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cryowizardА вот и объяснение дизастера с JMT pix. И как я раньше не додумался? С другой стороны, я привык к Fuji Velvia, а у нее всё-таки UV характеристики более-менее линейные, в отличие, как оказалось, от цифровых сенсоров.
One other thought here. Digital sensors are much, much more sensitive to light that we can't see than film. Where this can really bite you is at high altitudes. The UV levels at high altitudes can cause bizarre color shifts - they may be subtle, as in only a little shift in a color here and a little shift there, but in total they can destroy an image. UV seems to change what each of the three color sensors see in different ways.
I found this to be true of negative film shot at high altitudes versus transparency films on trips in the Himalayas and the Cascades in the US - negative films often had a weird color cast that couldn't be white-balanced away. The UV seemed to screw up each color layer in its own special and different way. If I fixed skin tones, the scenery looked like it was from another planet, if I fixed the scenery, people looked washed out and both more cyan and more magenta. Transparency films, shot on the same trips, same lenses, same UV, skylights, and polarizers, were a lot better at ignoring the impact of UV light, and where they did shift (up at 13,000 feet and above) it was at least consistent enough that white balancing tools could fix it. Maybe transparency films have a sharper cutoff at the UV end of things.
I've found that digital sensors are a lot like negative film, only worse. The couple times I've been at high altitude, and wasn't religious about skylight filters (UV filters are almost useless high up) I got that weird "can't fix it" color cast problem. (This was several years ago, with a CoolPix 5700.) The higher you go in altitude, the UV levels overwhelm the lens' natural suppression of UV. It seems to affect all three channels, and not evenly. I saw the problem worst with polarizers for some reason. A friend of mine just back from a climbing trip in the Alps had the same experience with his Canon 1DS - if he forgot to use skylight filters or at least a UV, images during the brightest parts of the day were almost completely unsaveable. He had two polarizers - a regular B&W and a Kaesemann (sp?), and the images shot through the Kaesemann polarizer were awesome, the regular polarizer, worse than without a polarizer.
I used to swap digital shooting tips with a guy who lived and shot in the Peruvian Andes, and I saw many examples of the high altitude color cast problem from him until he figured out what filters and what times of day worked. Mid day was hideous.
I haven't been up high altitudes in the last few years since my knees can't get me there any more. But if I was going up over 7,000 feet (that's an arbitrary number, but its the altitude where I have pictures that begin to show the effects), I'd be packing skylight filters, UV filters, and Kaesemann polarizers. I lost probably 300 negative film frames shot in Bhutan, where the images would be wonderful if I could just kill the color problems. Thankfully I was shooting mostly transparency film.
I didn't process "Sierra Nevada" when I first read the thread. So, there's one other effect that could be at work.
http://forums.dpreview.com/forums/read.asp?forum=1021&message=19920220
Фотки эти можно подправить в фотошопе, это не страшно.
Но по крайней мере понятно, что камера не сошла с ума.
One other thought here. Digital sensors are much, much more sensitive to light that we can't see than film. Where this can really bite you is at high altitudes. The UV levels at high altitudes can cause bizarre color shifts - they may be subtle, as in only a little shift in a color here and a little shift there, but in total they can destroy an image. UV seems to change what each of the three color sensors see in different ways.
I found this to be true of negative film shot at high altitudes versus transparency films on trips in the Himalayas and the Cascades in the US - negative films often had a weird color cast that couldn't be white-balanced away. The UV seemed to screw up each color layer in its own special and different way. If I fixed skin tones, the scenery looked like it was from another planet, if I fixed the scenery, people looked washed out and both more cyan and more magenta. Transparency films, shot on the same trips, same lenses, same UV, skylights, and polarizers, were a lot better at ignoring the impact of UV light, and where they did shift (up at 13,000 feet and above) it was at least consistent enough that white balancing tools could fix it. Maybe transparency films have a sharper cutoff at the UV end of things.
I've found that digital sensors are a lot like negative film, only worse. The couple times I've been at high altitude, and wasn't religious about skylight filters (UV filters are almost useless high up) I got that weird "can't fix it" color cast problem. (This was several years ago, with a CoolPix 5700.) The higher you go in altitude, the UV levels overwhelm the lens' natural suppression of UV. It seems to affect all three channels, and not evenly. I saw the problem worst with polarizers for some reason. A friend of mine just back from a climbing trip in the Alps had the same experience with his Canon 1DS - if he forgot to use skylight filters or at least a UV, images during the brightest parts of the day were almost completely unsaveable. He had two polarizers - a regular B&W and a Kaesemann (sp?), and the images shot through the Kaesemann polarizer were awesome, the regular polarizer, worse than without a polarizer.
I used to swap digital shooting tips with a guy who lived and shot in the Peruvian Andes, and I saw many examples of the high altitude color cast problem from him until he figured out what filters and what times of day worked. Mid day was hideous.
I haven't been up high altitudes in the last few years since my knees can't get me there any more. But if I was going up over 7,000 feet (that's an arbitrary number, but its the altitude where I have pictures that begin to show the effects), I'd be packing skylight filters, UV filters, and Kaesemann polarizers. I lost probably 300 negative film frames shot in Bhutan, where the images would be wonderful if I could just kill the color problems. Thankfully I was shooting mostly transparency film.
I didn't process "Sierra Nevada" when I first read the thread. So, there's one other effect that could be at work.
http://forums.dpreview.com/forums/read.asp?forum=1021&message=19920220
Фотки эти можно подправить в фотошопе, это не страшно.
Но по крайней мере понятно, что камера не сошла с ума.