Instructables member Tool Using Animal writes:
For years I’ve wanted to mess around with UV photography. Unfortunately, all the websites on DIY UV seem to assume an infinite amount of money and access to specialized equipment on my part. There are two things that I don’t like, when someone tells me I HAVE to spend a lot of money (quartz lenses starting at $3000) or that i need specialized equipment (Wratten 18A filters, not cheap either). So I set out to do it my way, and here’s my $5 solution to UV wavelength photography.
Read instructions at Instructables
mc at uga at edu posted this comment at MAKE Blog (where I found this link):
I don’t want to be a party-pooper, but I’m not at all sure this is ultraviolet photography. Certainly the light bulb piece is a good substitute for an expensive filter, but is the camera responding to UV or to the small amounts of visible light that also get through? Most camera lenses block UV almost totally. If they didn’t, color rendition would be poor.
I suggest making a UV pinhole camera. Film (black-and-white) is very sensitive to UV if there isn’t any glass in the path.
The optical cement used to glue the elements together in modern lenses does block a good deal of UV already, so I suspect that mc is correct, but I’m not 100%. Anyone have any further insight?
Whilst the bulb is a good idea for film UV photography, digital sensors are very sensitive to IR. Woods filters pass a lot of IR so you are most likely getting an image from IR if using a digital camera for this. Normal lenses often pass a reasonable amount of UV – older ones with uncoated lenses are better, I’ve tested it with a spectroradiometer, but the glues holding elements often fluoresce causing exposure in the visible range also, however this will most likely look a little like flare.