[alt-photo] Re: Alternative Exposure Unit (no pun intended)

[Peter Friderichsen]

Hi Alberto,

You bring up a good point however the gels I cut were from a "Lee 
Filter"http://www.leefilters.com lighting gel swatch. Each swatch gel 
has an attached chart of the transmission spectrum. It shows a 
transmission graph going from 300 nm up to 800 nm. I made sure that I 
chose the gels with a high degree of purity in their respective 
colour, and also that they weren't transparent to UVA.

As a further layer of protection, UVB and UVC are not a concern since 
the projector lamp won't emit at these shorter wavelengths and 
further, there some thick glass lenses that the light has to pass 
through and these will not let anything shorter than UVA to pass.

Peter Friedrichsen


At 02:39 AM 03/12/2010, you wrote:
>>I did an experiment that confirmed this. I cut up some  blue, 
>>green, yellow, and red lighting gels into squares and mounted them 
>>on a transparent sheet...
>
>I don't know if this is a good experiment. Months ago, speaking 
>about the best ink for blocking UV for negatives, at the end there 
>was a general agreement that the visible color has no correlation 
>with the opacity in the UV range.
>Alberto
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