bebert Posted July 9, 2007 Share #1 Posted July 9, 2007 Advertisement (gone after registration) Dear all, I just received my UV/IR filters from Leica and shoot some pics over the week-end with the filters on (35mm and 50mm asph not coded). Surprisingly, when developping the raw files in C1 3.7.7 and using the UV/IR generic profile, the blacks (with natural light) of synthethic material appear quite purple. The only profile which give a clear black (but a lower saturate image for the other colors) is the JHR v1 profile. I am missing something? I thought that the filters would allow me to have true blacks... Thank you for your advice. JM Humbert Link to post Share on other sites More sharing options...
Advertisement Posted July 9, 2007 Posted July 9, 2007 Hi bebert, Take a look here UV/IR generic filters and C1 pro. I'm sure you'll find what you were looking for!
Guest guy_mancuso Posted July 9, 2007 Share #2 Posted July 9, 2007 In menu set for IR/UV on with 1.102 Link to post Share on other sites More sharing options...
fordfanjpn Posted July 9, 2007 Share #3 Posted July 9, 2007 In menu set for IR/UV on with 1.102 I didn't need to do that (I don't have coded lenses). I just banged the filter on the lens and the magenta problem was solved. Sounds like something else is happening here. Bill Link to post Share on other sites More sharing options...
sps Posted July 10, 2007 Share #4 Posted July 10, 2007 I'm not having this problem, and am doing the same as you except having lens detection and UV/IR set to on. I keep it this way even with uncoded lenses. As I haven't tried it any other way, I cannot attribute your problem to this, but give it a try. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted July 10, 2007 Share #5 Posted July 10, 2007 If the filter is on you should have the UV/IR menu on regardless of code. It corrects for the filter being on the lens. When it detects the wide angles than it corrects for the corners. So even if you have a 75 lux uncoded on with filter i always leave the menu set for UV/IR ON. The firmware is tuned for the filters Link to post Share on other sites More sharing options...
wattsy Posted July 10, 2007 Share #6 Posted July 10, 2007 If the filter is on you should have the UV/IR menu on regardless of code. It corrects for the filter being on the lens. When it detects the wide angles than it corrects for the corners. So even if you have a 75 lux uncoded on with filter i always leave the menu set for UV/IR ON. The firmware is tuned for the filters Yes, but having this set to off isn't going to suddenly turn blacks purple. The original poster's problem sounds more fundamental. Jean-Marc, is it possible that you are inadvertently using normal UV filters rather than UV/IR? My experience of the UV/IR filters (both Leica branded and B+W 486 filters) is that they kill the magenta blacks once and for all - irrespective of firmware and menu settings. They do sometimes introduce annoying filter reflections but that's another story.. Link to post Share on other sites More sharing options...
Guest guy_mancuso Posted July 10, 2007 Share #7 Posted July 10, 2007 Advertisement (gone after registration) Ian just thought it maybe Jamies profile which is tuned i believe to rid the magenta cast. This maybe the issue. Link to post Share on other sites More sharing options...
Jamie Roberts Posted July 11, 2007 Share #8 Posted July 11, 2007 Well, it's hard to wade in here without seeing the offending photograph, but, FWIW, yes, that original profile does get rid of a lot of magenta within a very narrow bandwidth. It's more aggressive than need be with the IR filters on. Still, as we all know, blacks are rarely really RGB or LAB "black" out of any camera. Unless you're shooting a colour checker under controlled light, most black surfaces aren't neutral either (which is why you buy a colour checker!) as in, say, RGB 12, 12, 12....(though if they're clipped they're going to be 0,0,0). So I'm not sure what the posters issue is. For example, if you were shooting a black semi-reflective object in mixed light--mostly tungsten but with some daylight seeping in, I could easily see the blue and red from the two different light colours making that thing appear magenta. It isn't, but no IR filter will fix your white balance, if you get my drift! Now he says he's shooting under daylight, so maybe he's got a super strong source of IR somewhere.... but I find that hard to believe in daylight, compared with, say, tungsten. I also follow Guy's advice on this, and unless I'm shooting without filters for a reason, I just leave UV IR on. The new C1 UV / IR profile is also really very good, I think. While I'm still making more here, I'm using the C1 provided one more than anything else. Jean-Marc--have you got the RAW file available? I'd love to take a look... Link to post Share on other sites More sharing options...
sean_reid Posted July 11, 2007 Share #9 Posted July 11, 2007 Dear all, I just received my UV/IR filters from Leica and shoot some pics over the week-end with the filters on (35mm and 50mm asph not coded). Surprisingly, when developping the raw files in C1 3.7.7 and using the UV/IR generic profile, the blacks (with natural light) of synthethic material appear quite purple. The only profile which give a clear black (but a lower saturate image for the other colors) is the JHR v1 profile. I am missing something? I thought that the filters would allow me to have true blacks... Thank you for your advice. JM Humbert Hi JM, Use a WhiBal to double check your color balance. If the subject really is black it really should be very close to black with an IR-cut filter mounted. Double check the easy things first, ie: the exact color of the subject and, very importantly, that you have absolutely neutral white balance. Don't count on the auto white balance in any camera nailing color balance perfectly. I think if you remove the variables here, you'll see that the filter is actually doing its job. Without a WhiBal, Expo Disc or some other absolutely neutral source, one can't make accurate tests of this. To the best of my knowledge, setting the lens detection to "On" or "On + IR/UV" will have no effect on files made with uncoded lenses (unless the code sensor accidentally picks up a code from a screw in the lens, etc.) Many people do leave this set to "on" or "on+UV/IR" all the time but I don't believe it has any effect at all unless it detects a lens code. The only other issue I can think of, as Jamie mentioned, is an unusually powerful source of IR reflecting from the subject. That's pretty rare. Cheers, Sean Link to post Share on other sites More sharing options...
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