Mounting methods – Joining camera and lens

In cameras with removable lenses there are two basic methods of attaching a lens to the camera body. With some minor variations these two approaches cover almost every camera available today.

The oldest and simplest device is the screw thread mount. The end of the lens barrel is threaded like a water pipe. It screws into a similarly threaded flange on the camera body so that when the lens is turned as far into the flange as it will go, the fit is snug and secure, and all the scales and numbers are on top where they can be easily seen.

The screw thread mount has several advantages. Besides being reliable and free from adjustment problems, it allows a camera owner to buy lenses from an amazing variety of sources. Thread pitch, along with a few of the most practical lens barrel diameters, has been standardized so that hundreds of lenses from many different manufacturers are available to photographers with screw mount cameras.

Unfortunately, the screw thread mount has one big drawback – the time it takes to interchange lenses. Removing the first lens involves turning it several rotations until it clears the flange. The new lens then has to go through similar procedure in reverse.

To speed up the changing of lenses on smaller cameras, the bayonet mount was introduced. A savings of time and effort over the screw thread system is the bayonet mount’s greatest advantage, resulting in its present popularity among both lens manufacturers and users.

The breech lock mount is a variation of the bayonet mount. Instead of twisting the lens into place after alignment and insertion into the camera body, a movable flange on the lens barrel rotates a quarter turn to make the connection secure.

The “T” mount adapter system is another approach. Each T mount lens is furnished in a standard screw mount which is a little too short. However, when coupled with a special adapter, each lens becomes exactly the right length. The advantage is not the speed of interchanging lenses; it is the fact that a photographer can purchase one T mount lens and use it on many different cameras just by acquiring the proper adapters.

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