I am working on development of a light source to allow enlarging of images onto pt-pd and Azo papers. These papers need a light source in the upper UV band (350-475 nm). The other consideration are that these emulsions are markedly slower then conventional enlarging papers. I have two immediate concerns those being:
1.UV is largely invisible and this presents the problem of focusing the image on the easel. I could incorporate a conventional focusing light. If I do so will I experience focus shift when I switch to the UV lighting? Furthermore, will UV reflect in the same manner as visible light? I ask this because the light source will be diffusion to eliminate the cost of building condensors or buying a condensor enlarger since I already have three diffusion enlargers.
2. Will UV transmit through a conventional multicoated enlarger lens? I have an el-nikor 150 as my primary lens. I also have an older Schneider companon 135 mm which I think is uncoated. My Rodenstock medium format lenses are all coated.
Any information or insight that you may provide will be greatly appreciated.
