vikasmg Posted November 19, 2006 Author Share #21 Posted November 19, 2006 Advertisement (gone after registration) Lens coding could be the drawback of using non Leica wides on the M8. There's a clarification from a Leica rep on the Poulat Photography site that lens coding only has an effect on the vignetting problem. Infact I understand that lenses longer than 28mm focal length don't need the coding except that it would provide coorrect data about the lens in EXIF... - Vikas Link to post Share on other sites More sharing options...
Advertisement Posted November 19, 2006 Posted November 19, 2006 Hi vikasmg, Take a look here Wide Angles on an M8 . I'm sure you'll find what you were looking for!
vikasmg Posted November 19, 2006 Author Share #22 Posted November 19, 2006 >>Has anyone tried a filter held in front of the CV 15 (no way of mounting it of course)?<< Wasn't sure what you meant, never actually having seen this lens before, Looked at the Zeiss web site. Surely, that's a lens shade sticking out there? The specifications lens a filter threat of M 72 x 0.75 ... - Vikas Link to post Share on other sites More sharing options...
chrism Posted November 19, 2006 Share #23 Posted November 19, 2006 The only way to get a filter on the CV 15 is to use this device: Chris Link to post Share on other sites More sharing options...
glenerrolrd Posted November 19, 2006 Share #24 Posted November 19, 2006 There's a clarification from a Leica rep on the Poulat Photography site that lens coding only has an effect on the vignetting problem. Infact I understand that lenses longer than 28mm focal length don't need the coding except that it would provide coorrect data about the lens in EXIF... - Vikas If thats true you will have a Cyan corners when use a cut filter because it blocks some of the Red spectrum as well as the IR. The firmware fix has not been released to the field ( at least as of Friday ) . I was told by the Leica rep at a Leica days event on Friday night...the solution will require (1) a firmware upgrade (2) 6 bit coding ..for wideangles (3) IR cut filters . Leica is working hard on the supply problem (availability) for the filters. No mention of any changes to the camera/sensor itself. So 6 bit becomes an issue for Zeiss or CV lenses to engage the firmware processing..that is getting it right in the camera. Link to post Share on other sites More sharing options...
sean_reid Posted November 19, 2006 Share #25 Posted November 19, 2006 how do you think they will handle the 16-8-21 tri elmar? only one 6bit code to read so you either have to enter it or they have to pick a compromise std focal length? I don't know yet but I'll be testing it this fall. I'm interested in knowing this as well. Cheers, Sean Link to post Share on other sites More sharing options...
gurtch Posted November 19, 2006 Share #26 Posted November 19, 2006 >>Hope this helpful. I bought the ZM 21 for use with the M8, but I have not yet received the camera, so have not personally tried it.<<Well Dave, Tuesday morning at 10:30am (why can't these guys open earlier!) I'll have my M8 but no 21. If I didn't live on the other side of the planet, we could help each other out :-) Thanks for the help. Vikas: I agree---if we were near each other I would gladly lend you my ZM 21mm to hang on your M8 to try it out! Good luck!! Dave Link to post Share on other sites More sharing options...
vikasmg Posted November 20, 2006 Author Share #27 Posted November 20, 2006 Advertisement (gone after registration) That looks so retro-cool :-) - Vikas Link to post Share on other sites More sharing options...
vikasmg Posted November 20, 2006 Author Share #28 Posted November 20, 2006 >>So 6 bit becomes an issue for Zeiss or CV lenses to engage the firmware processing..that is getting it right in the camera.<< Well, I'll have the Zeiss 21 in a few days and the M8 tomorrow. So I guess I'll find out Real Soon Now.... - Vikas Link to post Share on other sites More sharing options...
vikasmg Posted November 20, 2006 Author Share #29 Posted November 20, 2006 I've bought a ZM 21mm on line last night. Figured it cost less than flying over to try yours out :-) - Vikas Link to post Share on other sites More sharing options...
gurtch Posted November 20, 2006 Share #30 Posted November 20, 2006 I've bought a ZM 21mm on line last night. Figured it cost less than flying over to try yours out :-) - Vikas good luck Vikas! Dave in NJ USA Link to post Share on other sites More sharing options...
lxlim Posted November 20, 2006 Share #31 Posted November 20, 2006 Hi Vikas, I'm from Singapore too. Where are you getting the M8 from and if you don't mind how much are you paying for it? I'm not a leica user yet but considering it. Perhaps we could meet up sometime Alex Link to post Share on other sites More sharing options...
scott kirkpatrick Posted November 20, 2006 Share #32 Posted November 20, 2006 I can certainly imagine that controlling vignetting was uppermost in their minds when designing the lens so, as you say, they may have gone for telecentric. It is certainly quite a long lens. It may well be that the design and the limited "zoom" range meant they did not need to differentiate between focal lengths. That was before 486s came into their world and as Seans results show, there is a big difference between a 28 and a 21 so that moving from 21 to 16 will be worse still. I'm also wondering whether correction is possible at extreme wide-angles. It may be that the effect is non-linear with angle, like a trig tan function, for example. The DMR with coded lenses corrects for the red vignetting due to its dichroic IR filter as well as for overall light falloff at the edges, and since the 16-21 TE seems to be pretty telecentric, the difference in the range of angles seen at the sensor as the focal length changes may not change much at all. This would depend on the change of the exit pupil position, and I have no clue how much it moves -- maybe not at all? So those users should not have much of a problem finding a good compromise setting for the TE. Putting the dichroic filter in front of the lens the angle variation is controlled by the focal length, and the cutoff wavelength moves to shorter (more visible) values as cos (angle). That's going to be hard to correct unless Leica lets us input the desired focal length, but such choice will allow approximating other lenses as well, so let's hope they do. Until things get extreme, the red vignetting correction is pretty mangeable and won't have the unpredictable side effects that trying to adjust red and blue channel intensities to correct for an unknown amount of added IR will have. You just increase the strength of the red signal uniformly around each circle of points at constant angle. The correction factor is derived from the fraction of the expected red signal (some assumptions here) that would be cut off because the filter's edge has moved up into the visible. Unless you photograph spectrally pure crimson orchids, this should be a good estimate to use for correcting, and only butterfly and orchid fanciers need to post process. scott Link to post Share on other sites More sharing options...
vikasmg Posted November 20, 2006 Author Share #33 Posted November 20, 2006 Hi Vikas, I'm from Singapore too. Where are you getting the M8 from and if you don't mind how much are you paying for it? I'm not a leica user yet but considering it. Perhaps we could meet up sometime Alex Hi Alex. Cathay Photo at Marina Square. Ask for Simon. I'm ashamed to say I've forgotten the price (Simon quoted it to me on the phone when I bought it. Around Sing$7,000) I think I may have bought their last one. The next batch is due in around Christmas. Email me on vikas@singnet.com.sg if you like. Cheers. - Vikas Link to post Share on other sites More sharing options...
lxlim Posted November 20, 2006 Share #34 Posted November 20, 2006 Hi Alex. Cathay Photo at Marina Square. Ask for Simon. I'm ashamed to say I've forgotten the price (Simon quoted it to me on the phone when I bought it. Around Sing$7,000) I think I may have bought their last one. The next batch is due in around Christmas. Email me on vikas@singnet.com.sg if you like. Cheers. - Vikas Thanks, I know the Cathay guys. Alex Link to post Share on other sites More sharing options...
ho_co Posted November 20, 2006 Share #35 Posted November 20, 2006 Concerning the 16-18-21: Since the front element protrudes greatly from the front of the mount, anybody got an idea how we would mount a filter? Leica literature always shows (only) this lens with its hood attached; and the one 'first look' I've seen on it says the front part of the mount is painted red to remind us not to set it down on its convex front element. Add to that the fact that it's the angle of incidence of the image-producing light that creates the cyan corners. Looks to me as if we won't have to (be able to) purchase an IR-Cut for the wide Tri-Elmar. Unless of course Leica comes out with a custom version.... In that case we might not be able to purchase the filter for another reason--the cost! HC Link to post Share on other sites More sharing options...
steve_l Posted November 20, 2006 Share #36 Posted November 20, 2006 There was a post somewhere here that talked about the Tri-Elmar requiring a "filter adapter" to mount the filter.... Link to post Share on other sites More sharing options...
steve_l Posted November 20, 2006 Share #37 Posted November 20, 2006 And it is listed in th tech info as using a 67mm filter....so I guess there is a way. Link to post Share on other sites More sharing options...
wparsonsgisnet Posted November 20, 2006 Share #38 Posted November 20, 2006 I have assumed that someone will figure out how to dupicate the 6 bit coding on alternative maker lenses( or possibly Leica will allow for direct entry of the lens selected thru the menu) . This would then allow the firmware to make in camera corrections appropriate for this focal length. That will cover the 21 at least partially. But for say the new zeiss 18 or the CV 15 we may be out of luck ? I believe I saw something about making this coding available on the RangeFinder Forum. It seems likely, however, that lenses of a given focal length but from different mfrs will have different cyan footprints at the edges. Since there is IR sensitivity in the DR-1 and, now, in the M8, it is expectable that there will be corrections available either for different mfrs' lenses or that will allow we beleagered users to dial in the radius, slope, and degree of cyan correction in a fairly user-friendly fashion. I would prefer the latter solution: enabling the user to post-process for this effect as desired. This would allow us to design our own degree of correction (thus correcting for sample differences in sensors) as well as to allow artistic license (we each see our pictures differently). We should hope that the effect is simple and circular, rather than oval or some other geometric distortion that differs across lens brands. In his discussion of this topic, Sean Reid showed the cyan effect quite clearly. I confess to both liking and disliking the effect. That is, it's subjective. Since we are expecting new firmware for the M8, existing M8 correction for cyan shift is not pertinent. And, continuing in the vein of user-preference, I certainly would prefer to control this myself, probably on a picture-by-picture basis. Vignetting in the M8 may be largely corrected by the offset lenses on the sensor. In any case, this effect should easily be handled by flexible, user-adjustable software, as described above. It clearly looks as if IR-blocking filters are going to be required. It's not clear that vignetting or cyan shift is a problem that needs to be handled in the camera. Regards, Link to post Share on other sites More sharing options...
marknorton Posted November 20, 2006 Share #39 Posted November 20, 2006 Yes, the new TE has a filter adapter ring which allows the fitting of a 67mm filter, the largest of any M lens. This lens is going to be a tough nut to crack. The concern I have is that the cyan correction will depend both on the lens focal length/formulation and on the actual filter used. You can easily imagine that different makes of filter will create different levels of cyan requiring specific profiling. Maybe OK with a Leica filter on a coded Leica lens but what about an XYZ filter on an uncoded CV lens? Overall, I think it's a mess. I can see that IR cut filters will address the magenta problem but will they create as many problems as they solve? Link to post Share on other sites More sharing options...
steve_l Posted November 20, 2006 Share #40 Posted November 20, 2006 Mark- Only for those of us who shoot wide..... Not too many, give Leica's belief that 32mm FOV was all they needed in the viewfinder.... Link to post Share on other sites More sharing options...
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