adan Posted January 1, 2012 Share #1  Posted January 1, 2012 Advertisement (gone after registration) SLR Magic announces HyperPrime CINE 50mm T0.95 M-mount lens: Digital Photography Review  Interesting that this lens, calibrated in cine T-stops....  > despite the company name, won't work on video-SLRs except for macro (uses short-backfocus Leica M mount)  > goes to the trouble of including Leica RF coupling (push-rod focus cam visible in the rear view, and the mount has the cutout for RF roller movement.)  (Clarification - may be available directly in Sony E-mount (Nex). Not sure if Noktor is the same company as SLRMagic)  > does not use aspheric elements (unless that is a typo - "built with modern non aspherical lens technology")  > is scheduled for relase at photokina - right alongside the (hypothetical) Leica EVIL and (hypothetical) Leica M10 with (hypothetical) CMOS sensor and (hypothetical) live-view/video capability.  If a lens has a T-stop of f/0.95, does that imply it is faster in terms of regular f/stops, and if so, how much? f/0.8? Link to post Share on other sites More sharing options...
Advertisement Posted January 1, 2012 Posted January 1, 2012 Hi adan, Take a look here Noctilux T/0.95 competitor...... I'm sure you'll find what you were looking for!
Ellie Posted January 1, 2012 Share #2  Posted January 1, 2012 The sample picture looks close to the Noctilux, perhaps even softer in the background SLR Magic HyperPrime 50mm f/0.95 lens with Leica M mount announced | Leica News & Rumors  Link to post Share on other sites More sharing options...
yanidel Posted January 1, 2012 Share #3 Â Posted January 1, 2012 975 grams ... game over. Link to post Share on other sites More sharing options...
wattsy Posted January 1, 2012 Share #4 Â Posted January 1, 2012 0.7m close focus distance ... game over. Link to post Share on other sites More sharing options...
TomB_tx Posted January 1, 2012 Share #5 Â Posted January 1, 2012 Not sure if Noktor is the same company as SLRMagic) I believe SLRMagic bought Noktor Link to post Share on other sites More sharing options...
perb Posted January 1, 2012 Share #6 Â Posted January 1, 2012 If a lens has a T-stop of f/0.95, does that imply it is faster in terms of regular f/stops, and if so, how much? f/0.8? Â According to F-number - Wikipedia, the free encyclopedia "A real lens set to a particular T-stop will, by definition, transmit the same amount of light as an ideal lens with 100% transmission at the corresponding f-stop". Â Unless the f-number is available, to find the f-number of a particular T0.95 lens you need to know its transmission factor. I very rarely see transmissions published, so either a measurement is needed, or a crude estimate based on typical values could be made. Â Suppose for example that the transmission factor is 0.95 (I haven't the faintest how close to reality this is). Then we need to open up with a factor of 1/0.95 which is about 0.15 stops, which is spot on your suggestion of f/0.8 Â Regards Per Link to post Share on other sites More sharing options...
Ellie Posted January 1, 2012 Share #7 Â Posted January 1, 2012 Advertisement (gone after registration) I just saw these videos, night World Premiere !!! SLR Magic HyperPrime CINE T0.95 / 50mm Part I : The Night Tests on Vimeo and day World Premiere !!! SLR Magic HyperPrime CINE T0.95 / 50mm Part II : The Day Tests on Vimeo Link to post Share on other sites More sharing options...
perb Posted January 1, 2012 Share #8  Posted January 1, 2012 Thanks for the links Ellie  The vimeo pages claim f0.92 which should correspond to a transmission of ca 0.99.  A rather academic difference if true  Regards Per Link to post Share on other sites More sharing options...
StephenPatterson Posted January 1, 2012 Share #9 Â Posted January 1, 2012 September is a long way off... Link to post Share on other sites More sharing options...
pico Posted January 1, 2012 Share #10 Â Posted January 1, 2012 T-Stops are generally slower than F-Stops, especially with complex lenses, and certainly with zooms (although we are not concerned with zooms here) - except when a fixed-focal lens is focused closely the F-Stop changes because the focal length changes - even if a bit. I'd guess the lens in question is an F/1 or F/1.2. Â This lens looks like a desperate attempt to push a cine lens into still photography. You cannot translate T-Stops directly to F-Stops for all lenses with a simple chart of equivalents because T-Stops are all dependent upon a particular lens. Perhaps they will publish such a chart for this lens. Maybe it won't matter with camera w/o F-Stop communication - like the M. Link to post Share on other sites More sharing options...
gyoung Posted January 1, 2012 Share #11 Â Posted January 1, 2012 I don't see how a T stop can ever be faster than an F stop, they are used and are important on complex lenses where the light transmission is less than the area of the F stop would indicate. The only one I have ever used was an Angenieux 12-120 zoom on an Ariflex. Â Early zooms of such high zoom ratio were notoriously bad at transmission, there was so much glass they didn't need UV filters either, the light 'trickled through in a dirty brown stream' to quote a long ago review of a rather poor zoom. Â Gerry Link to post Share on other sites More sharing options...
ho_co Posted January 2, 2012 Share #12 Â Posted January 2, 2012 If you look at the mechanical design of the Leica Cine Summiluxes, it seems obvious that SLR Magic hasn't designed the lens as a cinema lens, but as a still lens. Â I don't understand the confusion over T-stop vs f-stop. F-stop is a measured mechanical value derived from focal length and clear aperture. T-stop is actual measured light transmission. If you have a lens calibrated in T-stops, you don't care about the actual aperture. Â For still photography the two are normally so close as makes no nevermind. It's when you're trying to match exposure exactly in camera with different lenses that the T-stop becomes important. Â That's my understanding, at any rate. Link to post Share on other sites More sharing options...
gyoung Posted January 2, 2012 Share #13  Posted January 2, 2012 Yes indeed, mine too  Gerry Link to post Share on other sites More sharing options...
jaapv Posted January 2, 2012 Share #14  Posted January 2, 2012 I don't see how a T stop can ever be faster than an F stop, they are used and are important on complex lenses where the light transmission is less than the area of the F stop would indicate. The only one I have ever used was an Angenieux 12-120 zoom on an Ariflex. Early zooms of such high zoom ratio were notoriously bad at transmission, there was so much glass they didn't need UV filters either, the light 'trickled through in a dirty brown stream' to quote a long ago review of a rather poor zoom.  Gerry  Actually exposure meters are calibrated for a small loss in light through the lens. That means that lenses that have less transmission loss than average need to be exposed for a fastet T stop in critical exposure. An example is the Telyt 400 6,8 which needs to be exposted for a half-stop faster. Of course TTL measuring avoids the whole thing. Link to post Share on other sites More sharing options...
01af Posted January 2, 2012 Share #15  Posted January 2, 2012 Actually exposure meters are calibrated for a small loss in light through the lens. That means that lenses that have less transmission loss than average ... Please! "Average transmission loss" ... how much would that be, in your opinion? Don't be silly!  A typical modern multi-coated lens with five or six elements has a transmission of approx. 98 %. That's a loss of 0.06 f-stops, or 1/17th of an f-stop. Do you really believe that light meters are (or can be) calibrated to this kind of accuracy?  The whole concept of T-stops is to allow for perfect accuracy of exposure with lenses that have significantly higher transmission losses than 2 or 3 %. Lenses for movie or TV cameras often have 30 or 40 elements or more; their transmission losses can go far beyond 10 % ... even beyond 50 % in extreme cases. How, do you think, is a light meter calibrated for some arbitrary "average transmission loss" going to help? Do you think T-stops are taking an obscure "average transmission loss" into consideration?  Regarding the upcoming SLR Magic Hyperprime Cine 50 mm T/0.95 lens ... this lens is neither going to be a cine lens nor is it going to be T/0.95. Both 'cine' and 'T' are nothing but empty marketing yackety-yak. The focus throw is way too short for a cine lens (heck, it's too short for anything), and if the lens really was any faster than f/0.95 (which it would be when it really was a true T/0.95) then it would be a noteworthy world's first for a general-purpose photography lens—nothing would keep them from yelling out loud. Instead, they just pretend it was T/0.95 rather than f/0.95 (not necessarily cheating but exploiting tolerances to the limit of what industrial standards allow) because that's what is required to keep up the 'cine' guise. Link to post Share on other sites More sharing options...
gyoung Posted January 2, 2012 Share #16 Â Posted January 2, 2012 Actually exposure meters are calibrated for a small loss in light through the lens. That means that lenses that have less transmission loss than average need to be exposed for a fastet T stop in critical exposure. An example is the Telyt 400 6,8 which needs to be exposted for a half-stop faster. Of course TTL measuring avoids the whole thing. Â IMHO thats tosh, I have just been out checking over the Weston I bought just before Christmas, comparing it with the M6ttl, Voigtlander VCII on the M3 and with an FM2. Therre are subtle differences in readings between all of them, as expected from 50 years of experience. Isn't the 400/6.8 a very simple optical formula? Light losses through inefficiency should be minimal and lost by far in the difficulties of metering for such a narrow angle of view. Â I doubt its possible to calibrate a light measuring device that accurately, and I have used ones in the past which measure in Lumens etc for architectural lighting spec stuff, and we have to develop a technique to get accurate exposures with a particular meter, thats all part of the fun! Â Gerry Link to post Share on other sites More sharing options...
jaapv Posted January 2, 2012 Share #17 Â Posted January 2, 2012 It is advised to correct exposure for it it by instructions of the time - it has virtually no light loss, being a single element lens. Link to post Share on other sites More sharing options...
01af Posted January 2, 2012 Share #18  Posted January 2, 2012 It is advised to correct exposure for it it by instructions of the time—it has virtually no light loss, being a single element lens. Actually it's two elements in one group—a very common design for long telephoto lenses with moderate speeds (umm, long-focus lenses, to be precise). True, light loss is exceptionally low indeed. Still, there is nothing to correct in real life, as the difference to 'regular' lenses is in the magnitude of 1/10th on an f-stop—an advantage that is purely academical. There might be a noticable transmission difference when comparing the Telyt 400 mm to a 15-element tele-zoom lens or a 500 mm catadioptric lens ... but that would mean comparing apples to oranges.  I guess the purpose of these 'instructions' mostly was to make the customer feel good about his purchase. After all, the Novoflex Noflexar 400 mm 1:5.6, the Telyt's biggest competitor, was half an f-stop faster, significantly cheaper, and optically almost as good (mechanically even better). However the Noflexar also was two elements in one group. So no, the Telyt 400 mm had no advantage in terms of transmission which might compensate for the slower maximum aperture ... not even partially, much less fully. Link to post Share on other sites More sharing options...
jaapv Posted January 2, 2012 Share #19 Â Posted January 2, 2012 Yes - basically two lenses cemented - or three in the Telyt 800 and Noflexar-T. Typical achromat design. Originally the Noflexar and Telyt 5.6 were virtually identical, then Leica made the choice of improving quality in the corners by losing half a stop and Novoflex added an extra lens for the same reason and called it the Noflexar T. The Noflexar T was more expensive lens. (And yes - long focus lenses ) Link to post Share on other sites More sharing options...
01af Posted January 2, 2012 Share #20  Posted January 2, 2012 .. three in the Telyt 800 and Noflexar-T. It's T-Noflexar, and unlike the Telyt-S 800 mm, it's three elements in three groups—a triplet (that's what the T stands for).   The Noflexar T was more expensive lens. The T-Noflexar 400 mm 1:5.6 was a bit more expensive than the two-element Noflexar 400 mm 1:5.6 but still cheaper than the Telyt 400 mm 1:6.8. Link to post Share on other sites More sharing options...
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