Alnitak Posted December 2, 2009 Share #1 Posted December 2, 2009 Advertisement (gone after registration) So, my thread on the CV 15mm at the Getty Center turned into a lively discussion of the "red edge" issue that some have seen with their M9s. I was expecting a new WATE to arrive late last week or early this week, and it arrived today. I immediately took it outside and tried a few shots of the blue sky, and as I expected, I did not see any red edge issues. I then got out the CV 12mm and 15mm lenses and did a little bit more experimentation with a gray card. Here are my observations. First, it seems clear to me now that this effect is fundamentally caused by the specific lens-camera combination, and can occur even with lens detection turned off. See these two images: CV 12mm, lens detection turned off: CV 12mm, coded as Leica 21/2.8 11134: CV 15mm, lens detection turned off: CV 15mm, coded as Leica 21/2.8 11134: So, here we see that the cyan drift occurs as expected with both lenses and is most visible when they have not been coded. However, we can also see the red edge appearing, prominently with the 15mm on the left and bottom, with the bottom left corner having a good dose of red. Its much less visible with the 12mm, but its still there. When both are coded as the 21/2.8, the cyan drift and overall vignetting are fairly well-corrected, but we see the red issues become more prominent, as might be expected if they are the result of not quite perfect correction. Now, my camera shows absolutely no red edge issues with my Leica lenses, including the WATE that I got today. Looking through reports of the issue, its almost always the CV and Zeiss lenses that are reported as being problematic. I have found a few reports of people with CV 15's that do not show any red edge, so its not every CV lens or every copy. The only Leica lens that seems to fairly consistently show this issue is the 18/3.8. I did notice on my badly decentered CV 21/4 that the red edge was very prominent. That lens has been returned for exchange. When the new one comes I will check it again. Based on these observations, here are my conclusions: 1) The problem is with the lenses, and not the camera or the correction profiles (with one exception). It appears to be a symptom of decentering in the lenses, no matter how slight. The fact that some copies of the Zeiss and CV lenses do not show the issue indicates that it is lens-specific, and some lenses are just fine. It can't be the camera, or my camera would display issues with the WATE and we would expect the 12mm to show a worse problem than the 15mm, but that's not the case. 2) The exception to #1 is the Leica 18/3.8 where it appears that the default profile in the camera may be overcorrecting a bit for the overall population of lenses. Hence this issue appears with almost every copy of the 18/3.8. 3) I think Leica is doing some basic corrections to ALL images, regardless of lens coding. This correction is why some lenses show the red edge problem--albeit in a much more restrained way--even when lens detection is turned off. This makes sense, as Leica no doubt has to do some work in software to deal with the issues of making a FF DRF work. Its not all done with changes to the sensor. 4) There have been a few isolated cases of other lenses having issues, including some Leica lenses. I believe that these are single cases of lenses with slight decentering issues. In the case of CV, decentering seems to be a common problem, so its seen very regularly with those lenses. Leica presumably has much more precise manufacturing/assembly tolerances and therefore decentering is much less common; rare even. 5) What this means is that we will see a fix in firmware for the 18/3.8 and maybe some tweaks in other lens profiles, but if you use a CV or Zeiss lens that has problems, you will continue to need to rely on CornerFix. I'm hoping to further test this concept of decentering as the primary cause by trying a couple of different copies of the CV 15mm in the coming weeks. Ideally I would be able to try it with more than one M9, but that might be a bit difficult to achieve. OK, time for everyone to let loose and either rip these thoughts to shreds or add to them. Jeff Quote Link to post Share on other sites More sharing options...
Advertisement Posted December 2, 2009 Posted December 2, 2009 Hi Alnitak, Take a look here The M9, lenses and the "red edge" problem. I'm sure you'll find what you were looking for!
thrice Posted December 2, 2009 Share #2 Posted December 2, 2009 Thanks for your analysis Jeff, very helpful information. I have a 25mm Biogon that shows a tiny amount of red edge when coded as 24 asph, I can't do the 28 asph coding because of the bayonet it uses, and I can't be bothered manually selecting every lens in the menu. I do see it from time to time with the 35 lux asph, but not in most real-world shooting. I also have a 50/2.5 CV color skopar that doesn't have any discoloured edges in real-world shots coded or uncoded but i still coded it as a 50 summarit for library management and searching convenience. My 50/1.1 nokton is coded as f/1 noctilux with no detrimental effects. 90 Elmarit-M also shows no real world discoloration but I have that coded as well. Quote Link to post Share on other sites More sharing options...
Alnitak Posted December 2, 2009 Author Share #3 Posted December 2, 2009 Daniel, I suspect that the effect would really only show on wide angle lenses which have a steeper angle of incidence on the edges and corners of the sensor. Quote Link to post Share on other sites More sharing options...
250swb Posted December 2, 2009 Share #4 Posted December 2, 2009 (edited) I have a CV 21mm LTM that generally seems to show red edge depending on the direction of light and perhaps exposure. It doesn't seem to make any difference whether the lens has one of the Leica 21mm lens profiles assigned to it or not. If the light is coming from the left I'll often get red edge. If coming from the right I get no red edge. And if the light is behind me I get no red edge. Add to this my suspicion that exposure makes a difference in that a clearly underexposed image seems to give a predominant red edge, and a well exposed image very little red edge. I use the terms 'under exposed' and 'well exposed' in a lose way because naturally you may want to under expose an image for effect. Despite this, and its not something I can put my finger on to find a cause, sometimes when I would expect red edge I don't get any at all. Steve Edited December 2, 2009 by 250swb typo Quote Link to post Share on other sites More sharing options...
UliWer Posted December 2, 2009 Share #5 Posted December 2, 2009 Thank You, alnitak, for your demonstration! This really raises further question, though I strongly hope that Leica will have a solution by a firmware update soon. Quote Link to post Share on other sites More sharing options...
SJP Posted December 2, 2009 Share #6 Posted December 2, 2009 The WATE is a retrofocus design as are the 24/1.4 , 21/1.4 and the super-elmar. This means that the angle of attack of the light rays on the sensor is not very steep. With the CV12 and CV15 (and a Zeiss mentioned in another thread) the light rays hit the sensor at a steep angle. How about the super-angulon that has similar design if I recall correctly? Sofar I am convinced it is due to the steep angle of attack with some of the wide angle lenses. Recall that a few years ago Leica said that you could not make a digital M at all, for this very reason. The M9 sensor is pushing the boundaries of what is possible. Quote Link to post Share on other sites More sharing options...
Nikkor AIS Posted December 2, 2009 Share #7 Posted December 2, 2009 (edited) Advertisement (gone after registration) I tested a 21 Super Angulon on the M9 and the results where "brutal". Im not buying the problem is with the lens, it's the M9 sensor. I tried several different lens profiles in the M9 menu and none of them helped in any way. And it was not just the edge but the 1/3 of the left side. Im not buying that the lens is at fault because when used on film (negative/slide) the same 21 f4 Super Angulon is incredible. Jeff: From your results, Im a little confused that you think the cyan drift is well corrected:confused:. Are we looking at the same images?. Because from your sample's they all look horrible. It's not just the weird color but the lack of uniform density that Im seeing. Anyways, thanks for posting your finding's. If you go to my Smug Mug site and go to the M9 section you can see some of my sample images with the M9 and the Leica 21 Super Angulon. gregory SmugMug Photo & Video Sharing. You look better here. Edited December 2, 2009 by Nikkor AIS Quote Link to post Share on other sites More sharing options...
thrice Posted December 2, 2009 Share #8 Posted December 2, 2009 (edited) Woops I got confused, cyan drift is because of high incidence, red edge is over correction or some kind of refraction I really have no idea Edited December 2, 2009 by thrice Quote Link to post Share on other sites More sharing options...
JPH1962 Posted December 2, 2009 Share #9 Posted December 2, 2009 Hello! Very usefull comparison! I use Leica as well es Zeiss ZM and CV lenses. In case of my Biogon 21 2.8 I have noticed that the red is visible on the left and the bottom of the Frame - but only when uncoded or coded as 21 Asph. If I code as 21 11134 it is just perfect. That woul dindicate that it is not only a decentering issue. With the Heliar 15mm I make the same observatiosn as you did and the tiny 21 f4 CV is more or less ok when coded as a 28mm 11809. I found differences depending the aperture used. I found that at least with Lightroom it is fairly easy to correct the redish side by adding a colour gradation with a very pale green/blue.... unless one shoots light grey walls that's an acceptable correction whis is further more very simple to do. Anyway - lets enjoy our M9's rather that pixel peep! all the best JPH Quote Link to post Share on other sites More sharing options...
Nikkor AIS Posted December 2, 2009 Share #10 Posted December 2, 2009 (edited) The problem is even worse with lenses like the Super Angulon 21 f4 because it extends way far back into the body. So the angle the light is hitting the sensor from the back element is even more acute. Gregory SmugMug Photo & Video Sharing. You look better here. Edited December 2, 2009 by Nikkor AIS Quote Link to post Share on other sites More sharing options...
Dan States Posted December 2, 2009 Share #11 Posted December 2, 2009 Wouldn't Cornerfix correct this? Quote Link to post Share on other sites More sharing options...
Ario Arioldi Posted December 2, 2009 Share #12 Posted December 2, 2009 Wouldn't Cornerfix correct this? Yes. Cheers, Ario Quote Link to post Share on other sites More sharing options...
chris_tribble Posted December 2, 2009 Share #13 Posted December 2, 2009 Hi - Ario - HOW? Grateful if you could give some input to this posting... http://www.l-camera-forum.com/leica-forum/leica-m9-forum/107751-cornerfix-1-3-0-4-available.html#post1141383 Best Quote Link to post Share on other sites More sharing options...
Ario Arioldi Posted December 2, 2009 Share #14 Posted December 2, 2009 Hi Chris, below there is the link to a previous post of mine showing the effect of using CornerFix on the CV15 files. http://www.l-camera-forum.com/leica-forum/leica-m9-forum/105834-cornerfix-1-3-0-3-available.html#post1117412 The profile was created by means of an home made diffuser shooting at EV +2. Cheers, Ario Quote Link to post Share on other sites More sharing options...
chris_tribble Posted December 2, 2009 Share #15 Posted December 2, 2009 I found that at least with Lightroom it is fairly easy to correct the redish side by adding a colour gradation with a very pale green/blue.... unless one shoots light grey walls that's an acceptable correction whis is further more very simple to do. JPH - now why didn't I think of that. I've now got a preset which applies this specifically for the 18mm Zeiss. I can apply this on import or just apply to those that need. Simplicity itself. MANY thanks... Best C: Quote Link to post Share on other sites More sharing options...
chris_tribble Posted December 2, 2009 Share #16 Posted December 2, 2009 Hi Chris,below there is the link to a previous post of mine showing the effect of using CornerFix on the CV15 files. http://www.l-camera-forum.com/leica-forum/leica-m9-forum/105834-cornerfix-1-3-0-3-available.html#post1117412 The profile was created by means of an home made diffuser shooting at EV +2. Cheers, Ario Ario - thanks also for this. Could I impose on you to explain what you mean by a "home made diffuser"? Is this something you put over a flash unit? I'm thinking of experimenting with the SF24D and a softbox... Thanks C: Quote Link to post Share on other sites More sharing options...
jrh68uk Posted December 2, 2009 Share #17 Posted December 2, 2009 I'm keeping a beady eye on this issue as it's the main reason I haven't yet ordered an M9. The problem I have with it is that it always seems to be on the LHS. Surely that must mean that it can't be down to lens de-centre alone, since you'd expect to see as many on the RHS as on the LHS. This makes me think that it must be a hardware sensor (or perhaps a sensor alignment with lens throat) issue. Quote Link to post Share on other sites More sharing options...
Ario Arioldi Posted December 2, 2009 Share #18 Posted December 2, 2009 Yes Chris, something like that. The idea was to get someting evenly illuminated to shoot against, and I've used a sheet of styrofoam to create a cap for the lens. Cheers, Ario Quote Link to post Share on other sites More sharing options...
chris_tribble Posted December 2, 2009 Share #19 Posted December 2, 2009 Yes Chris,something like that. The idea was to get someting evenly illuminated to shoot against, and I've used a sheet of styrofoam to create a cap for the lens. Cheers, Ario Ah... OK - I'll have to work on this! Best C: Quote Link to post Share on other sites More sharing options...
JPH1962 Posted December 2, 2009 Share #20 Posted December 2, 2009 (edited) @Chris: you are welcome.... @Ario: now that you said you used styrofoam I understand the pattern I could see on your examples of the other thread. Back at the time where I earned my living as photographer for a well known swiss studio-flash manufacturer I used large Perspex sheets to perfectly diffuse the strobes to create smooth gradations in glas, silver or others... Styrofoam even used as reflector left often a visible structure. that perspex material would be perfect - I just don't remember the densities used.. . the lesser ones were poor and prone to stange coloureffects... just a hint. I add twice the same pic just as an example: one shot with 28mm coding without colour gradation to correct - and the second is the same shot but with the gradatio n apllied. I have no presets... don't know how to do it... and like anyway adapting to each pic i want to correct. Time for a tea! JPH 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! Edited December 2, 2009 by JPH1962 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/105486-the-m9-lenses-and-the-red-edge-problem/?do=findComment&comment=1137725'>More sharing options...
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