Films used for copying are processed the same as any other film. They can be processed by machine or by hand, using tanks or trays. Recommendations for specific developers, developing times, and developing temperatures are given with each type of film. Some films not designed specifically for copying may yield negatives with excessive contrast. This can usually be avoided by reducing the developing time. Consult the Photo-Lab Index to find suitable developing times to lower or raise contrast.

CATHODE-RAY TUBES

Although taking photographic images from cathode-ray tubes (CRT) is not actually a type of copy work, it has become more commonplace to photograph their images for briefs and presentations. Televisions, computer monitors, and radarscopes all can be classified as CRT photography.

When you are shooting CRTs, like all copy photography, it is important for the optical axis of the lens to be centered and perpendicular to the monitor. The camera must be mounted on a sturdy tripod. A cable release and a macro lens are recommended.

When you are photographing radarscopes, time or shutter speed is not a factor of exposure. The number of sweeps on the scope is the factor that determines the exposure at a given f/stop. The number of rotations is not proportional to film exposure. As a general rule, the exposure doubles between one and three sweeps. To get the correct exposure, you must bracket the exposure. A good starting point for less than three sweeps with ISO 125 film is at f/5.6.

To get the sharpest and clearest image possible, you must adjust the brightness of the radarscope correctly. Do this by turning up the intensity until halos appear. Then turn it down until the halos just disappear. When the intensity of the scope is too great, the image appears out of focus. If the intensity of the scope is not great enough, there is little contrast between the video and the background.

Computer-generated graphics are a common means of producing material for use in slide briefings. When available, use a computer monitor with a flat screen rather than a curved screen Use the same procedures for shooting computer screens that you use for radarscopes. The difference is there is no sweeping motion when shooting a computer monitor or a television. When motion is apparent, you must use a shutter speed of 1/30th of a second. When you use this shutter speed, the film records the image without obvious scan lines and stops the motion of the image.

When photographing images from a CRT, always darken the room before you make the exposures. This prevents glare on the screen and only the illumination from the screen affects the film.

SLIDE DUPLICATING

In photography, you must often make duplicate slides from an original. Duplicating is actually a form of copying. A duplicate or dupe can be made to almost any desired size. Contrast and density along with color adjustments can be made when duplicating color slides.

Color slides are duped to provide extra copies of the slide, correct color balance and contrast errors, or even to change or enhance colors for special applications.