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  1. #11
    Jorge Oliveira's Avatar
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    From the sensivity curves of enlarging paper, a near UV light will be Ok with them.
    While AZO is most sensitive to near UV, other papers are about flat from blue to near UV.
    But this is for graded - VC may become grade 5.5!

    Lenses may be trickier, some will block near UV.

    Jorge O
    Curitiba - nice place to live, if you don't care about the weather...

  2. #12

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    There are a number of factors that will impact on the operation of this light source. The first being that the greatest amount of experience to this point has been in contact printing of negatives with the "blue" portion of the visible light spectrum. This is what is exposing Azo when we use the reflector flood lamps. Thus negatives have been developed for this exposure spectrum.

    The UV light source will change things for those who are using staining developers. The effects of this proportional stain will become more pronounced with certain developers when using the UV light source for exposure. The stain presents itself as greater density to UV transmission then it does to blue light transmission. In the negative density range that we normally use on Azo the effect of UV transmission can make a lot of difference insofar as the contrast on the print.

    I believe that Michael Smith addressed this fact in one of his recent posts. Either here or on the Azo forum (I forget which).

    The other thing that is going to become increasingly important is exposing and developing the negative more precisely. Excessive density will become the problem that it has long been for alt process printers. For that reason I think that to effectively use the potential of this light source film speed tests and camera negative density tests will be beneficial. To make welding goggle negatives will be a problem. I don't think that DBI will produce the results indicative of the potential that this light possesses.

    Insofar as enlarging lenses. El Nikkor lenses will pass about a stop more UV light then comparable Schneider Componon and Rodenstock Rodagon lenses. This information comes from the inventor of this light source and also from Jens at Jensen Optical/Durst Pro. This is an important consideration as Jorge mentioned. There are probably another lens design or two that will work. I have heard of some really expensive quartz glass enlarging lenses that work too.

    My first thought is that a negative developed to proper density range for grade two enlarging with pyrocat developer will probably be fairly near what is required for grade three Azo. However tests will need to be done to confirm this.

  3. #13

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    Developing by Inspection can give you any kind of negatives you want. I do not understand your comments that it would not give you suitable neagtives for enlarging with this light onto Azo.

    You can use DBI for any negatives--even 35mm roll film. Many of the old-time photographers did it that way.

  4. #14

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    I beleive what Don is trying to say is that spped and developing tests will have to be more accurate for use with the UV light than with the regular azo/light bulb combination.

    I agree with him, measuring UV vs transmitted light (blue channel) can mean as much as a stop and a half in absorbption, with the concurrent increase in b+f absorbtion.

    If roll film is to be used to be enlarged onto azo, I feel accurate film speed and developing test will be of great value. While DBI is an useful tool, I dont think it is the best choice for negatives to be enlarged, specially with ABC.

  5. #15

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    Jorge,

    Thank you. That is what I was saying...perhaps too wordy in my explanation. I have used DBI and for the life of me I can not tell within .15 log units of density what the negative density is when examined with the green light. Perhaps I am not as adept as some of the practitioners of DBI and I will give that possibility. To be honest I can not tell within .15 log units of density in bright room light when I get up into the 1.85 area especially when considerations of proportional stain and different light sources enter the equation. I guess that I am not alone in that inability.

    I think that we all want this light to produce a good result for purchasers and potential purchasers. I think that to do that the information that will enable those good results would be beneficial. This information may possibly indicate a departure from established methods. I gathered from the inventor a real awareness of density requirements for this light to work to it's full potential. I also heard his concern about over exposed and overdeveloped negatives. I fully concur with his thoughts on that matter.

  6. #16
    Jorge Oliveira's Avatar
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    At the time the semiconductor industry used UV lithography, there were lenses specially designed for it, all made of quartz.

    If one is lucky enough to find one of these used, they are wonderful glass (for UV).

    Jorge O
    Curitiba - nice place to live, if you don't care about the weather...

  7. #17

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    It seems that enlarging on AZO and contact printing on AZO will require different types of negatives - i.e. for the former less dense (am I assuming correctly?). If this is indeed the case then a comparison of print quality between, for example, an enlargement onto 8x10 AZO and an AZO contact print of an 8x10 negative should result in one being superior to the other, at least in terms of tonal values, shadows, highlight separation etc. I find it unlikely that we shall find equivalence in quality between the two BUT I eagerly await the results.
    Francesco

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