Capturing fluorescent minerals?

Could somebody please explain, in simple terms, exactly what is needed to photograph fluorescent minerals?

Filters? Process?

I'll be using a SuperBright SW UV and a Canon 7D.

Many thanks!

Tim

I have had good experience with about 2-15 second exposure, lens wide-open, and with a strong UV-filter. Keep the lamp behind the lens or shileded from the lens, make sure the filter and the lens do not fluoresce, and watch out for fluorescent dust, backgrounds, etc. Best to use a non-fluorescent background that will appear black in the image. Sometimes extensive color correction, to remove the purple cast in the image, is required as part of post processing. For larger specimens, I hand-hold the lamp and wave it about to get even coverage on the specimen.

Good luck!

That's pretty much what I do, too. I use black glass (fluorescent side down) and black velvet backdrop as a studio. Lenses (or coatings on them) fluoresce, so keep the UV source pointed down and away from the camera or you'll fog up your image. I will shoot at around f10 for better depth of field, leading to longer exposures, sometimes 30 seconds, but that's no big deal (camera is tripod mounted of course). The exposure meter in my Canon Rebel T3i EOS 6000 decides how long to expose. Focus first under regular light as the specimen is typically too dark to see it well enough for manual focus. I always shoot a regular light image of the specimen first, then switch to UV.
Initial photos always come out too blue and that must be removed in photoshop (if any one knows a filter for this please chime in). Best to have the specimen under the UV light next to the computer as a visual reference while adjusting the color balance of the digital image. Do not overexpose or the colors will be saturated leading to poor image and difficulty correcting color.
Once you get the process down you'll love the results.

I've been doing a lot of UV photography of late, with good results. A critical piece of equipment is a Haze 2A filter. This is not the same as the UV filters that many of us routinely use as lens protectors for outdoor work -- those are almost useless for UV photography. The 2A filter completely eliminates the problem of minerals that fluoresce in pastel colors of yellow, pink, etc. showing up as blue on the image.

I too shoot at f11 or so for most specimens (cabinet size) and let the camera decide the exposure time. However, if you are shooting against a black background you'll need to underexpose the entire image or the specimen itself will be overexposed (unless your camera uses a spot meter or center-weighted exposure system). I usually set the camera to underexpose the image by 2 or 3 f-stops and work up from there. Easy to do with digital.

The problem of dust when shooting under LW ultraviolet light is not easy to eliminate completely. For massive specimens I usually wash them under water and scrub them with a soft toothbrush,to remove any dust. If you let the specimens air-dry they will pick up dust again -- it will adhere to the moist surfaces -- so it's best to blot-dry the specimen with a dark towel, one that you know does not fluoresce, or does so only minimally. When taking a long exposure, 10 seconds or more, I keep blowing on the specimen to keep dust particles in the air so they won't register on the image.

I often prefer to shoot against a black background because this is how most of us are used to viewing fluorescent minerals in displays, where they are resting on black cloth, or wood that has been spray-painted black. That works, however, only for those specimens that have no "dead areas" that don't fluoresce. The majority of fluorescent specimens have areas that fluoresce and others that don't, so if you photograph these against a black background you will "lose" the margins of the specimen and have an image of colored patches of light seemingly floating in space. Such photos are almost useless. Thus a dimly fluorescing background is desirable. You have to experiment there, with sheets of colored paper (sold by art establishments as "railroad board").

What I am looking for now is a uniform source of light, something like a small light table, but with a dimmable light source. With such a device, if it exists (or can be built), one could place colored sheets of transparent plastic on the light box, set the light to any desired level of brightness, and position it beneath a frosted sheet of plexiglass, upon which rests the specimen to be photographed. I tried this with a portable light box I already had, but that box uses only two fluorescent tubes and the light is not uniform. Anyone have any suggestions?

You guys rock.

Now I know what to ask for at the camera store; previous attempts to explain what I was up to had them thinking I was insane.

Many thanks!

Let me guess Tim:
"You want to take photos of what???