Nichia's latest 365 nm UV LED puts out about 250 mW of light which is quite respectable, IMHO. Now 365 nm is not visible for most of us (if any of us?) so what we do see is that which is excited by the UV and fluoresces as mentioned. Most cameras and lenses have UV filters which would keep the camera from recording illumination based on the UV reflections themselves. I wonder if you can get lenses or if some cameras are actually capable of capturing the UV itself?!? Certainly in high intensities the digital cameras capture the UV itself as I have noticed when I have used UV to excite the H3 vials in images. In addition to a glowing H3 vial, I have seen reds and purples of intensity reflecting off metal. Examples:
I would assume that a UV filter added to the camera could block the red and purple but I never tried it. :shrug:
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At the other end of the spectrum and also not visible to the naked eye is the IR. Now many of the cameras can capture reflected IR light if they don't have filters blocking it. I recall shooting some IR film probably 30 years ago and I had to use the lens on manual focus because IR light is bent differently by the lenses and its focus is different on the film plane than the visible light. I.E. if you focus or auto focus on visible light then the IR scene is out of focus or visa versa.
I recently built a couple IR based PD's using Osram IR LED's (quite powerful).
In the pic below, you can see the PD which is sitting on top of a B/W lipstick video camera which "sees" IR light and in the LCD display, you can see the IR Beam shot centered just to the right of a wall switch. You can also see the wall switch (out of focus) in the digital image and you can see that the Nikon D70 camera that took the picture is not sensitive to the IR light nor is the naked eye. Without the lipstick camera and LDC display, I had no idea that the IR PD was on or what its beam consisted of.
I would imagine that with night vision gear, the IR PD would be quite effective in illuminating a field dark otherwise.
I found that my phone camera does not have such great IR filtering and I could actually use it with the PD to capture an image that was not visible to the naked eye. In the picture above, there was significant ambient light and the shutter speed was pretty quick. Same with the pic below where you can see that the phone camera viewing a PD being illuminated by another IR PD is picking up some of the IR light as well as the ambient visible light. In fact the intensity of the IR here was so great that even the Nikon D70 with a good Nikon AF60 2.8 lens picked up the IR light and represents it as a reddish reflection off the counter and light:
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I think photography is fascinating as it allows you to record both direct as well as reflected light and in ways and means beyond that which the naked eye can capture and yet in other respects no where near as capable as the naked eye. Digital reception and recorded images have so much greater latitude than the films they are rapidly replacing and now with narrow band light sources available from SSL scenes can be illuminated for photographing in ways never before available; or at least with such ease and portability.
