Compared to normal incandescent lamps, photo lamps have a significantly higher light output and a defined color temperature . Type B photo lamps with approx. 3100 to 3200 Kelvin and type A (also S ) with approx. 3400 Kelvin color temperature are common. Photo lamps are similar in design as incandescent lamps for use with or without a separate reflector or a reflector lamp in each case with an output between 250 and 1000 W . Photo lamps achieve up to twice the light output of normal household incandescent lamps with the same electrical output . Photo lamps are used with color films for artificial light , color films for daylight and, under certain circumstances, black and white films require the use of color conversion filters . Conversion filters are usually not necessary with digital cameras , as they adjust the white balance automatically or manually.
The special properties of the photo lamps are achieved by operating them with an operating voltage that is actually too high . The service life of such lamps is therefore only around ten (type A) to around one hundred hours (type B). Especially towards the end of their lifespan, photo lamps lose their light output and color quality, so that they often have to be replaced well before they die in the case of color-critical motifs.
Photo lamps are rarely used today, and the availability of such lamps on the market is correspondingly limited. On the one hand, modern halogen lamps for photographic purposes have a constant color temperature throughout the entire operating time and also last much longer; on the other hand, studio flash units have long been established in the professional sector because, among other things, they also produce considerably less heat. Even inexpensive halogen lamps ( construction lights with halogen bulb) suitable for despite the tungsten film a little too low color temperature well as a substitute for photo lamps.