Mauribix Posted July 8, 2008 Share #1 Posted July 8, 2008 Advertisement (gone after registration) Discussing with a friend of mine, we came to a clash of thoughts. He says that Leica has finding more and more problems to make a FF sensor because of the low telecentric "attitude" of the Leica (and RF in general) lenses. He says that while the film has tridimensional properties to capture the inclined raylights coming from the border of the lens, the sensors don't, and this is why Leica had to adopt the inclined microsphere solution to maintain the picture quality in the corners too, otherway, being the sensor a sort of "mirror" it could have reflected the raylight even more producing eventually many bad results. This is why (being the lenses too close to the sensor) he doesn't believe Leica to be easily producing a FF sensor on the M (obviously if the try to make it in the actual state-of-the-art CCD/CMOS way). What do you think? I'm not such an expert to maintein a straight line in my discussion with my friend, so this is why I asking for your opinions/aknowledgement, and please forgive me if I wrote this not in an engineer vocabulary! This open my eyes to a new hypotesis: Could the Foveon be the future for Leica M? Ciao a tutti! Quote Link to post Share on other sites More sharing options...
Advertisement Posted July 8, 2008 Posted July 8, 2008 Hi Mauribix, Take a look here Low telecentric spec.... I'm sure you'll find what you were looking for!
jaapv Posted July 8, 2008 Share #2 Posted July 8, 2008 He is completly right.It is d*mn difficult if not impossible to build a 24x36 sensor for an RF at this point of time for this reason, unless there is something spectacular in the pipeline in Kodak's secret laboratory. The Foveon, alas, is even more sensitive to angle of incidence.. If I were you I'd buy him a nice glass of wine Quote Link to post Share on other sites More sharing options...
Mauribix Posted July 8, 2008 Author Share #3 Posted July 8, 2008 These words I never wanted to hear! I'm gonna buy a nice bottle of Barolo, and my hopes for a FF sensor must be somehow sinking in it... Quote Link to post Share on other sites More sharing options...
hankg Posted July 8, 2008 Share #4 Posted July 8, 2008 Yes, in film the narrow register of RF's is a big IQ advantage in digital it's the opposite. If you could throw out M compatibility you could come up with a full frame DRF that borrowed sensor/electronics directly from a DSLR. Leica is carrying an extra burden maintaining backwards compatibility. Quote Link to post Share on other sites More sharing options...
woodyspedden Posted July 9, 2008 Share #5 Posted July 9, 2008 These words I never wanted to hear!I'm gonna buy a nice bottle of Barolo, and my hopes for a FF sensor must be somehow sinking in it... Ciao Maurizio Please understand that 90% of this functionality and a great bottle of Barolo (now officially to expensive to drink on this side of the pond! LOL) is better than 100% and no wine. Come on, you are Italian and understand this tradeoff better than anyone on the planet. I will even fly to Italia to share the Barolo! Have fun with life Woody (A self proclaimed Hedonist if there ever was one) Quote Link to post Share on other sites More sharing options...
rwfreund Posted July 9, 2008 Share #6 Posted July 9, 2008 I am not too sure. I am using a Phase 1 P45+ back on a horseman with a 35mm lens. There are NO microlenses on the P45+. When I shift to the limit of the 35mm Rodenstock's image circle I can see some pretty strong vignetting, I can also see some color shift across the image caused by the variation in incidence angle. Bottom line, they are all trivially correctable in Capture One. OTOH, in general, raw converters such as ach or lightroom are naive of these artifacts and cannot correct them. If Leica had the same relationship to the raw converter's vendor as the Phace One to Capture One relationship, then these issues seem to be reasonably dealt with with software. To do it in fimware, however, you are stuck with limited time and horsepower, so that aproach limits Leica's options. -bob Quote Link to post Share on other sites More sharing options...
adan Posted July 9, 2008 Share #7 Posted July 9, 2008 Advertisement (gone after registration) If you could throw out M compatibility you could come up with a full frame DRF that borrowed sensor/electronics directly from a DSLR. Yep. Only trouble is that the lenses (at least) would tend towards SLR size, as well. And an extremely compact SLR lens (Olympus or Pentax from the film era) takes a 49mm filter, whereas M lenses routinely can fit a 39mm. Compare also the lengths of the C/V 15mm with the WATE (designed to maximize digital friendliness). Going to "SLR" lens designs for RF use will kill a lot of the M's selling power, just based on size and ignoring the compatability-with-film-Ms issue. I don't care especially if new lens designs from Leica work with film cameras - I definitely DON'T want them to be the size of honking great 17-35 or 24-70 SLR lenses. Leica's approach, I think, will continue to be to design new compact M lenses, especially new wide-angles, for the compact (18mm x 27mm) format. We'll see what Photokina reveals. Quote Link to post Share on other sites More sharing options...
Shootist Posted July 9, 2008 Share #8 Posted July 9, 2008 Adan I think you have hit the nail directly on the head. Leica needs to introduce some fast very wide lenses, 12 +/- to 21 (or 18), designed specifically for the smaller sensor in the M8. Even IF they plan on someday putting a 36x24 sensor in a digital M. Not that the CV lenses are bad but they are very slow. A 12 or 14 or 16 f/2.8 would be a top seller. Quote Link to post Share on other sites More sharing options...
Kittyphoto Posted July 9, 2008 Share #9 Posted July 9, 2008 I used to have Lightphase from Phaseone which has 35mm CCD size with Horseman Digiflex wich Nikon 35mm lens. No micro lens no vignette. But the distance from lens to back is much longer than leica lens. I agree with the idea that it is very difficult for leica to do FF. I notice that Hologon 16 mm which has very thin gap from lens to CCD show a lot of vignette and color magenta cast at the corner on M8 not on film. Quote Link to post Share on other sites More sharing options...
lxlim Posted July 9, 2008 Share #10 Posted July 9, 2008 Yes to that. Small and fast, designed for the 1.3x sensor. It would mean more sales for Leica. And hopefully a 24~50 f3.5. Tried out my M8 in an event coverage job with the WATE and the leica flash in auto mode. Its a blast! But I had to do a lot of cropping due to the extra wide FOV which I could not judge as I am not quite used to the WATE without the finder. Quote Link to post Share on other sites More sharing options...
marknorton Posted July 9, 2008 Share #11 Posted July 9, 2008 How any new wide-angle lenses look will tell us about the realities of FF. If they follow the WATE trend (if you can have a trend with just one example), it may be Leica softening us up to say "FF is coming, but not for the optical troublemakers like the 21 and 24mm Elmarits (cropped only)". If they don't, I think Leica are telling us FF doesn't make sense or can't be done. Quote Link to post Share on other sites More sharing options...
AlanG Posted July 9, 2008 Share #12 Posted July 9, 2008 For some time, I've wondered about this full frame "issue" with rangefinder lenses. First of all it is not a problem with lenses of 50mm and up as the design of these lenses can be the same on a rangefinder as on an slr. Maybe the 35mm lenses would be ok on a full frame sensor too. As for the shorter lenses, that will depend on the lens design and the sensor. Could it be that some of Leica's wide lenses would work quite well on a Canon or Nikon full frame sensor? (We'd know if it were possible to try the lenses on those cameras.) Well someone could try the CV 15 on the Nikon FF DSLR (mirror up) because it is available in that mount. And the guy at the 16/9 web site got good results with this lens on a 5D. As rwfreund said, this doesn't seem to be a big issue with MF sensors and they often employ lenses that are much closer to the sensor and have a much wider field of view than the Leica wides have on the M8. (The 24mm Digitar's rear element is pretty close to the sensor and it projects a circle that covers 36x48mm.) Plus lenses are often shifted or tilted on MF thus increasing the angle of light hitting the sensor. The Nikon and Canon 24 tilt shift lenses probably end up projecting the light at more of an angle too. And there is no color shift on the Canon FF when using this lens. (I can't speak for the Nikon.) In the old days wide angle lenses for rangefinders were of a traditional design. But now they are retrofocus and not much different from the design of SLR lenses. I am posting three illustrations to make the point. One shows the diagram of a 24 2.8 Elmarit with the diagram of a 24 2.8 Canon EF overlayed on it. (Not necessarily to scale.) Another shows some basic Schneider lens diagrams - traditional wide angle, retrofocus wide angle, and standard symmetrical. The last one shows the size of a 24mm f 5.6 Digitar lens. It takes 52mm filters so that is a reference point for its size. It is on an Alpa lensboard with a compact focusing mount. The Digitar clearly is not telecentric. Food for thought... Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/57311-low-telecentric-spec/?do=findComment&comment=599838'>More sharing options...
Mauribix Posted July 9, 2008 Author Share #13 Posted July 9, 2008 ...I will even fly to Italia to share the Barolo! Have fun with life Woody (A self proclaimed Hedonist if there ever was one) The day you decide to fly, just give me a call. I'll prepare the glasses! P.S. I live in the land of wines (Piemonte), it's not that difficult to share some barolo, nebbiolo or barbera! Quote Link to post Share on other sites More sharing options...
ChrisC Posted July 9, 2008 Share #14 Posted July 9, 2008 ...The last one shows the size of a 24mm f 5.6 Digitar lens.... The Digitar clearly is not telecentric.....Food for thought... Alan - It's curious how so many people want the advantages of rangefinder lens design, coupled with the advantages of film's light gathering, with absolute demands for ultra fast optics; it is a circle which is reluctant to be squared. I sometimes wonder if I'm the only one here who would like a lens which denied known problems of lens design but in another direction. I'd love a lens which got sharper as I stopped down past M8, but I'm not daft enough to wait for one. I too come from a background of using Sneider f5.6 Super Angulons, and Rodenstock Apo Grandagon lenses, losing another two stops by putting a centre filter on the front. and then stopping the lens down substantially. Introducing the experience of larger-format digital photographers into this discussion does raise 'food for thought'. I was wondering if the 24mm Digitar for example, actually has, effectively, a centre-filter built into it's design? ................ Chris Quote Link to post Share on other sites More sharing options...
hankg Posted July 9, 2008 Share #15 Posted July 9, 2008 Lens size is one of the factors that designers must prioritize. Look at the current 35mm ASPH Summicron compared to the tiny previous version. If you make size a design priority even autofocus DSLR primes can be small look at the Pentax DA limiteds. 40/2.8 Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! 70/2.4 Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! 70/2.4 ' data-webShareUrl='https://www.l-camera-forum.com/topic/57311-low-telecentric-spec/?do=findComment&comment=600099'>More sharing options...
AlanG Posted July 9, 2008 Share #16 Posted July 9, 2008 ... I was wondering if the 24mm Digitar for example, actually has, effectively, a centre-filter built into it's design? ................ Chris They still require a center filter to produce more even illumination. So you'll shoot at the equivalent to f11- f16 at most. My whole point of bringing up this lens is that it sends the light to the sensor at an angle that is much steeper than that of any of the Leica lenses. I think that Canon (and probably Nikon) have sensors that show less color shift than some other sensors when a lens is shifted. And now Sinar is saying that Rodenstock will be releasing a 23mm lens that projects a 70mm circle thus allowing for some movements for this wide lens on an MF sensor. When used with a 36x48mm back that is the equivalent to an 16.5mm tilt/shift lens on a full frame DSLR. (60mm diagonal length on this sensor.) The 24mm Digital does not allow for any movement on this format. Once I tested the Kodak SLRc with a Canon 24 TSE lens. It produced extreme color shifting when the lens was shifted. I've never seen any color shifting when using this lens on a Canon. So maybe the Fill Factory sensor and micro lenses in the Kodak camera were at fault that would be similar to the situation with the M8. Quote Link to post Share on other sites More sharing options...
ChrisC Posted July 9, 2008 Share #17 Posted July 9, 2008 They still require a center filter to produce more even illumination........ Rodenstock will be releasing a 23mm lens...... the equivalent to an 16.5mm tilt/shift lens on a full frame DSLR...... Thank you for the clarification. and the additional information. ............. Chris Quote Link to post Share on other sites More sharing options...
adan Posted July 9, 2008 Share #18 Posted July 9, 2008 Alan, there is something misleading in your Leica/Canon diagram overlay. The Canon lens should be shifted significantly to the left to account for the extra depth of an SLR mirror box. The "backfocus" of a lens is just a big a part of a lens design as the positions of the glass elements themselves. And the longer backfocus of SLR lenses in itself has a "telecentric" effect, making the light rays more perpendicular to the image surface for a given image/sensor size. That being said, yes, Leica's wides since the 1970's have been slightly retrofocus in design to allow space for metering, either the "arm" of the M5/CL or the FOV of the M6-7-8 meter cell. Nowhere near as RF as an SLR 14 or 20 or 24 (WATE excepted) - but a little. Said another way - yes, a Canon 24mm, via a 5/8" adapter, could be fitted on a Leica M body, and if the M body had a full-frame sensor, the Canon lens would perform generally as well on that sensor as it does on a 1Ds/5D. A Leica 24 R lens would do the same, as would a huge Leica "M" lens redesigned along SLR-lens lines, with the same extralong backfocus from GLASS to sensor.. That proves absolutely zip about how the current, small Leica 21/24/28 lenses would perform on the same sensor. Quote Link to post Share on other sites More sharing options...
jaapv Posted July 9, 2008 Share #19 Posted July 9, 2008 The retrofocus design has another reason as well. Now that the calculations facilitated by the use of computers, the retrofocus design offers more scope for corrections. Quote Link to post Share on other sites More sharing options...
AlanG Posted July 9, 2008 Share #20 Posted July 9, 2008 Alan, there is something misleading in your Leica/Canon diagram overlay. The Canon lens should be shifted significantly to the left to account for the extra depth of an SLR mirror box... I simply overlayed them to show that Leica is using a typical retrofocus design. Everyone knows that the flange to sensor distance is different between the two. They are not necessarily even the same scale in relationship to each other. The point of my posting had nothing to do with using the Canon lens on the M8 or thinking that Leica should redesign any lenses. I am speculating that with the right full frame chip, the current Leica designs would work ok. How else can we explain the excellent performance of a 24mm APO Digitar on a 36x48mm sensor? Here is a cross section of the Digitar. It is not a retrofocus lens and must be used very close to the sensor. (Only a few cameras will work with it.) The 24mm Digitar has a 100 degree field of view that just covers the 36x48mm format. So the angle of the light hitting the corners is very steep. This the complete opposite of a telecentic design. So if a non retrofocus 24mm Digitar works on a 36x48mm sensor, should the retrofocus 24mm Elmarit work well if it only has to cover 24x36mm of that same sensor? Welcome, dear visitor! As registered member you'd see an image here… Simply register for free here – We are always happy to welcome new members! Quote Link to post Share on other sites Simply register for free here – We are always happy to welcome new members! ' data-webShareUrl='https://www.l-camera-forum.com/topic/57311-low-telecentric-spec/?do=findComment&comment=600606'>More sharing options...
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