lens mount by pratik
Apr 21, 2018 Written by Pratik srivastava lens mount
Type of mount
1-A lens mount may be a screw-threaded type, a bayonet-type, or a breech-lock (friction lock) type. Modern still camera lens mounts are of the bayonet type, because the bayonet mechanism precisely aligns mechanical and electrical features between lens and body.
2-The axial adjustment range for focusing Ultra wide angle lenses and some Wide-angle lenses in large format cameras is usually very small.
So some manufacturers (e.g. Linhof) offered special focusing lens mounts, so-called wide-angle focusing accessories for their cameras. With such a device, the lens could be focused precisely without moving the entire front standard.
3-Secondary lens refers to a multi-element lens mounted either in front of a camera's primary lens, or in between the camera body and the primary lens.
4-(D)SLR camera & interchangeable-lens manufacturers offer lens accessories likeextension tubes and secondary lenses like teleconverters, which mount in between the camera body and the primary lens, both using and providing a primary lens mount. Various lensmakers also offer optical accessories that mount in front of the lens; these may include wide-angle, telephoto, fisheye, and close-up or macro adapters
5-Lens mount adapters are designed to attach a lens to a camera body with non-matching mounts. Generally, a lens can be easily adapted to a camera body with a smaller flange focal distance by simply adding space between the camera and the lens. When attempting to adapt a lens to a camera body with a larger flange focal distance, the adapter must include a secondary lens in order to compensate. This has the side effect of decreasing the amount of light that reaches the sensor, as well as adding a crop factor to the lens. Without the secondary lens, these adapters will function as an extension tube and will not be able to focus to infinity
6-With this basic concept in mind, lens adapters can also be substantially more sophisticated and maintain electronic communication between the adapted lens and body through the use of dandelion chips, with some adapters even capable of retaining a lens’s autofocus and image-stabilization capabilities.
7-- CANON: The FD mount fits all manual focus Canons from 1970 forward; the EF mount fits all EOS series autofocus models. These mounts are NOT interchangeable; adapters are available but I would avoid them. Canon EOS film and digital SLRs can, on the other hand, accept almost anything BUT a Canon FD lens with adapters: Nikon, OM, Pentax M42 Screw, and Leica SLR lenses can all be adapted.
The EF-S mount ('S' for short back focus) uses the same mount distance, but is specified for cameras with smaller mirrors and sensors, allowing the back of the lens to protrude into the camera body more than the standard EF mount.
9-EF lenses can be used on an EF-S body camera, but not vice versa.
10-The EF lens specifications include a requirement for the image circle of the lens to cover at least 43.2mm, so as to cover the full size 36x24mm sensor. With EF-S this is reduced to cover Canon's version of APS-C (~22.5mmx15mm) or a 27.3mm image circle