More Lighting
Instruments and Applications
HMI Lights
HMI lights, like ceramic lights, have several advantages over standard
quartz or incandescent lights. 
First, compared to standard incandescent lights they deliver five times the light output per watt.
This means that they generate less heat, which is an important consideration when shooting inside in a confined space. (Incidentally, HMI stands for Hydrargyrum Medium Arc-length Iodide.)
The light on the left side of this picture is a HMI light; the one on the right a standard quartz light.
Despite the difference in size, both put out the same amount of light.
The color temperature of HMI lights is the same as average sunlight -- 5,600K. This makes them an ideal fill light for on-location outside.
The standard quartz (incandescent) light
must use a blue filter to bring it up to the color temperature of
sunlight. Note the blue filter below the quartz light on the right
in the photo above. This significantly reduces the light output when
this light is used
outside.
The main disadvantage of the HMI light is the bulky and heavy, high-voltage power supply that's needed. The power supply for the HMI light at the bottom left of the photo above.)
The
back of an opened HMI Fresnel light is shown on the left.
The Fresnel lens with its circular glass rings is at the left of the picture (more on that in a second) and the HMI bulb is at the right of the picture.
Cycs (large, seamless, neutral backgrounds) can be lit from the top and bottom with cyc lights.
The one here sits on the studio floor 
and is directed up at the background.
A six-section is shown; but, depending on the area that needs to be covered, ground cyc lights can have from one to 12 sections.
The cyc light on the right is attached to the grid and is directed down along background. A large background area may require a number of these lights.
The lamps in Fresnels have been known to explode, breaking the large Fresnel lens in the front.
Since these glass lenses are heavy and they are positioned ten or more feet (3 or more meters) above the talent, this constitutes a 
major safety hazard.
The large Fresnel on the right has a wire screen in front of the Fresnel lens that is designed to keep broken glass from falling.
The use of safety cables or chains that loop from the light to the lighting grid are also important to safety.
Softlights are similar to scoops in their effect. However, instead of a large amount of direct light from the lamp hitting subjects, the illumination from softlight is all indirect.
Light from the concealed lamps is all reflected from the large reflective area. Housings can accept one or more lamps from 300 to 1,000 watts.
Open face lighting instruments are typically mounted on floor stand and used in on-location lighting. The front of these lights accepts scrims and diffusers.
These are just a few of the lighting instruments that are available for studios and on-location production. The. B&H Photo lighting catalog, for example, is almost 1,000 pages long.
