Lighting for copy photography

David Seubert <seubert [at] library__ucsb__edu> writes

>We just inherited a "new" copy stand from another department.
>Patrons use the stand to photograph/videotape items from our
>collections: book covers, photographs, manuscripts etc. It currently
>has four 150 watt Sylvania floodlights in it. This seems excessive
>and that this much light might damage some items. Does anybody have
>a suggestion or guidelines on what would be a reasonable level of
>illumination for this kind of work to minimize damage to the
>documents but not to make it too difficult to get a decent photo?
>...
>Also, we recently had a photographer ask if he should bring tungsten
>or daylight film. Assuming that most photographers are going to be
>using daylight film, should we buy daylight temperature bulbs? Has
>anybody done this? Also, is it possible to get bulbs for a copy
>stand that filter UV light?

Normally, the way to get around the daylight/tungsten light dilemma
is to use tungsten light only (normally balanced to 3200 K), and
then filter the light if daylight films are used. (With tungsten
light and daylight film a blue filter should be used).

But, the best solution for taking still photographs is to use flash
lights. They gives a very small light dose, all most no heat, and
are balanced for daylight. Correctly used flash gives a very good
lighting too, you can use multiply flash lamps, diffuser filters,
and reflector screens just as with ordinary flood lamps. However,
for the untrained it might be a good idea to have a professional
photographer to help with the installing and "tuning in" of the
system. Conservationally, flash is the correct light source.

This is of course not useful in the case of video, here a constant
light source is still needed. But having both would probably still
considerable lower the total light exposure at your collection. You
could also recommend the use of still photography in stead of video
filming.

I have never seen UV filters for photo lamps, however, I don't think
that UV is the biggest problem when using photo lighting. Not only
UV but also the visible light will cause fading. The total light
dose is just a relevant concern; how intense is the light at the
surface of the object (lux), and for how long is the exposure. And
then the heat generated by ordinary bulbs is also a major concern,
as it can dry out materials in a very short time, and cause e.g.
photographs to curl and buckle. In extreme cases (long exposures)
heat sensitive materials such as plastic can deform.

Morten Ryhl-Svendsen
Konservatorskolen (The School of Conservation)
Det Kongelige Danske Kunstakademi
Copenhagen

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                  Conservation DistList Instance 12:79
                  Distributed: Tuesday, April 6, 1999
                       Message Id: cdl-12-79-004
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