UV photography

Marianne Weldon <mweldon<-at->brynmawr<.>edu> writes

>I would like to be able to document objects in our collection with
>UV photography but we currently are not set up to do this.  We have
>only hand-held UV lights and digital SLR cameras with no
>modifications made to them to allow for UV photography. ...
>...
>Has anyone purchased or modified equipment to do this inexpensively
>that would be willing to share their expertise? ...

For a film or digital SLR camera, UV illumination from black light
fluorescent tubes would mostly be adequate.  The closer the spectral
emissions of the tubes are confined to the 365nm of Woods Glass, the
better, but we expect a degree of visible blue leakage from
relatively inexpensive black light tubes.

To cut the blue, and filter UV light entering the lens, a yellow or
yellow-orange filter is placed over the lens.  It is best to use a
filter which does not, in itself, fluoresce; many do.  A clear UV
lens filter placed over the yellow filter will more or less stop
this, but too many filters can degrade the image.

Fluoro lights can then be used in a conventional photographic setup,
for long exposures, in a dark room.  I always wear yellow UV
filtering glasses, as otherwise I get headaches.  Long exposures,
often many minutes, can be an issue with some digital SLRs.

Among other things, I use this setup to aid image recovery with
albumen prints, writing on parchment and vellum.

James Elwing
Archives conservator
Elwing and Gurney Archival
1 Henry St
Lawson NSW Australia
+61 2 47592521


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                  Conservation DistList Instance 28:32
                 Distributed: Friday, January 16, 2015
                       Message Id: cdl-28-32-005
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