usually handles that can be turned to loosen or tighten the certain axis. This allows movement in one, several, or none of the axes. When the rotation around all axes is needed, a ball head is used. There are some pan-tilt heads that use gears for precision control of each axis. This is helpful for some types of photography, such as macro photography. Other head types include the gimbal, fluid, gear, alt-azimuth, and equatorial heads. Fluid heads and gear heads move very smoothly, avoiding the jerkiness caused by the stick-slip effect found in other types of tripod heads. Gimbal heads are single-axis heads used in order to allow a balanced movement for camera and lenses. This proves useful in wildlife photography as well as in any other case where very long and heavy telephoto lenses are adopted: a gimbal head rotates a lens around its center of gravity, thus allowing for easy and smooth manipulation while tracking moving subjects. Monopod In place of or to supplement a tripod, some photographers use a one-legged telescoping stand called a monopod for convenience in setup and breakdown. A monopod requires the photographer to hold the camera in place, but because the monopod reduces the number of degrees of freedom of the camera, and also because the photographer no longer has to support the full weight of the camera, it can provide some of the same stabilization advantages as a tripod. Fixed tripods For low-angle shots particularly in cinematography, short tripods with fixed length legs and no center column may be used. The lowest of these is called a low hat, with a slightly higher version referred to as a hi hat. Travel tripods A travel tripod is one that has been designed to fit certain criteria including lightness and rigidity to give the photographer the freedom to travel and carry their tripod for extended periods. It must be small and light enough to be carried as hand baggage yet has enough strength to support a professional DSLR and fast telephoto lens. Typical specifications for a travel tripod legs would be: Weight (without head): 2 to 4 lbs (0.9 to 1.8 kg), Height (contracted): 12 to 20 inches (30 to 50 cm), Height (extended): - 60 to 70 inches (152 to 178 cm) and Max Load: 5 to 10 lbs (2.3 to 4.6 kg). See also Camera angle Close-up Long shot Low-angle shot Medium