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
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