Re: Questions RE: Old, poorly stored film & B+W filter's IR

["Willem-Jan Markerink" <w.j.markerink@xxxxx>]

On 30 Jul 96 at 19:54, Cor Breukel wrote:

> >      "In general, the sensitivity of black and white infrared film is
> >      about ISO 50/18-degrees. Kodak infrared film and the B+W filter
> 
> ..sounds like gross overexposure to me: I shoot at 250 ASA, using through
> the lens metering through a dark red (+3 stops) filter, and you can start
> with even higher speeds.....

I guess they mean external meter readings....as with all
recommendations actually....seems as if no manufacturer want's to
get burned by off-spec internal meters.
BTW, in the German FotoMagazin, they once mentioned internal meter 
calibrations for several camera brands and models, based on multiple 
IR workshops. Seems as if older cameras are less off-spec than modern 
cameras, due to IR-block filters in front of AF and light meter 
cells. However, that explanation does not account for the fact that 
my EOS-1 can easily focus through a 87C filter....8-))
(I have even noticed a focus shift on my lenses....but some in the 
opposite direction as claimed by the IR mark....<sigh>....another 
mystery!)

 
> .The much quoted book of Gunter Spizing states this also, and I also
> noticed it, the Wood effect is most dramatic at dusk & dawn (these hours
> are the best very almost all photography)..

I guess the nasty blue cast and lack of shadow at noon can be 1:1
tranferred to the IR situation....blue means relatively more UV and
less IR, and shadows are known to lack IR overproportionally
compared to sunlit objects. 
Anyone care to explain the latter? All I can think of also applies to 
visible light, so that does not account for a difference....

--
Bye,

       _/      _/       _/_/_/_/_/       _/_/_/_/_/
     _/  _/  _/               _/       _/  _/  _/
     _/  _/ illem    _/     _/ an    _/  _/  _/ arkerink
                     _/_/_/  


The difference 
between men and boys
is the price of their toys

<w.j.markerink@xxxxx>
[note: 'a-one' & 'en-el'!]

------------------------------

Topic No. 16