Tripod head
The main function of any tripod head is to provide the ability to hold the attached device fixed in a specific orientation until the user needs to change its position.
In the case of a photographic camera, this can help reduce vibration that would appear when using relatively slow shutter speeds while still being able to quickly recompose for another shot, or allow for very long exposures.
Heads can be attached to monopods to provide more versatility, or to a simple plate with a base mount for when the height of a full tripod is unnecessary.
Swiss camera equipment maker Arca-Swiss Phototechnik AG independently developed a quick-release mounting system for their tripod heads.
Nearly all makes and models of modern SLRs, medium format cameras, and large lenses have specific plates available with anti-rotation flanges.
Even if the clamp should loosen, the stops would limit the movement of the plate to only within the grooves, preventing a complete disconnect, and often equipment damage.
The width of the mounting plates, as well as the depth and angle of the dovetails, can introduce such incompatibilities when mixing components from different brands.
In addition to its use in photography, the Arca-type dovetail rail has also become popular in shooting competitions such as the Precision Rifle Series for attaching auxiliary equipment such as bipods, tripods, etc.
Ballheads offer the convenience of simple controls, but are lacking in terms of precise movements, making specific alignment and image positioning a challenge.
Pan heads can be used for panoramas, but suffer from the deficiency that the axes of rotation normally do not go through the entrance pupil of the lens and thus can give rise to problems with parallax.
The most important function is to rotate the camera around the entrance pupil of the lens, frequently (but inaccurately) called the nodal point.
Gimbal heads are designed mainly for long, heavy telephoto lenses, and are often used for wildlife or sports photography.
Their primary feature is the ability to balance the camera and lens within the tripod head and use tension controls to simulate a "weightlessness".
They allow for easy tracking along the vertical and horizontal axis, but generally do not offer the ability to make precise angular movements along either.
A gimbal head excels at tracking a fast moving subject, and allowing large, cumbersome camera setups to be used with more agility than nearly any other support system.
As the size of high-quality video cameras has become greatly reduced, there are now fluid heads designed even for consumer camcorders, which are being used increasingly in television production environments.
