pico Posted February 5, 2011 Share #41 Posted February 5, 2011 Advertisement (gone after registration) Yes, it can be any pair of (roughly) complementary colours – red/green, purple/green, blue/yellow …. But if the fringes are all the same colour (such as purple), it cannot possibly be lateral CA. Is it really purple, or violet? I have no image processing software at the moment to read the values. Purple drives me crazy because it can be made with different pairs of colors. Link to post Share on other sites More sharing options...
Advertisement Posted February 5, 2011 Posted February 5, 2011 Hi pico, Take a look here Is this an inordinate amount of CA?. I'm sure you'll find what you were looking for!
mjh Posted February 5, 2011 Share #42 Posted February 5, 2011 Is it really purple, or violet? I have no image processing software at the moment to read the values. Purple drives me crazy because it can be made with different pairs of colors. The really crazy thing about purple is that it has no wavelength (whereas violet has) … Anyway, “purple” fringing can vary between blueish and reddish hues of violet, depending on the camera. Link to post Share on other sites More sharing options...
pico Posted February 5, 2011 Share #43 Posted February 5, 2011 The really crazy thing about purple is that it has no wavelength (whereas violet has) … Anyway, “purple” fringing can vary between blueish and reddish hues of violet, depending on the camera. True! Purple has no specific wavelength. It's a range (or two, depending upon theory) of wavelengths. Neurobiologist Margaret S. Livingstone explains it very well in her book Vision and Art: The Biology of Seeing. I highly recommend it to Black & White photographers in particular. B&W photography is color without hue. Link to post Share on other sites More sharing options...
jaapv Posted February 5, 2011 Share #44 Posted February 5, 2011 I believe that other digital sensors could have done a better job on this type of subject. You may well be right. The trouble is caused by extreme contrast gradients (one pixel white, next pixel black) being misinterpreted by the raw converters' algorithms. Now if you have a sensor with a strong AA filter, or stronger bleeding between the pixels you will not get black-white, but three pixels - black-grey-white, making life easier at raw conversion. The same for the microcontrast and frequency response of the lens. The better the lens, the more fringing. Link to post Share on other sites More sharing options...
vanhulsenbeek Posted February 5, 2011 Share #45 Posted February 5, 2011 So crappy lenses with thick AA filters give good results in extreme situations ? Like politicians, as their results in school were average or less, the more they shout and know better what to do when things go wrong. Who wants to extend this metaphore to armchair CEO's :-) Link to post Share on other sites More sharing options...
Pindy Posted February 6, 2011 Author Share #46 Posted February 6, 2011 I really created a monster. My great thanks to all who weighed in here. I learned a lot. Link to post Share on other sites More sharing options...
plasticman Posted February 7, 2011 Share #47 Posted February 7, 2011 Advertisement (gone after registration) I believe that other digital sensors could have done a better job on this type of subject. Hi Alan You may be surprised to hear that I agree with you about this. I believe that sensors differ in how much/effectively they drain overloading of individual pixels - it's possible that your tests show that your sensors are better than the M8/M9 sensor in dealing with this problem. Link to post Share on other sites More sharing options...
mjh Posted February 7, 2011 Share #48 Posted February 7, 2011 I believe that sensors differ in how much/effectively they drain overloading of individual pixels - it's possible that your tests show that your sensors are better than the M8/M9 sensor in dealing with this problem. According to Kodak’s specs, the sensor in the M8 can handle about 10 EV of overexposure before blooming occurs; the sensor in the M9 would be similar. That’s enough to render blooming a non-issue. But then, purple fringing has nothing to do with blooming. Btw, I don’t think I have ever seen a vendor advertising a sensor as being less prone to purple fringing than previous versions and/or competitors’ sensors. Link to post Share on other sites More sharing options...
plasticman Posted February 7, 2011 Share #49 Posted February 7, 2011 But then, purple fringing has nothing to do with blooming. If you say so, Michael. My understanding is that sensor bloom accentuates the visibility of purple fringing - and that was my point. In any case, I was looking at the original image that started the discussion - and was responding to the claim that the effect would have been equally visible on film - if only film-users looked 'closely enough' at their images on-screen. I stand by my opinion that a film image would not look like this, under the same conditions. Link to post Share on other sites More sharing options...
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