Black and White Slides from Black and White Negatives
By Ken Smith. (Area 4).
There are times when black and white slides can prove to be very useful, either on their own or as part of a colour slide show. Occasionally it is an advantage to remove all colour in order to concentrate attention on light and shade.
Most members will be aware of the reversal process for making black and white slides from orignal material but there are times when the ideal subjects are available only in the form of black and white negatives. On these occasions it can be very useful to produce positive slides from such negatives. Recently I had such an experience and maybe my findings coud be of interest to others.
An ideal film for making black and white slides is Kodak technical pan 2415 and after tests I have found the optimum speed rating to be ISO 200 when the film is deveIoped in Kodak d19b developer with four inversions every thirty seconds.
This film and processing combination will increase the contrast of a normal negative having a gamma of 0.55 to give a full range of tones from pure white to intense black in the projected slide.
The copying procedure can be contact, but projection will allow control over framing and the degree of magnification. Using a friend`s `Illumitran` I have had excellent results but not everybody has access to such a device. Almost equal results can be obtained by using an enlarger to project the negative image onto the film loaded into an SLR camera with the lens removed. The focusing is achieved on the enlarger whilst framing and magnification are controlled by altering the position of the camera. Exposure is controlled by the camera shutter (for ISO 200 I use 1/60th sec.) and the aperture on the enlarger lens. It is best to bracket between F8 and F11.
In addition to copying negatives as slides the process is useful for making reverse text slides. Black and white originals such as text on diagrams can be photographed on Technical Pan film ratd at ISO 200 and processed as above to produce slides with white text on line and an intense black background.
Anyone interested in further technical information about Technical Pan film can obrtain leaflet No. P.255 from Kodak.
