RE: UV photography & Tiffen makes 87 IR filter

[jason.revell@xxxxxxxxx]

For UV fluorescence photography and UV refelctography are in
some ways the opposite of each other.

UV Reflectography is the recording of the UV light reflected from
the subject which is when you use a 18A or the slightly lighter 18B.
This is as you rightly say used to show skin damage and other
forensic work.  (We are also just about to start doing it here, I am
just waiting for the filter to come!).  You can use both colour and
b+w but I believe some colour film work a lot better than others
but I am currently not sure which. (Warmer tone slide perhaps?)

UV Fluorescence is the recording of 'Fluorescence' caused when
certain substances are excited by UV light and start to emit light.
For this type of photography I would recommend the use of either
a 2E filter or a very light yellow.  What this filter actually does is
block out the UV light and only allow the 'visible' light (the
fluorescence) to be recorded.  With this type you can use any
type of film colour or b+w as you are recording the normal
wavelengths of light.  As for exposures they will depend on the
subject you are photographing, as a rough idea the Varnish
on the oil paintings we conserve the exposure is 2min @ f4.5 on
HP5+ with the 2E filter and 1min f5.6 on Elite or E100s slide film
(these being light by a total of 4 4ft BLB tubes at about 1.3mtr)

The special Nikon lens you mentioned I believe is for short-wave
UV work, as glass blocks out these wavelengths of light so the
lenses are made from a form of quartz.  As for the use of a UV
transmitting filter over the flashes may I enquire why?  This
would surely only be needed if one was not in place over the
camera lens.

If you have any further questions I can try and answer them, but
I should have more idea about this when my filter arrives!

Jason Revell
jason.revell@xxxxxxxxx


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