Trevor,
I have not seen the NatGeo photographs but some time ago I did some
reflected UV and UV excited fluorescence of caique parrots. Used
Sunpack flashes with Wratten 18A filters to restrict output to long
wave UV. See: http://www.davidhazy.org/andpph/exhibit-caiques.html
Best flash units for UV output are older flash units that did not have
a UV absorbing coating over the flash tubes. Wedding photogs in
particular would need to place UV absorbing filters over heads to
prevent fluorescence of wedding gowns causing them to glow blue and
this would introduce color correction nightmares for the labs.
For long wave UV you don't really need quartz lenses. To do reflected
UV photography you can use the Wratten 18A or equivalent over camera
lens. If your converted to IR camera does not have the IR filter built
into the camera then it probably can be used to record long wave
UV ... otherwise a "regular" camera may be useful. B&W film is an
alternative for reflected UV. For UV excited fluorescence a regular
camera (color film or digital) will work.
Unfortunately the Wratten 18A or equivalent is relatively expensive.
FWIW,
Andy
