Robert Mueller <[EMAIL PROTECTED]> wrote:

Certainly if the material has appreciable sensitivity in the visible range
the user would be advised to put as much light as possible in this range,
where the optics are properly corrected.


At 01:04 02.02.03 +0000, you wrote:
> Aren't there other issues concerning the image quality that haven't been
> addressed? I can think of:
>(1) The enlarging lens must not only have the ability to transmit the UV
>radiations which are to expose the paper, it must have the ability to form
>a high quality, well-focused image in the wavelength range which is relevant.
>(2) If the photosensitive paper has any appreciable sensitivity to
>wavelengths outside the UV range, for example to wavelengths in the
>visible range, then the enlarging lens must bring these other wavelengths
>to the same focus as the UV or else the! y must be excluded from the
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Yes, I would agree that if the material had appreciable sensitivity it should be utilized. In looking at the published spectral response chart for Azo on the Kodak site one can see that the peak spectral response occurs at 350 nm and falls off from there to a marked extent by 450 nm. I anticipate communicating with Kodak this next week about the materials response in the visible spectrum. The fellow at Durst said that the light source on their new enlarger was unsuitable for conventional enlarging papers since it was heavily UV and therefore best suited for Azo and Pt-Pd. Meanwhile as an aside Michael Smith has told me that he knows of a fellow who has developed an enlarger for Azo and is in the process of obtaining patents on the device. Michael has used the equipment and finds that it produces excellent results with printing times on the order of 20 seconds. So apparently the technology is already in place the only matter is one of design. If you have further insights a! nd information, I would greatly appreciate hearing from you.

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