Black-and-white slides, like their full-color companions, can be produced through the reversal process.
Rollei's R3 film is a technically advanced film that allows you to shoot at virtually any speed, and processes with nearly any standard black-and-white film processing methods. The film is designed to produce film speed in response to development, meaning that, depending on how and for how long the film is processed, you can achieve speeds from 25 to 6400 ISO/ASA. The film can also be easily processed in a reversal processes, allowing for positive black-and-white images from a variable speed film.
Reversal Process
When shooting film, there are two main kinds of images--positive and negative. Negative images from negative film are the most commonly used, producing a spectral inverse of the image photographed, which is returned to a positive image when printed with a photographic enlarger or scanned into a computer. Positive film, commonly called slide film, does the opposite, producing an exact duplicate of the image for display by projection. Producing a positive image from negative film is called reversal processing, and is the most common way to produce a black-and-white positive image for slide mounting.
How It Works
When processing negative film to produce a positive, additional steps must be taken to manipulate the film into producing a positive image from its latent negative image. The image is developed normally to expose the silver halide crystals that have reacted to the light of the original photograph. These crystals are then removed with a bleach bath and the film is exposed to white light, causing the undeveloped silver halide crystals to react. The film is then developed normally, producing a positive version of the image negative image.
Advantages
Specially designed for the reversal process, Rollei R3 film has a durable top coat over the film, called a supercoat, that allows the film to withstand the bleaching phase commonly used in the reversal process. Furthermore, the base of the film is clear rather than gray, like most black-and-white films. While this was originally developed to allow R3 film to replace glass plates, it also makes the film especially suitable for reversal processing, as the gray base layer does not interfere with projection.
R3 Film Speed
R3 film can be processed to be extremely fast, making it an excellent choice for black-and-white slide production. Most films that are dedicated for positive black-and-white slide projection are extremely slow, making it difficult if not impossible to create satisfactory images in less-than-satisfactory lighting conditions, making such film best suited to the studio. R3 film, on the other hand, can produce satisfactory images at speeds as high as 6400 ISO/ASA and still be successfully processed through the reversal process, producing reliably sharp and clear images even in low-light situations.
Tags: positive image, negative film, reversal process, black-and-white slide, commonly used