A lens adapter is a device to mount lenses made for some type of camera on another camera for which they were not originally designed.
An adapter will receive any lens with a given type of lens mount, and attach it to a camera body with another lens mount. In some cases the use of a lens on an adapter changes the distance range or the speed of the lens.
above: 1. M42 thread in Four-Thirds bayonet
2. M42 thread in Minolta SR bayonet
3. M42 thread in Minolta AF bayonet
below: 1. M39 thread in M42 thread
2. Minolta SR bayonet in Four-Thirds bayonet
3. Exakta bayonet in Minolta SR bayonet
image by Uwe Kulick (Image rights)
Adapters for autofocus lenses
The type of adapters mentioned above is common, to adapt lenses with manual focusing and manual aperture control; but adapters may be available for some modern lenses with electronic systems too.
The main efforts to support full automatic functionality of adapted autofocus lenses were made by the surviving big players in the camera market when they launched their CSC cameras. Most of them created own adapters including electronic translation units for the signals between camera and lens. These devices usually connect the lenses of an older SLR or DSLR system to the newer CSCs of the same camera maker. Thus the new camera types soon become popular among the brand's old fans since their old lenses work with full functionality on the hottest new digital system cameras.
Only a few independent efforts were made by accessory makers, some even to achieve inter-brand adaption of autofocus lenses. Metabones is one maker of such adapters. It offers adapters to mount Canon EF lenses to Sony E-mount, and others to attach them to Micro Four Thirds cameras, both adapters supporting electronic aperture control by means of the camera mount's original lens control signal protocol. The adapter variant for the E-mount even supports electrical focusing for many Canon lenses made since 2006, but according to Metabones`own product description that solution works slowly. To reach more buyers with that limited solution the adapters are also available as wide-angle converters with optics which boost an attached lens's speed significantly. Metabones calls these converter adapters "speed booster".
- Metabones Speed Booster
- Metabones Smart Adapter
- Sony - 4 types of the adapter LA-EAn are available to attach old Minolta AF lenses or similar Sony lenses to CSCs with Sony E-mount like the Sony NEX
- Olympus MMF-1 adapter to attach Four-Thirds lenses to Micro Four-Thirds bayonets of Olympus` and Panasonic`s CSCs
- Canon Mount Adapter EF-EOS M to use Canon EF lenses on the Canon EOS M CSC bodies
- Nikon bayonet adapter FT1 for Nikkor lenses with F-mount on Nikon 1 system cameras