RE: UV Fluorescence Photography

["Jason Revell (in5)" <jason.revell@xxxxxxxxx>]

Rolland,

What sort of UV (black lights) are they?  Their are two basic sort's; BL and
BLB.

BL are the unfiltered ones often used for Alt. Printing and give off what
appears to be a blue/white light and look white when not switched on.
BLB are filtered, are usually the ones used in pubs and theatre for UV
effects.  These give off  blue/purple light when on and look a dark blue due
to the filters when not switched on.

These bulbs both give off the wavelengths of light you need to the
fluorescence but the BL give off  visible light as well.  So if you are
wanting a dark/black background or just the fluorescence to show use the
BLBs.

Metering for the fluorescence will be your problem, we can only see it when
the lights are turned down in a room so it is very dark in terms of
photographic light.  I use a exposure of 1 min at f5.6 when photographing
the works of art here (using 100 asa film).  This is when they are light by
4 x 4ft BLB tubes in reflective housings at about 1.4 meters.  I think you
might find you are using slightly more light and your fluorescence will be
brighter than mould and varnish.  On this basis I would suggest that you
bracket from about 1/4 to 30 secs at f5.6 or equivalent exposures, this is
about the only way.

Film to use would be ANY.  Your fluorescence is 'visible' light so all film
will record it.  I would however say you are better using daylight film
rather than tungsten.  Also if your tubes are the BLB's ( and to a lesser
extent BLs) you will find you get quite a lot of UV light in the background
showing a blue as films are still sensitive to UV light.  To avoid this you
will need to place a yellow or near yellow ( I use a wratten 2E) over then
lens to block out the UV light the film is sensitive to, so only the
fluorescence is recorded.   A normal UV(0) filter does not block long enough
wavelengths to have any effect with this blue 'fogging'.

Also, just one last thing.  Remember that UV light is harmful to your eye's,
so don't stare into your light bank and some form of eye protection
(sun-glasses for example) would be strongly recommended.

I hope this helps you, and let me know if you have any further questions.

Jason
jason.revell@xxxxxxxxx
 ----------

I was wondering if anyone on these lists has much
experience with UV fluorescence photography.  I have
at my disposal about 20 UV fluorescent light tubes
(black lights), that are 15 watts each for a total of
300 watts of UV light.  Although this sounds like a
lot of light, it actually is fairly dim, unless the
object fluoresces.  How should I meter a subject lit
by UV light?  I don't think a gray card will work
because it looks very dark under UV light.  Also what
kind of films would one recommend?

Any help insight would be appreaciated.

Thanks Rolland Elliott

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