同一个相机， 如果没有内置滤光镜， 就可以拍出4种不同“色”来： 普通： 红外滤镜S8612 紫外: 红外滤镜S8612+ 可见滤镜UG11 红外： 可见滤镜UG11 A play of colors under various light conditions. Acronyms: UV=ultraviolet, VIS=visible light, IR=infrared. Method： Camera: Panasonic DMC G5 full spectrum converted. IR: camera + UG11 (no VIS, UV is negligible) UV: camera + UG11 + S8612 (no VIS, no IR, only UV allowed) VIS: camera + S8612 (no IR, UV is negligible) Full Spectrum: camera only (all light allowed in, but CCD sensitivity is low to UV so most of the time UV negligible, mainly IR+VIS). UV and VIS shots are white balanced in camera, IR is either converted to black and white or using Kelvin scale in side the camera. Full spectrum photos are simply balanced with automatic. Exposure adjusted by photoshop but no other changes. 1. I took four petals, each from one color, all flowers are begonias. Under infrared light, you cannot really tell which flower has what: they are supposed to be white, yellow, pink and red. Can you guess which one is white and which is red, at least? I think not. 
2. This is under UV. Now we see something more interesting. The top one is nearly black while the lower one is light blue. Still I would have guessed that the top one is red which would be wrong. 
3. Now we see which is which! I am a bit surprised that red is lighter than yellow under UV. If I desaturate this photo to make it black and white, red will be slightly darker than yellow. 
4. Under full spectrum (with visible light + IR +UV, although UV is really at very low levels), the color more or less the same as normal (what we see) with a pinkish tint to everything. I have not tried white balance this with a Teflon to see if it would look better. 
5. now we play with some real flowers. Under IR, they all looked the same -- we cannot tell what color they will be. 
6. Under UV, the geranium is blue, evening primrose retained its yellow (but remember since the true yellow is blocked by UG11, this yellow is a false color with certain wavelength of UVA). The three types of asters all are highly UV absorptive. 
7. Now we can see the asters, one is a tick-seed (Coreopsis), a daisy (Chrysanthemum), and a flee-bane (Erigeron sp). They are either yellow or white, of course, since there is no such a thing as a black aster (with the exception of some dahlias so deep purple they can be almost black). 
8. Full Spectrum shot of the same flowers. Happy July 4th!  |
666: Are you sure it's not leaking IR?
waspking: different chemicals would absorb UV and visible light differently...
I have seen red -> white, yellow -> black, yellow -> yellow, yellow -> green, red ...
666: It's interesting that under uv yellow shows up as yellow in one instance, but as black in another. I am curious what mechanisms are at work.
panda: if I am not mistake, there are a lot of effect you can do with photoshop, maybe UV is in there
waspking: 不可能啊。 你怎么知道UV底下的颜色， 去Photoshop？ 这是现实， 不是想象， 当然你的眼睛看不到的。
panda: the color looks pretty ugly.
could you just photo shop to this effect instead buying lenses?
666: Under uv light, whites should appear darker than blacks. Is this a politically correct scientific experiment?
666: I'm guessing that may be the image sensor is responsive to the harmonics of visible light wavelengths. And, your uv spectrum covers those of the harmo ...
I think it is just a coincidence though that the original yellow is also yellow under UV though..the yellow below becomes black, for example. and red cactus flowers become UV-yellow.Powered by Discuz! X3.4
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