అంబ్రెల్లాలు ముఖ్యంగా రెండు వర్గాలు:
Similar to a domestic lampshade, these reflectors are fixed to an artificial light source (for example, a filament bulb or flash tube) to direct and shape the otherwise scattered light, reflecting it off their concave inner surfaces and directing it towards the scene to be photographed. Although there are a large number of variants, the most common types are:
- spherical, short-sided, giving a relatively broad spread of light;
- parabolic, providing a tighter, parallel beam of light.
The reflector factor is the ratio of the illumination provided by a lamp fitted within a reflector to the illumination provided without any reflector fitted. A matte reflector will typically have a reflector factor of around 2, due to its more diffuse effect, while a polished or metallic-finished reflector may have a factor of up to 6.
- Focal Encyclopedia of Photography, Leslie Stroebel, Richard D. Zakia, (Focal Press, 3rd edn.) p. 689