Re: 18A UV pass filter for studio strobe lights

[Rolland Elliott <rolland_elliott@xxxxxxxxx>]

I wrote:  "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."

To which Andrew Davidhazy Responded:
"This is to be expected. The UV filter blocks all
visible but allows UVto pass.This exposes the top
layer on your film. Since you do not have green or red
passing through the filter obviously you will not get
any colors other than blue."

I don't think you are correct.  Take a look at the
following web site:
http://hawk.foto.no/pinhole/nikon/index.html
The photographer, Bjørn Rørslett, uses a Nikkor 105 mm
UV lens with a Nikkon 18A filter and gets three
distinct colors in his pictures: red,  blue and white
using reflective UV photography techniques.  If he can
do it, why can't I?

Andrew also wrote:
"For spectacular results I would concentrate on UV
excited fluorescencephotographs. This you can do on
regular color film. For spectacular color IR
photography you need only a deep yellow filter over
the camera lens to removethe blue to which all three
layers are sensitive."

Thanks for the tips Andrew.  I think I'll give UV
fluorescense photography a shot!

WJ also responded to my message saying:
"UV-reflective photography means recording patterns on
film which are invisible to thehuman eye, and this
requires an UV-sensitive film....but *because*you are
recording UV-only in this case, all you can expect is
amonochromatic image (b&w or color)....unless you can
find a film that has more than one layer of (final)
color, sensitive to smalldifferences in UV (say
360-380nm creates blue, 380-400 createsgreen, and
400-420nm creates red)....but AFAIK, such films
don'texist, it's all monochromatic in this range."

My responses:  WJ, have looked at the following Web
site I mentioned above
(http://hawk.foto.no/pinhole/nikon/index.html)?  This
site clearly shows UV color photographs that have red
blue and white colors in them and are deffinetely not
monochromatic.  The only explanation I can think of is
that the Nikon 18A equivalent filter allows UV light
and some red light to pass through it.  Therefore the
pictures on this web site are not "pure UV
photographs" because they are formed by UV light AND
red visible light. Does this sound right to you?

Thanks Rolland Elliott


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