colonel Posted September 8, 2015 Share #101 Posted September 8, 2015 Advertisement (gone after registration) A lens is not made "for film" or "for digital" That is an urban myth. (Or as we call it in Dutch a Monkey Sandwich story) My parents are from South Africa and talk about animals all the time. My favourite is Jakkals trou met wolf se vrou Link to post Share on other sites More sharing options...
Advertisement Posted September 8, 2015 Posted September 8, 2015 Hi colonel, Take a look here Leica's organic rendering versus plasticized Sony 7RII. I'm sure you'll find what you were looking for!
pgk Posted September 8, 2015 Share #102 Posted September 8, 2015 A lens is not made "for film" or "for digital" That is an urban myth. (Or as we call it in Dutch a Monkey Sandwich story) Lenses are actually designed with specific parameters in mind. Some older lenses were obviously not designed for use with digital sensors and whilst they were ok on film they are not good on digital - the 21/3.4 Super-Angulon-M and Canon 20mm f/2.8 are good examples - the first performs well in resolution terms but suffers from coloration in the corners on digital, the second performs poorly on digital (even 10MPixel) in that it has very soft corners. Of course it could be argued that the Super-angluon is of a very old design and that its rear principle point is too close to the sensor plane for use on a digital sensor, but isn't this the point. And the Canon 20mm /2.8 really never was a stellar performer - again it could be argued that what was just about 'acceptable' on film is highly stressed on high MPixel sensors - the design requirements of the lens may have been met originally, but have now moved - I can't figure out why Canon have not updated this focal length. Whilst not entirely pertinent this link might be of interest: http://blogs.zeiss.com/photo/en/wp-content/uploads/sites/4/2011/12/en_CLB41_Nasse_LensNames_Distagon.pdf Link to post Share on other sites More sharing options...
jaapv Posted September 8, 2015 Share #103 Posted September 8, 2015 Still, that does not make them "designed for film". More modern systems may show up flaws, modern lenses may be more telecentric to reduce incidence angles, but they will work as well on film as on a sensor. If they were designed "for digital" their performance on film would suffer. Link to post Share on other sites More sharing options...
CheshireCat Posted September 8, 2015 Share #104 Posted September 8, 2015 A lens is not made "for film" or "for digital" That is an urban myth. (Or as we call it in Dutch a Monkey Sandwich story) Unfortunately, this is not a myth. The M system was originally designed for film. I think we all agree on this. Back then, Leica lens designers ignored the thickness of sensor optical layers because... well, there was no sensor but film The problem with digital sensors is that they suffer from aliasing (moire) and are very sensible to light frequencies outside of the visible spectrum. For this reasons, sensor manufacturers add optical layers to their sensors, such as AA filter and light frequency cutoff. The problem with these optical layers is that they have a thickness, hence they are actually part of the optical system. This is a big issue with some M lens designs, as the aberrations introduced by these layers depend on the angle at which the light rays hit the sensor. Unlike reflex wides (retrofocus designs), light through most M wides hits the sensor at very steep angles, especially in the corners of the frame. I think this is the reason why for years Leica said "it is impossible to have a digital M". Indeed, it does not make much sense to switch a system to digital if many lenses could not be used. But after a long time, Leica finally realized it was feasible to use a custom sensor minimizing the thickness of these optical layers. In a certain sense, emulating film. Also, the sensor would be a smaller format than film, therefore not using the periphery of the full-frame image, where the "bad aberrations" were really bad. The M8 was born, and indeed it worked with Leica lenses, with a few caveats. Removing the AA filter was more a feature than an issue ! Moire was a problem in some images, but users loved the sharpness of the images. However, removing (or reducing) the thickness of the IR was a big problem causing IR contamination. Users were recommended to use IR filters on the lenses. The M9 extended the custom sensor format to full-frame and improved the IR filter. Still it had some IR contamination, due to the reduced thickness of the cutoff filter. And sensor peeling problems. The last incarnation is the M240. Technology advanced, but still it has some IR contamination problems, and requires color vignetting to be corrected in post. Other manufacturers (like Sony) don't need to support a lens system born in the film era. So they use digital sensors with all required optical layers, and design lenses to minimize the issues of digital sensors. That is: lenses designed for digital. Link to post Share on other sites More sharing options...
algrove Posted September 8, 2015 Share #105 Posted September 8, 2015 Resolution comparo part 1. Raw files developed in C1 v8, linear response, default settings. Exposure, contrast and WB (more or less) equalized in PS3. Leica file upsized to 42MB (bicubic in CS3). 100% crops. Sony crop above. Crop_01.jpg The Leica image is just plain "earlier in time". Link to post Share on other sites More sharing options...
CheshireCat Posted September 8, 2015 Share #106 Posted September 8, 2015 The Leica image is just plain "earlier in time". That is because Leica is always late Link to post Share on other sites More sharing options...
colonel Posted September 8, 2015 Share #107 Posted September 8, 2015 Advertisement (gone after registration) But both the Canon EF mount and Nikon F mount were designed for film. I can't see how that's relevant Link to post Share on other sites More sharing options...
pgk Posted September 8, 2015 Share #108 Posted September 8, 2015 Still, that does not make them "designed for film". More modern systems may show up flaws, modern lenses may be more telecentric to reduce incidence angles, but they will work as well on film as on a sensor. If they were designed "for digital" their performance on film would suffer. What I was trying to get at is that the design parameters have changed. Current requirements of a lens design are more demanding generally and older designs had less 'stress' placed upon them when used on film, so older designs were designed for the requirements of film and as such were 'designed for film' although at the time they would have been 'designed for photography'. I suspect that if a designer was asked to design a lens today for say, 35mm film use, then the design parameters would be different to those for a lens designed for a 50MPixel FF sensor. Additionally, as has been debated on the forum at length in other threads, knowing the exact characteristics of a lens design and utilising information about its in use parameters (aperture, focus distance, etc) can help software adjustments and increase its apparent performance in various ways. So its not just about the optics. If you wanted to argue the point you could quite legitimately IMO say that Leica M lenses which have always been 6-bit coded are fully digital designs, earlier but 6-bit codable lenses are legacy lenses capable of meeting the demands of digital cameras and lenses which cannot be coded are film designed lenses not capable of the levels of performance required by digital cameras (in terms of colour evenness). Can I just add that lens flange diameters and flange to image plane distances impose significant design restrictions, so problems evident on a Leica M lens with its small diameter flange and short flange to image plane distances will be more evident than those from a 'legacy lens' from a film SLR which has larger diameter and distance. Link to post Share on other sites More sharing options...
uhoh7 Posted September 8, 2015 Share #109 Posted September 8, 2015 A lens is not made "for film" or "for digital" That is an urban myth. (Or as we call it in Dutch a Monkey Sandwich story) This, I'm afraid, shows you do not understand the whole issue of sensor cover glass and how it can effect lens performance, even when much thinner than the Sonys. Why on earth do you think lenses like the CV 21/4 are so much better on film? Film in effect, has "no cover glass". The closer a digital sensor can get to this, the better, for any lens which has been originally made for film. Especially for WA and UWA, and particular designs, where the rays have extreme angles on the edges. Link to post Share on other sites More sharing options...
CheshireCat Posted September 8, 2015 Share #110 Posted September 8, 2015 But both the Canon EF mount and Nikon F mount were designed for film. I can't see how that's relevant Wide angles for reflex cameras are retrofocus designs, which are basically "inverted tele" lenses. This prevented lens designs with extreme angle of incidence. Link to post Share on other sites More sharing options...
jaapv Posted September 8, 2015 Share #111 Posted September 8, 2015 This, I'm afraid, shows you do not understand the whole issue of sensor cover glass and how it can effect lens performance, even when much thinner than the Sonys. Why on earth do you think lenses like the CV 21/4 are so much better on film? Film in effect, has "no cover glass". The closer a digital sensor can get to this, the better, for any lens which has been originally made for film. Especially for WA and UWA, and particular designs, where the rays have extreme angles on the edges. I think you have hold of the wrong end. The reason you think such lenses are "better" is because you don't see the flaws on film, it being more forgiving. It has nothing to do with being "designed for film" (whatever that may be. What aberration should a lens designer build in to make a lens perform better on film?) Of course the incidence angle has to do with it, that is about all. It is indeed more challenging for a sensor to accept steep angles, we all know that, and the reasons. Of course Leica will design their lenses to perform equally well on film and sensor. It is time this "designed for" nonsense was put to bed. Come to think of it, if there were any basis for this myth, Leica would have brought out two versions of the Apo-Summicron, one for film, one for digital... Link to post Share on other sites More sharing options...
lct Posted September 8, 2015 Share #112 Posted September 8, 2015 Are you sure you're not playing with words? A lens designed for digital (50/2 apo) is designed for film as well whilst a lens designed for film ( CV 15/4.5) is not designed for digital by definition. Reason why we have now a new CV 15/4.5 designed for digital. But of course it will work on film as well. Link to post Share on other sites More sharing options...
asiafish Posted September 8, 2015 Share #113 Posted September 8, 2015 A major factor in the Sony success with the E mount has been it's ability to shoot other makers lenses. When the A7 was released, with few lenses, this was touted by Sony and their reps. "Don't worry you can put other lenses on there" Which would have been fine with a thin cover glass. Instead they had totally broken with the norm for FF and put a very thick one in place, which to this day is problematic for many reasons. I'm still miffed at Sony's cynical hype and misleading claims in 2013. I certainly was taken in. Basically the Sony "talkers" had no connection with the design team at all, before or after the camera was built. It's too bad because it would be so easy to please many current and potential customers with a specific version for this application: use of film lenses in general. They already have many versions of the camera, and they cannot make enough 25/2s as it is. Even the abilty to recognize and correct M lenses is a simple affair which could be accommodated in firmware on such a A7 version. The thick cover glass only seems to be a problem with rangefinder lenses. Old SLR lenses work beautifully on the Sony cameras. Link to post Share on other sites More sharing options...
pgk Posted September 8, 2015 Share #114 Posted September 8, 2015 What aberration should a lens designer build in to make a lens perform better on film? If you are designing for digital then resolution might be gained at the expense of say distortion which can be corrected by software (as we all know from other Leica cameras ). Designing for film meant good resolution over the whole frame AND low distortion - so designs like the Super-Angulon were very acceptable, although excellent central resolution, reasonable edge resolution and low distortion came at the price of vignetting and a steep incidence angle, the latter of which gives digital problems. (The protruding rear section of the lens was also problematic with metered cameras and resulted in a new design aimed at solving this problem - the design parameters had changed). Lenses like the 43-86 Nikkor resolved well for an early zoom but distorted terribly (you can see barrel at one end and pincushion at the other on 6" x 4" prints). The problem is that lenses were, in the past, designed for 'photography' but now the design parameters required for 'photography' are often not up to high MPixel sensors requirements because 'photography' meant 'film'. I have friends who are lens designers and they tell me that lens design is about knowing what your lens is required to do and it is then designed to meet those requirements. The requirements for film were/are different from those of digital so the parameters used will vary. Leica M lenses are a special case because they transfer nothing from lens to camera electronically - only the 6-bit code is read by the camera. So many of the software required correction parameters are unavailable. Add this to specific design parameters of specific camera modes are their performance will drop relative to purpose designed lenses for those models. There is nothing overly complex about this and to me its amazing how well some of the M lenses work when asked to do so in ways that their designers never dreamt of. But many older lenses were 'designed for film' and in my book there is no getting away from this. Link to post Share on other sites More sharing options...
pgk Posted September 8, 2015 Share #115 Posted September 8, 2015 The thick cover glass only seems to be a problem with rangefinder lenses. Old SLR lenses work beautifully on the Sony cameras. See the last paragraph of my post 108. Link to post Share on other sites More sharing options...
jaapv Posted September 8, 2015 Share #116 Posted September 8, 2015 If you are designing for digital then resolution might be gained at the expense of say distortion which can be corrected by software (as we all know from other Leica cameras ). Designing for film meant good resolution over the whole frame AND low distortion - so designs like the Super-Angulon were very acceptable, although excellent central resolution, reasonable edge resolution and low distortion came at the price of vignetting and a steep incidence angle, the latter of which gives digital problems. (The protruding rear section of the lens was also problematic with metered cameras and resulted in a new design aimed at solving this problem - the design parameters had changed). Lenses like the 43-86 Nikkor resolved well for an early zoom but distorted terribly (you can see barrel at one end and pincushion at the other on 6" x 4" prints). The problem is that lenses were, in the past, designed for 'photography' but now the design parameters required for 'photography' are often not up to high MPixel sensors requirements because 'photography' meant 'film'. I have friends who are lens designers and they tell me that lens design is about knowing what your lens is required to do and it is then designed to meet those requirements. The requirements for film were/are different from those of digital so the parameters used will vary. Leica M lenses are a special case because they transfer nothing from lens to camera electronically - only the 6-bit code is read by the camera. So many of the software required correction parameters are unavailable. Add this to specific design parameters of specific camera modes are their performance will drop relative to purpose designed lenses for those models. There is nothing overly complex about this and to me its amazing how well some of the M lenses work when asked to do so in ways that their designers never dreamt of. But many older lenses were 'designed for film' and in my book there is no getting away from this. That only means that designers cannot take technology into account that does not exist. Rather obvious.I think it would better to mention that some sensors are intended to work with older lens designs. Actually the Nikkor you mention appears to be designed for digital, as the distortion is easily corrected in postprocessing. Many early zooms perform a lot better on a digital camera than they ever did on film, aided by CA removal and distortion correction. Link to post Share on other sites More sharing options...
CheshireCat Posted September 8, 2015 Share #117 Posted September 8, 2015 Let me fix that for you: Of course Leica will design their lenses to perform equally well on film and their very special sensor that struggles to emulate film. ... nice try, though Link to post Share on other sites More sharing options...
jaapv Posted September 8, 2015 Share #118 Posted September 8, 2015 It is indeed a bit of an uphill struggle, but not too bad I think , especially with the current range. Link to post Share on other sites More sharing options...
edwardkaraa Posted September 8, 2015 Share #119 Posted September 8, 2015 It has been demonstrated, for instance by lensrentals optical bench tests, that a lens designed for the thick sensor glass of the A7 performs slightly worse without the glass, while lenses designed for film will perform noticeably worse with the thick cover glass. That is probably because the digital lenses have less severe angles of incidence which improve performance on digital but do not affect film. On the other hand, digital lenses are designed with a negative astigmatism in the corners to counteract positive astigmatism caused by the sensor glass. This inevitably affects performance on film or sensors with thinner glass. Link to post Share on other sites More sharing options...
pgk Posted September 8, 2015 Share #120 Posted September 8, 2015 That only means that designers cannot take technology into account that does not exist. How true. But so is the converse. Lens designers can take into account specifics of sophisticated camera designs such as thickness of cover glass or focus distance and aperture specific aberrations. Provided that is, that such data is available otherwise all adjustment has to be done manually bey eye/experience. What I'm trying to get across is that in the past designs were based on different, less data rich technologies and as such were based on the idea of film being the image recording medium. The lens design requirements were different because technologies were different. So many film designed lenses were not optimised for specific digital systems because they were designed for film. Link to post Share on other sites More sharing options...
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