Video is often used for displaying exciting images for the artist, displaying information, or IMAG, image magnification.
IMAG is commonly created by pointing a camera at the artist and projecting that camera image much larger next to or behind them.
Video can be displayed one of two ways in a typical theater or arena show:
Projector and Screen or LED Wall.
Projectors come in a variety of shapes and sizes. Each one has one (or sometimes two) high powered lamps inside, similar to spotlight lamps. The lenses used to optimize the picture can sometimes be as expensive as the projector itself and are very fragile.
Projectors can be set up in Front-Projected or Rear-Projected depending on the type of screen and needs of the show. Some screens are opaque in the back to prevent light leakage, these can only be for front-projection. Rear-projection allows for a better presentation (i.e. the audience's doesn't have to see the projector and the artists don't have to worry about creating shadows in front the of the screen), but it allows for less overall light. Front projection is brighter, but more of a logistical challenge.
Projector screens are usually a semi-elastic plastic material that uses snaps to cover the frame. Types of frames vary, but they usually unfold and bolt together in a specific way. The screen then has to be stretched vary taut and snapped to the screen. Always use teamwork on screens, they can be very difficult.
They are typically hung in arenas using ropes and sheaves.
LED walls use an large array of small LED lights close together to create Pixels (the dots that make up a video picture). Most LED walls are put together in panels, and can range from less than a dozen panels to hundreds.
They often snap together using locks or pucks. The latter are small rectangles that attach the four corners of video walls.
Many of the good ones have internal locks that are easy to use.
Whichever the case may be, video walls are very expensive so always pay close attention and follow directions.
Cabling for video walls involves a process similar to lighting. Each wall usually gets a power and a data, and the data uses a similar path to DMX, in which each panel of the wall knows which signal to get and ignores the rest, passing the signals onto the rest of the line.
These walls are often very heavy, so they are hung from trusses and flown with motors.
Here is a short video that shows a time lapse of the set-up of a small video wall on crank winches:
Often a show will travel with its own camera operators. In this case, they may have a show call for Cable Page. The cable page follows the camera operator to make sure the cables attached to the camera are free to move. The page must feed cable out when they move forward, dress it around objects, and coil the excess when the operator moves back.
Some show calls are for local stagehands to operate cameras, and this takes some skill that can only be fine tuned by practice.
The key things to know are --
Tripod - The three-legged made to hold the camera
Frame-up - Framing up your shot means putting your subject in the center and making the angle look good for the type of show you are doing (informative or dramatic)
Pan - Turning the camera left and right
Tilt - Pointing the camera up and down
In addition to pan and tilt locks, the tripod will have Drag settings that can be adjusted to make panning and tilting smooth.
Zoom - Magnifying or De-Magnifying your shot
It is important not to zoom in tighter than necessary for a good framed-up shot; the closer you are, the more you have to move around to stay framed-up. For sporting events and other simple shows, you want to stay fairly wide to avoid losing the action.
White Balance - An adjustment to the camera setting done prior to show to ensure that white things look white and the other colors seem balanced
Focus - Adjusting the sharpness of the image
Most cameras come with auto-focus these days, but occasionally a video tech will want a camera op to use manual focus.
Sometimes a theater show will set up Infrared (IR) cameras pointing at the stage, so that backstage video monitors can see during blackouts to determine when a set change is complete. These are usually set up on the balcony rail by the video or audio departments.