These are usually under cut in the image area and are designed to contact only the edges or perforation area of the film. Some rollers have ridges that touch only edges of the film, or the rollers can be flat and covered with soft-touch tires for uniform film support across the roller width and to prevent scratching of the support in the image area. See Figure 59 . Access Time Two of the most widely discussed and perhaps the most misunderstood items relating to any processor are speed and access time. Speed refers to the time required for a specific point on a film to travel a specific distance and is measured in feet or meters per minute.
Access time refers to the time it takes a particular length of film to be completely processed.
Regardless of machine transport speed, which can range from 15 to hundreds of feet per minute, film cannot be processed faster than the total of the times required in each solution. For example, when a machine running Process VNF-1 is loaded and processing film, it will be 15 minutes 15 seconds before the first foot of film enters the drying cabinet no matter what the speed of the machine. However, the time for completing various lengths of film once the process times are met is in direct relation to the machine speed. With a 150-foot roll, access time will be 14 minutes 15 seconds plus 10 minutes. Each laboratory selects the appropriate development times and temperatures for the films being processed in a particular machine and with a particular formula.