colorflow Posted February 15, 2007 Share #1 Posted February 15, 2007 Advertisement (gone after registration) Has anyone seen this type of reflection before? It's the red reflection in the wire wheels, especially the rear one. Chromatic abberation, IR? There was nothing red in the vicinity. Also saw same reflection using early Lux 50 on a different day and location. Could not get rid of it in Lightroom or C1LE. ISO160, Cron 28 at f8, no IR filter. Thanks in advance, Alan 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/16281-whats-this-red-reflection-in-the-wire-wheels/?do=findComment&comment=172103'>More sharing options...
Advertisement Posted February 15, 2007 Posted February 15, 2007 Hi colorflow, Take a look here What's this red reflection in the wire wheels?. I'm sure you'll find what you were looking for!
tokenfemme Posted February 15, 2007 Share #2 Posted February 15, 2007 Purple fringing? It is when purple tones appear in the image on the border between light and dark areas (trees against a bright sky are a common test shot); it is due to activity on the sensor, and when there is no anti-aliasing in the system. That was, for me, like a first sentence written in a foreign language. Someone else can probably explain it better! Best sb Link to post Share on other sites More sharing options...
colorflow Posted February 15, 2007 Author Share #3 Posted February 15, 2007 Purple fringing? It is when purple tones appear in the image on the border between light and dark areas (trees against a bright sky are a common test shot); it is due to activity on the sensor, and when there is no anti-aliasing in the system. That was, for me, like a first sentence written in a foreign language. Someone else can probably explain it better! Best sb Thanks. Yes, I think that's what it is. I've seen purple fringing before, but not this bad. I have already worked on minimizing it in Lightroom. Alan Link to post Share on other sites More sharing options...
J_Brittenson Posted February 15, 2007 Share #4 Posted February 15, 2007 Probably chromatic aberration in IR. Link to post Share on other sites More sharing options...
Lode Posted February 15, 2007 Share #5 Posted February 15, 2007 Purple fringing is most likely a color artifact caused by the interpolation of the color data in digital cameras using a bayer pattern (CFA). It doesn’t occur on film. Link to post Share on other sites More sharing options...
Guest WPalank Posted February 15, 2007 Share #6 Posted February 15, 2007 Alan. I opened it as a jpeg into the Camera RAW dialogue box in CS3 and could only get rid of it by going into the Clibration tab and playing with the red hue and saturation slider. 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/16281-whats-this-red-reflection-in-the-wire-wheels/?do=findComment&comment=172142'>More sharing options...
Jamie Roberts Posted February 15, 2007 Share #7 Posted February 15, 2007 Advertisement (gone after registration) ACR is very bad for this right now. C1, in my experience, is way better. It's called birefringance. This particular shot also has nothing to do with IR; plenty of other digicams and lenses exhibit this tendency in high contrast situations (like all of Canon's fast glass on any Canon dSLR). But ACR / LR currently make it worse. I have some shots developed in ACR that actually look worse than the JPEGs (the JPEGs, in fact, show none of the fringing ACR does). C1 also doesn't show the problem, in my case, anyway. Link to post Share on other sites More sharing options...
J_Brittenson Posted February 15, 2007 Share #8 Posted February 15, 2007 Birefringence... Have you ever seen a demonstration of birefringence? Link to post Share on other sites More sharing options...
colorflow Posted February 15, 2007 Author Share #9 Posted February 15, 2007 ACR is very bad for this right now. C1, in my experience, is way better. It's called birefringance. This particular shot also has nothing to do with IR; plenty of other digicams and lenses exhibit this tendency in high contrast situations (like all of Canon's fast glass on any Canon dSLR). But ACR / LR currently make it worse. I have some shots developed in ACR that actually look worse than the JPEGs (the JPEGs, in fact, show none of the fringing ACR does). C1 also doesn't show the problem, in my case, anyway. Jamie, you are right. Cockpit error when I was in C1. Used properly it shows none of the fringing. ACR/LR is really bad for this. I was going to purchase it, but now have second thoughts. What is causing this "birefringance"? Alan Link to post Share on other sites More sharing options...
carstenw Posted February 15, 2007 Share #10 Posted February 15, 2007 Alan, wait for the final release of Lightroom. It is meant to be improved. Link to post Share on other sites More sharing options...
colorflow Posted February 15, 2007 Author Share #11 Posted February 15, 2007 So my question now is - is it the sensor or is it the processing software? Alan Link to post Share on other sites More sharing options...
carstenw Posted February 15, 2007 Share #12 Posted February 15, 2007 To answer that, try varying a variable. Change processing software and see what happens. Link to post Share on other sites More sharing options...
colorflow Posted February 15, 2007 Author Share #13 Posted February 15, 2007 Carsten, that's a good way to look at the problem. C1 shows no problem, while I couldn't get rid of it in Lightroom no matter what I did. So to answer my own question - it is an artifact of the sensor that can be eliminated when properly handled in software. Alan Link to post Share on other sites More sharing options...
B&W Posted February 15, 2007 Share #14 Posted February 15, 2007 I also get this problem from time to time even with C1LE 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/16281-whats-this-red-reflection-in-the-wire-wheels/?do=findComment&comment=172871'>More sharing options...
J_Brittenson Posted February 15, 2007 Share #15 Posted February 15, 2007 What is causing this "birefringance"? Must be retardation! Link to post Share on other sites More sharing options...
colorflow Posted February 15, 2007 Author Share #16 Posted February 15, 2007 I also get this problem from time to time even with C1LE Your photo is what I understand to be purple fringing. I used Lightroom/Lens Corrections/Reduce Fringe and was able to eliminate some of it. But I was not able to reduce the red reflections (birefringance) in my photo with the same steps. 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/16281-whats-this-red-reflection-in-the-wire-wheels/?do=findComment&comment=172981'>More sharing options...
jaapv Posted February 15, 2007 Share #17 Posted February 15, 2007 This looks more like chromatic aberration. I see both red and green edges.What lens was this taken with? Link to post Share on other sites More sharing options...
colorflow Posted February 16, 2007 Author Share #18 Posted February 16, 2007 Mine was taken with Cron 28 ASPH. No IR filter. See Jamie's reply. He knows what this is. Alan Link to post Share on other sites More sharing options...
Jamie Roberts Posted February 16, 2007 Share #19 Posted February 16, 2007 Alan-- Yep, I know what it is, but I can't spell it. It's birefringence, and you can read about it here (or at part of it!): Birefringence - Wikipedia, the free encyclopedia The way it was explained to me (by a Canon technical guy, actually) all digital sensors interact with lenses and light scattering (especially wide open lenses) in different ways than film (duh!). Because they're actually silicon, they induce a prismatic abberation from time to time, especially in areas of high contrast. One of the common results, is this fringing at the sensor level. It's not technically chromatic abberation, which, if I understand correctly, is actually a lens flaw exacerbated by digital (but can show up on film; think Holga lenses!). A great article on this here: Chromatic aberration - PanoTools.org Wiki Scroll down for ways to distinguish different kinds of fringes... Anyway, the interaction of the lens design with the sensor is what causes this particular coloration to show up, not the Leica glass @ Jan--I've seen this many times, and have a series of PS actions just to deal with it! For example, on the current Canon pro sensor cameras, their 50 1.2L, 50 1.4 and 85 1.2L all create "purple and green fringing" on digital but not on film. In other words, its the lenses with the sensor. However, some lens combinations are more susceptible than others; when I switched a Leica R 80 Lux in for the 85 Canon 1.2L on the 1ds2, the fringing virtually disappeared (only in specular highlights). Now, neither the Canon glass NOR the Leica 80 are apochromatic lenses; yet one set fringed (expected) but the other (Leica) did not. Same for the 50 Summilux, which on the R side is also not apochromatic, IIRC. Typical chromatic abberation doesn't show up with APO lenses, but something else must be going on too, aside from the glass characteristics (which are obviously quite different). So it's not IR, and it's not CA, at least technically (or according to Canon); it's light bouncing around at the sensor level (in areas of high exposure and contrast). And Jan, if it's not birefringence, and the Canon guys got it wrong, I'm happy to be corrected. In fact, here's a whole discussion of how *all* of these artifacts are caused by "chromatic abberation"...(well, they are chromatic and they are aberrations. I'm just relaying what the Canon folks told me). Chromatic aberrations Frankly, I'm surprised at how generally immune the M8 is to this (and ACR is inducing it's own artifacts, for sure. I'm sure they'll fix this though). Link to post Share on other sites More sharing options...
colorflow Posted February 16, 2007 Author Share #20 Posted February 16, 2007 Jamie: Whatever this is, must be relatively simple to correct since C1 automatically recognizes it and corrects it. Just surprised that PS LR not only does not automatically correct it, but doesn't provide manual tools to deal with it either (at least I couldn't do it). Alan Link to post Share on other sites More sharing options...
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