Using Camera Hand Grips
The primary purpose of camera hand grips is to improve ergonomics for more comfortable shooting. Some clip onto cameras, while others are more substantial, and attach using tripod mounting screws.
Finger Loops and Leather Hand Grips
A finger loop is a small loop usually fastened to the side of a camera. Its primary use is to increase stability, especially if shooting with a heavy lens on a compact camera. If there's no suitable attachment point, it's often possible to use the camera strap lugs. A leather hand grip is similar, except that it fits around the photographer's wrist, and can thus additionally be used as a camera strap.
Improve Ergonomics With Grip Extensions
A grip extension is a fitting attached to the camera that provides additional purchase for the photographer's hands. Self-adhesive types work well with compact and mirrorless cameras that have a rectangular shape, providing increased grip and stability. More substantial grip extensions that fasten to the bottom of the camera provide extra support, especially when shooting with a telephoto lens or in portrait mode. Most have a tripod socket, and camera-specific models afford access to bottom-mounted battery and memory card slots.
Handles and Camera Pistol Grips
Handles and pistol-style grips attach to a camera's tripod socket and allow eye-level shooting using the camera's LCD screen as a viewfinder. Some types include a remote shutter switch for shooting photographs or triggering video recording.
Thumb Supports for Rangefinder, Mirrorless, and Compact Cameras
A thumb support is a lever-shaped device that slots into the camera's hot shoe. The lever is on the right-hand side of the camera in a similar position to the film advance lever on early rangefinder cameras. The purpose of this device is to provide a comfortable place to rest the thumb on Leica rangefinder cameras. You can find them, as well, on similarly shaped cameras from manufacturers such as Sony and Fujifilm.
Find the right camera grips, supports, and other photography accessories for your camera at B&H Photo and Video.