jaapv Posted July 14, 2016 Share #21 Posted July 14, 2016 Advertisement (gone after registration) For 0% read 0 photons. If it were IR shouldn't you see magenta? But heck, mine is only a theary - I'll happily accept a better one. Link to post Share on other sites More sharing options...
Advertisement Posted July 14, 2016 Posted July 14, 2016 Hi jaapv, Take a look here M (262) colour. I'm sure you'll find what you were looking for!
ralphh Posted July 14, 2016 Share #22 Posted July 14, 2016 Isn't magenta an equal mix of red and blue? I'd expect deep, pure red (that said I really have no idea how IR manifests on a sensor lol). I also don't know if 25 celsius is hot enough to produce IR that anything other than a thermal camera could see What we need is an actual sensor technician, not a photographer/software engineer and a photographer/dentist I suspect such people keep away from online forums lol Link to post Share on other sites More sharing options...
jaapv Posted July 14, 2016 Share #23 Posted July 14, 2016 Yes, Sandy is missed here. Your hypothesis is very easy to test though. Just repeat the exact exposure and development - but this time with a 486 filter on the lens. Link to post Share on other sites More sharing options...
ralphh Posted July 14, 2016 Share #24 Posted July 14, 2016 Wont the rear element - being the same temperature as the front cap - be emitting IR too? Best test would be to put the whole lens in the freezer... volunteers? Link to post Share on other sites More sharing options...
ralphh Posted July 14, 2016 Share #25 Posted July 14, 2016 I've been doing a little research, and it turns out that sensors rarely have balanced native sensitivities across the colours and they are balanced after the fact, meaning one color is often more noisy - usually red or blue (not green as there's twice as many pixles) as they're effectively boosted by different amounts, so have different signal to noise ratios. Link to post Share on other sites More sharing options...
jaapv Posted July 14, 2016 Share #26 Posted July 14, 2016 Yes- but that has to do with the relative densities in the Bayer matrix filters,which cannot have any influence on the present discussion. BTW, to emit significant IR in the sensor's sensitivity range (500-750 Nanometer) the emitting body would need to be at least 2000 degree Kelvin. Link to post Share on other sites More sharing options...
edwardkaraa Posted July 14, 2016 Share #27 Posted July 14, 2016 Advertisement (gone after registration) For what it's worth, I am noticing the 262 has less IR sensitivity than the 240. Link to post Share on other sites More sharing options...
matlep Posted July 14, 2016 Author Share #28 Posted July 14, 2016 Less? I think it looks like more? But I might be wrong of course. Link to post Share on other sites More sharing options...
edwardkaraa Posted July 14, 2016 Share #29 Posted July 14, 2016 Less? I think it looks like more? But I might be wrong of course. I'm quite sure it's less, but obviously still a problem nonetheless. Link to post Share on other sites More sharing options...
ralphh Posted July 14, 2016 Share #30 Posted July 14, 2016 Jaapv, I think you misread / misunderstood my post. Because the sensors have varying sensitivities to different color light, the channels need to boosted by different amounts in order to be capable of producing neutral results, so if the volume is turned up to '10', that might be 8 on blue and 12 on red. Just like two cameras side by side, one with an ND filter, would need higher ISO to get the same exposure. Therefor the different colour channels have different signal to noise ratios, so it's entirely usual that the red channel (or blue) could more more noisy than the others. Seeing as a photograph of the inside of a lens cap is basically just a photo of the sensor noise, it's entirely normal for it to be predominantly one colour. Link to post Share on other sites More sharing options...
jaapv Posted July 14, 2016 Share #31 Posted July 14, 2016 Ah - good lateral thinking, different levels of amplification to compensate for different filter densities. Yes, that is an interesting angle. I seem to remember having read somewhere about noise levels per channel - now to remember where to look it up Link to post Share on other sites More sharing options...
jaapv Posted July 14, 2016 Share #32 Posted July 14, 2016 Isn't magenta an equal mix of red and blue? Magenta is an extraspectral primary colour in the subtractive colour system. (Just for the record ) Link to post Share on other sites More sharing options...
ralphh Posted July 14, 2016 Share #33 Posted July 14, 2016 but this is light, not ink Link to post Share on other sites More sharing options...
ralphh Posted July 14, 2016 Share #34 Posted July 14, 2016 I think we've officially hijacked this thread Link to post Share on other sites More sharing options...
jaapv Posted July 14, 2016 Share #35 Posted July 14, 2016 Yes, but as it is the complementary colour of green in both additive (where it is a secondary colour) and subtractive systems it is the default cast for IR light due to the higher number of green pixels. Link to post Share on other sites More sharing options...
jaapv Posted July 14, 2016 Share #36 Posted July 14, 2016 I think we've officially hijacked this thread Link to post Share on other sites More sharing options...
Maarten Posted July 14, 2016 Share #37 Posted July 14, 2016 Magenta ain't a color: 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! 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/262436-m-262-colour/?do=findComment&comment=3078854'>More sharing options...
matlep Posted July 14, 2016 Author Share #38 Posted July 14, 2016 I'm quite sure it's less, but obviously still a problem nonetheless. I tried looking through my old library with M240 shots, and I cant find any examples where I see IR-issue as clearly as on me example shot in post no.1? Unfortunately I don't have my M240 anymore so I cant do any new comparisons. Link to post Share on other sites More sharing options...
Jeff S Posted July 14, 2016 Share #39 Posted July 14, 2016 I tried looking through my old library with M240 shots, and I cant find any examples where I see IR-issue as clearly as on me example shot in post no.1? Unfortunately I don't have my M240 anymore so I cant do any new comparisons. Discussed often in the past, with photos, as here... http://www.l-camera-forum.com/topic/217200-m240-color-test-oh-oh/?p=2471975 Jeff Link to post Share on other sites More sharing options...
pop Posted July 14, 2016 Share #40 Posted July 14, 2016 Magenta ain't a color: Magenta is not a spectral color, but it's a color nonetheless. None of the mixtures of blue or violet and red are spectral colors. Link to post Share on other sites More sharing options...
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