Light Boxes And Illuminators
Useful Accessories For Every Photographer
Most devoted photographers will have several different types and sizes of light boxes for use in a variety of situations. Possibly the most common use for a smaller, basic light box is in the darkroom to evaluate a negative or transparency prior to placing it into an enlarger. My Kreonite enlarging station has one built into the base, making it quick and easy to check the orientation of the negative and to look for lint or dust prior to placing it into the negative carrier. For this type of usage most any size of light box is adequate and you don't need special color-corrected illumination.
Utilitarian light boxes come in a wide variety of sizes and exterior configurations. Most AC-powered units are flat and 2-4" or more thick so that they will lie on most any tabletop for viewing from above. Most include some type of leg or brace that can be folded out to prop the box up inclined at an angle. A few have a handle for easier carrying to another location. You can even get battery-powered portable light boxes from 4x5" up to 8x10" for use most anywhere.
A few light boxes, like the Logan "Slim Edge" Light Pad are ultra-thin (only 1/2" thick) while still providing even, bright illumination across the entire 8x10" viewing surface. It has two 5400K color-corrected lamps with a 20,000 hour life. In addition to conventional tabletop use it's suitable for wall use or as a standing vertical display unit. Alternatively, it can be easily stored in a desk drawer or carried in a briefcase. In addition, 4x5", 5x7", and 11.5x16" versions are also available.
Another type of basic light box is the slide sorter with many rows of molded-in shelves that can hold dozens and dozens of mounted 35mm slides when you are arranging them prior to placing them into a slide projection tray for a presentation. These units usually have a standard incandescent light bulb inside, a reflector to spread the light relatively even, and a plastic or acrylic translucent white front to further diffuse the light. They may not be color corrected, but all provide a convenient method of viewing the images on a large number of mounted color slides.
Critical Color Evaluation
For critical color evaluation of transparencies, ad agencies, color labs, and printing production houses have certain standard procedures that must be followed for reliability and critical dependability. As a fluorescent lamp warms up there is a significant change in color balance and light output. Initially, when first switched on, the color quality is "cool" plus the light intensity is slightly low. It takes about 20 minutes "on" time for thermal equilibrium and stabilization of both the color balance and light intensity. Any extra-critical color balance evaluations should not be attempted until this basic warm-up is complete.
In addition, fluorescent lamps age with use and the phosphors shift in both color balance and output, resulting in light quality that is progressively "yellower" and less intense. After approximately 2500 hours of use, the light emitted from the lamp will no longer meet the standard D50 and should be replaced. Some professional firms will have a timer connected to their illuminators to keep track of the "on" time just for this purpose.
Typical illuminator sizes (in order of popularity, according to Hall Productions) are 12x18", 10x12", and 18x24". The advantage of having a larger light box is the viewing surface will accommodate more than one project at one time.
Prices vary widely. A 4x5" portable, non-color-corrected unit lists for under $30. Many makes of 8x10", metal-framed illuminators with color-corrected 5000K lamps sell for $50-$100. Handsome wooden-framed units list for $200 and up. There definitely is a light box or illuminator to suit any need or budget. A few of the firms that manufacture or distribute these units are listed below. They will provide information on their products upon request.