, it would be more efficient talking to the makers of Lightroom.

[jaapv]

As I said, the whole discussion centers on  a distortion that is not a lens flaw. It is caused by the rectilinear projection of three-dimensional objects onto a flat two-dimensional plane. This geometrically correct projection does not match the one in our eyes which is onto the curved retina.

So it is the old effect: the camera sees the world precisely, and our eyes and brain do not. That is what postprocessing is for. Leica gives us the perfect rendering by whichever means they can, it is up to us to match that view to our  perception in postprocessing.

The method is very simple: go into lens corrections and introduce some barrel distortion during postprocessing.

 

That is far more effective -as you have control over the amount- and less harmful to the file than disabling the corrections by Leica, as you will throw out any other desirable corrections with the distortion that way.

 

 

About Sean Reid: He is a reviewer I highly respect (and a very nice person as well), but I am convinced that in this case he did not think the implications fully through.

[anickpick]

Sean mentioned in his review, and ultimately I agree, that in the end it's all about the image that is produced.  I don't really care whether Leica incorporates software correction into the process in order to provide the designer more degrees of freedom in other areas.  That's fine.  Heck, I wouldn't really care if it was all accomplished with magic pixie dust.  

 

What I am a little surprised by, though, is that Leica chose to put such heavy emphasis on center field performance wide open that they lost a lot in the corners.  And I doubt it's the interpolation from distortion that is the culprit.  Just look at the MTF charts that Leica publishes.  The center of field performance is outstanding; even wide open the Summilux 50mm SL is on a par with the Summicron M APO at f/2.8!  However, and it's a big however, even at f/5.6 there is enough astigmatism off axis to cause some softening outside the central third of the frame.  Clearly a very different design choice than Leica made with the 50mm APO.  Heck, it's even different from the choices they made with the Nocitlux 0.95 and the Summilux M, both of which manage to keep pretty high MTF values when stopped down slightly across most of the frame.  They only fall apart in the extreme corners.  

 

In any event, based on Sean's samples and what's in the MTF data and what I have seen posted from early adopters, it is an exceptional lens in terms of center resolution, overall contrast, and how it handles out of focus transitions.  My biggest disappointment in what I have seen so far is actually the reviews of the AF performance and the general size and weight of the lens.  I would have expected a bright lens such as a Summilux, coupled with the internal focusing, to be quicker than the 24-90 in terms of AF performance, and it sounds like it's not.  Perhaps Leica will address that in firmware.  Also, while I don't expect 'M'-like compactness from SL lenses, over a kilogram in weight and almost five inches in length seems excessive for a 50mm prime.  Even for a big camera like the SL.

 

- Jared

 

+ 1

[zlatkob]

The method is very simple: go into lens corrections and introduce some barrel distortion during postprocessing.

 

That is far more effective -as you have control over the amount- and less harmful to the file than disabling the corrections by Leica, as you will throw out any other desirable corrections with the distortion that way.

 

That is precisely the wrong method.  You're suggesting photographers apply corrections on top of corrections, thus losing even more of the image they composed and and even more resolution near the image border.  That's like wearing a swimsuit over a tuxedo.  Or wearing red lipstick on top of green lipstick.  These are very sub-optimal methods, making a simple thing more complicated, and giving a worse result.  Not the Leica way, IMO.

[dgktkr]

That is precisely the wrong method.  You're suggesting photographers apply corrections on top of corrections, thus losing even more of the image they composed and and even more resolution near the image border.  That's like wearing a swimsuit over a tuxedo.  Or wearing red lipstick on top of green lipstick.  These are very sub-optimal methods, making a simple thing more complicated, and giving a worse result.  Not the Leica way, IMO.

 

Maybe. Maybe not. It depends on how the software applies the corrections. 

 

One thing Leica has done has been to give us access to the (mostly) raw sensor data and let us choose how we want to process that data by using the software of our choice.

 

dgktkr

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[Chaemono]

Just thought I'd mention that buyers of the 50 SL so far don’t seem to care about the software corrections. There is a waiting list for this lens and my dealer told me he gets them in one piece at a time and for everyone he ships he gets two new orders.