Thanks for bringing those issues to bear. I think that you have a valid concern. However in looking at the spectral response on the Kodak Azo data sheet it does show a marked decrease at the 450-475 nm level. I do expose Azo (contact print) with the use of a 300 watt R40 flood. I do not have the spectral range of that lamp but it must carry some UV as part of its output. I do know that Durst Pro is bringing out a 5X7 enlarger in March that will be used only for purposes of Azo and Pt-Pd. I spoke with them yesterday and they stated that while they did not advertise a wattage output of their lightsource of that enlarger since being heavily UV in output that wattage did not directly apply. I do not know enough about light intensity measurement in the UV spectrum to understand why wattage would not be determiner. Their representative after stating wattage was not advertised did say that it would be the equivalent of a 1000 watt source. Obviously a enlarging lens would need to! focus that light onto either Pt-pd or Azo paper. If you have further knowledge about this that would be of benefit, I would certainly appreciate hearing from you about it. Thanks again.
Robert Stoddard <[EMAIL PROTECTED]> 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 they must be excluded from the illumination.
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