denoir Posted August 7, 2011 Share #201 Posted August 7, 2011 Advertisement (gone after registration) These are a lot of partial explanations rolled into one and frankly I’m not buying all of it just yet. I'm just relaying what I've been told, but I believe it for two reasons. First because it explains the phenomenon quite well and the second because the person that provided is an engineer that works with this stuff professionally and is a veritable encyclopedia when it comes to sensor design. Just to prevent any possible misunderstanding: It is the lowest energy wavelengths (namely red) that penetrate deepest, not the other way round as one might presume. Just like the low energy red light from the sun penetrates deepest into the atmosphere whereas the high energy blue lights gets scattered, creating red sunsets and blue skies. That's correct. It's because a longer wavelength means less interaction with the blocking material. It's the same reason why when your neighbor is playing loud music that you'll hear the bass much better than the treble and why long wave rather than short wave is used for long range radio transmissions. Link to post Share on other sites More sharing options...
Advertisement Posted August 7, 2011 Posted August 7, 2011 Hi denoir, Take a look here Towards an explanation of the Italian Flag Phenomenon. I'm sure you'll find what you were looking for!
jankap Posted August 7, 2011 Share #202 Posted August 7, 2011 Interesting in the sense that the cure in design is obvious - mirror the cells. One wonders why that wasn't done anyway given the symmetrical nature of the sensor.Sandy Mirroring the structure would lead to a break in the middle of the picture! Jan Link to post Share on other sites More sharing options...
sandymc Posted August 7, 2011 Share #203 Posted August 7, 2011 Mirroring the structure would lead to a break in the middle of the picture!Jan Not necessarily. But admittedly, it sure wouldn't be easy, and if the asymmetry is inherent in difference between the red, green and blue cells, then you'd have a problem - you wouldn't want to go from an GBGR cell to RGBG cell in the middle of the sensor, for example. That would require a raw converter that understood the structure. Sandy Link to post Share on other sites More sharing options...
Lindolfi Posted August 7, 2011 Author Share #204 Posted August 7, 2011 One interesting experiment has been left out.Namely a pin hole with the hole out of the center. Or with a lens offering perspective control, the similar effect of course. Jan Has been done, Jan, see this post earlier in this thread: click Link to post Share on other sites More sharing options...
thighslapper Posted August 8, 2011 Share #205 Posted August 8, 2011 Well this explanation fits very well with the observations. As I originally said many months ago, the only possible cause is the assymetry of the bayer grid arrangement and consequent assymetric colour sensitivity. The only thing I find slightly puzzling is why some cameras and lens combinations seem more prone than others ... unless this is due to very subtle variations in lens/sensor alignment..... or microlens misalignment. I can't see it being due to sensor variation, which must be minimal when you consider the method of manufacture. Link to post Share on other sites More sharing options...
jankap Posted August 8, 2011 Share #206 Posted August 8, 2011 Isn't the cause the different angle with which the light hits bayer grid element? Wide angle, tele, high f/stop, low f/stop. See the off-axis experiments above. Jan The foveon sensor seems to have overcome its mirroring problems in the meantime. Jan Link to post Share on other sites More sharing options...
mjh Posted August 8, 2011 Share #207 Posted August 8, 2011 Advertisement (gone after registration) Isn't the cause the different angle with which the light hits bayer grid element? That alone wouldn’t explain it. This has been debated to death in this thread. Link to post Share on other sites More sharing options...
lars_bergquist Posted August 8, 2011 Share #208 Posted August 8, 2011 Well this explanation fits very well with the observations. As I originally said many months ago, the only possible cause is the assymetry of the bayer grid arrangement and consequent assymetric colour sensitivity. The only thing I find slightly puzzling is why some cameras and lens combinations seem more prone than others ... unless this is due to very subtle variations in lens/sensor alignment..... or microlens misalignment. I can't see it being due to sensor variation, which must be minimal when you consider the method of manufacture. Variation betwen different lenses probably has to do with the position of the exit pupil. The old man with watery eyes Link to post Share on other sites More sharing options...
wlaidlaw Posted August 8, 2011 Share #209 Posted August 8, 2011 One interesting experiment has been left out.Namely a pin hole with the hole out of the center. Or with a lens offering perspective control, the similar effect of course. Jan Here is a photo taken with a LeicaGoodies pinhole on the M9. I would estimate the EFOV of this pinhole is roughly equivalent to a 24mm lens. I think it does show Italian flag or at least a red left edge. It also shows that my sensor is overdue a good clean, although the very dark spec is actually an eagle or buzzard in the distance. Wilson 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/153464-towards-an-explanation-of-the-italian-flag-phenomenon/?do=findComment&comment=1759986'>More sharing options...
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