X-Rays and EIR TTL Rating

[Andy Finney <andy@xxxxxxxxxxxxxxxx>]

Hi,

In answer to questions:

X-Rays fog all film (AFAIK) because they have a very high energy. Basically
they knock particles off atoms (and more) as they go through a substance
and so can easily affect film. The effect is cumulative (which the airport
folks don't seem to realise ... at least in public) and while one pass
through a machine may not fog, eventually they will. This is unless they
can set the beam low enough to penetrate but not fog at all: is this
possible? Unfortunately air travel exposes us all to more high energy
radiation than being on the ground - especially on Concorde - and this
would also eventually fog film. Whatch out for solar flares :-)

When I used EIR I measured at 320 ISO/ASA with an orange or yellow filter
and with a one stop bracket got good results. If your camera allows
auto-bracketing you are laughing.

Regards

Andy


----------------------------------------------------------------------
+      Andy Finney: andy@xxxxxxxxxx   http://www.atsf.co.uk          +
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+       'Managing Multimedia' by Elaine England and Andy Finney      +
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