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

[Peter Friderichsen]

Alberto,

I have posted that data as a snapshot of the graphs at 
http://www.inventionsthatwork.com/images/LeeSwatchFilters.jpg. I 
overlaid the green filter just so you can see what it looks like. The 
Lee filter website no longer shows the transmission data below 400nm 
but the swatch I have which is 10 years old (at least) does, going 
down to 300 nm.


Peter Friedrichsen



At 04:21 PM 03/13/2010, you wrote:
>Peter,
>>... the gels I cut were from a "Lee Filter"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.
>
>Have you a detailed figure of their UVA absorption? In the Lee 
>Filters site I am not abe to find any technical documentation.
>Most of the UV wavelength involving dichromate and ferric salts 
>sensitivity is in the 350-400 mn range.
>As for the Epson R2400 inks, I have published an analisys of their 
>absorption in the UVA and visible absorption.
>See http://www.albertonovo.it/scan/epson_inks.html
>Alberto
>Alberto
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