18A UV pass filter for studio strobe lights

[Rolland Elliott <rolland_elliott@xxxxxxxxx>]

Hello all you UV fans,

I just got three glass circular five inch diameter 18A
UV pass filters in the mail today from UVP
(Ultra-Violet Products).  These filters only alow UV
light and IR light to pass through them and block all
visible light.  Cost was only $27 dollars each!   This
company makes a whole array of products that some of
you might be interested.  They have a great web site
at www.uvp.com.  

I'm going to use these filters over a Quantum X2
strobe, and two Lumedyne portable strobes I have for
UV photography. With a little black electrical tape
these filters fit perfectly over the strobe
reflectors. Since many strobe reflectors have about a
5 inch diameter opening they could probably be taped
on to a wide variety of strobes.  The filters are
domed shaped and made of thick glass (about 8mm
thick!)  so they probably wouldn't be good for
mounting over a  camera lens.  They might also be good
as a filter for IR surveliance photography since there
is only a dim purpleish red glow from them when the
strobe fires.  Sorry don't know the specific
wavelengths they pass.

With any luck I'll be able to get shorter exposure
times using strobes.  For my first try with UV
photograhy I used a B+W 403 UV pass filter with
several lenses (a Nikkor 300mm f/4, 20-35 f/2.8
Tokina, & 70-210 f/2.8 Sigma) along with Fuji RTP
Tungsten 64ISO film.   My intial results were
horrible.  Most of the pictures didn't even turn out. 
The few that did had exposure times of two to eight
minutes at f/11. (in bright midday sunlight)  And
these images were  only one color, a navy blue.  Seems
like I could have gotten similar images by using a
deep blue filter over any camera lens.  

For my second attempt I used the same lenses and Kodak
Color IR film rated at ISO200. This time I used the
B+W 403 UV pass filter and a blue/green IR blocking
filter made by B+W.  The resulting images were awful. 
It appears that the blue/green IR blocking filter
doesn't do a very good job since most of my images
were totally red with some purple highlights. 

I few weeks ago I posted that I would be trying to use
old EL Nikkor enlarging lenses for UV photograhy since
Nikon claims they are corrected for UV light down to
350nm.  I just ordered an old Nikon III bellows and a
Nikon adapter that goes from Nikon's F-mount to a 39mm
thread (nikon makes this adapter). This will allow me
to easily mount and focus the enlarging lenses on my
Nikon camera. I'll also have to order a B+W 39mm 403
UV filter since handholding a larger filter infront of
a lens doesn't work when the exposures are more than a
second.

Hopefully I'll figgure a way to take great UV pictures
without spending $3,000 dollars on Nikon's UV 105
f/4.5 lens.

I'd like to hear from other UV photographers and what 
kind of equipment they use for UV photography as well.

Peace Rolland Elliott


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