Often, a tripod is sold with a head as a single item, but with more upmarket tripods the legs and head are usually sold separately so that you can choose which you want to use. There is a universal 3/8-inch screw attachment used on tripods and heads so that as a rule you can fit any tripod head to any tripod.
Ball heads are smaller, lighter and often cheaper than three way heads. They operate on a simple principle – the camera is attached to a ball which sits in a socket. You release a locking screw to allow the ball (and the camera) to move in any direction, then tighten the locking screw to fix it in that position.
More advanced ball heads have a larger payload (weight capacity) and come with additional controls. Many have a separate pan axis so that you can turn the camera horizontally without otherwise affect its angle. This is useful for panoramas or panning shots, where you don’t want free movement in every direction.
Some ball heads also have friction controls, so that when you release the locking knob, there is still some resistance in the movement and the camera doesn’t instantly ‘flop’. This helps with precise positioning too.
Three way heads
Despite the controls on more advanced ball heads, they still don’t offer the precision and positioning accuracy of a three way head. Here, the head offers three axes of movement, including a pan axis, a tilt axis and a third axis usually used for rotating the camera through 90 degrees for vertical shots.
These are sometimes called ‘pan and tilt’ heads but it’s more accurate to call them three way heads. You can also get specially designed video heads, however, which don’t have that third axis of rotation (you don’t shoot video in a vertical format, only horizontal).
Three way heads can have their own adaptations for particular areas of photography. Videographers will often pick a ‘fluid head’ that uses smooth-turning fluid capsules instead of regular bearings. These give much smoother and more controllable manual camera movements while filming.
Landscape and architectural photographers may use a ‘panoramic head’ designed specifically for taking overlapping images for stitching together into a seamless panorama on a computer. Panoramic heads have scales on the pan axis to measure the angle of rotation for a consistent overlap, and specially designed camera plates that let you slide the camera forward and back to get its optical center (nodal point) directly over the axis of rotation – this helps eliminate parallax shifts with nearby objects.
Close-up, nature and macro photographers will often use a geared head for more precise positioning. Instead of releasing a handle and turning the camera manually, you turn a knob linked to a screw drive to move the camera in much smaller and more precise increments.
Quick release plates
On basic tripod heads, you simply screw the camera on directly. Most tripod heads, however, use a quick release plate. You screw this into the base of the camera and then clip the plate (and camera) on to the tripod head. Once the plate is attached to the camera, it’s much quicker to attach and remove it from the tripod to swap quickly between tripod and handheld shooting.
Different makers use different quick release plate design. Manfrotto, for example, uses a proprietary QR plate design. However, many tripod and tripod head makers use a more or less standardised Arca Swiss design. Arca Swiss is a high-end camera maker whose quick release plate design has been adopted widely by others.