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A positive form negative
"piterengel" wrote in message ... Hi everybody. I need for a certain work to obtain some positives from negatives. I can't treat all film with positive method, because a part of photos must remain negatives. I have a Contax Auto PC Bellow with slide duplicator, and a RTS II camera. Photos are taken using an Ilford Delta 100 film, developed in ID11. I want to use the same film for positives. My questions a - can I find somewhere a manual for PC Bellows? - Is it better to use natural light of TTL flash light to make positives? Thanks all for the help. Ziocalepino There are several ways to do this. If you are working in B&W (and it appears you are) you can scan the negatives and make positives using a printer similar to the way enlarged negatives are made for alternative processes printing. You can enlarge onto slow film using an enlarger with some attenuation of the light, or you can copy using a view camera and illuminator for the negative. For same size transparencies you can contact print. Unfortunately, the best film for B&W postives, Kodak Fine-Grain Release Positive, is no longer made in any size other than 35mm. However a number of slow films will do OK provided you can adjust the exposing light. If the positives are for direct viewing or projection they must be of rather high contrast and have high black density. 100T-Max and Delta 100 are good for this since both can reach quite high Dmax and high contrast. You will probably want to use a developer like D-19 or Dektol. I am not sure if there is any data for such use of these films so you will have to experiment to find the correct exposure and development times. For positives for direct viewing the development will be similar to print development, that is to "completion" or to the highest Dmax the film is capable of. Some variation is possible to adjust the contrast to match the negative. For making same size positives just use a glass sandwich and contact print. Leitz used to make a neat little contact printer for just this purpose. The only problem with printing onto panchromatic film is that you can't use a safelight. I think Ilford makes an orthochromatic film which would allow the use of a red safelight. Note also that nearly all B&W negative 35mm films have some pigment in the support which is not removable or bleachable. This reduces the brightness of slides a bit but unless you have other slides which are on a clear base no one will notice. -- -- Richard Knoppow Los Angeles, CA, USA |
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