04 Feb 2018

The RedShark Guide to Lens Mounts

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Developer: Canon

Role: Small-sensor stills

Sensor size: APS-C

Flange focus distance: 44mm

Diameter: 54mm

Introduced: 2003

Cameras: APS-C Canon stills cameras

Mechanism: Bayonet

EF-S is essentially identical to EF, though with the stipulation of a smaller sensor. As such, a great deal of the DSLR video that's been shot since the introduction of video has actually been behind an EF-S mount, although the compatibility of full-sized EF-lenses means that either can be used on Canon's small chip cameras or any of the many others which have adopted the mount.

The selection of lenses in EF-S mount is much more limited than in the full-size mount, although there's at least one star — the 60mm f/2.8 USM macro prime, which is sufficiently good that we felt able to apply a Gear We Like award back in 2013. Adaptation concerns are essentially the same as for EF, with some concern that lenses intended to cover full-frame 35mm stills sensors may over-project the sensor and send light bouncing around inside the lens cavity, creating flares. Most EF-equipped cameras are set up to deal with this, with baffling and non-reflective finishes inside the mount.


Developer: Canon

Role: Small-sensor stills

Sensor size: APS-C

Flange focus distance: 18mm

Diameter: 47mm

Introduced: 2012

Cameras: Canon mirrorless cameras

Mechanism: Bayonet

The latest addition to Canon's mount lineup is essentially EF modified for mirrorless cameras. With a sensor — in effect — permanently in live view, an electronic viewfinder can be used, much as with micro four-thirds. The attraction for camera manufacturers is that the electronic viewfinder is much cheaper to mass-produce than the complex mechanical and optical parts of a conventional mirror viewfinder, and the resulting camera can be smaller. The mount is mechanically similar to EF, albeit slightly smaller.

EF-M is included here for completeness. No popular video camera has yet adopted it. It does more or less the same job as Sony's E or micro four-thirds, and EF-M lenses are generally those intended for the very smallest interchangeable-lens cameras.


Developer: Canon

Role: 35mm stills

Sensor size: Full-frame 35mm

Flange focus distance: 48mm

Diameter: 42mm

Introduced: 1971

Cameras: Canon F-1 etc.

Mechanism: Bayonet

Canon's FD is the mount that EF essentially replaced and in the process effectively obsoleted, at least temporarily, a lot of very well-regarded glass. Because FD is deeper than EF, a simple adaptation has never been possible and for a time FD-lenses became very affordable. Now that there are a lot of cameras around with very shallow mounts and adapters with optical elements to adjust for the physical spacing issue, the value of famous old FD lenses has grown to the point where they're no longer such a steal. The FD 50mm f/1.2L tends to go for over $600 and is just one of a whole galaxy of FD-lenses on eBay, although the FD 24mm f/2.8 SSC tends to be under $200 and represents an interesting wide-angle option. Any of them can be adapted to E or micro four-thirds.

It's likely that there has never been and never will be a digital camera with an FD-mount. Such a thing would be an entertaining historical curiosity, though, so if anybody's ever seen one, let us know.


Developer: Sony

Role: Mirrorless stills cameras

Sensor size: Varies; up to full-frame 35mm

Flange focus distance: 18mm

Diameter: 46mm

Introduced: 2010

Cameras: NEX and ILCE series

Mechanism: Bayonet; breech lock on FS7 Mk. II

E-mount showing filters

E-mount showing filters

It's possible to see the E-mount as essentially Sony's response to the Olympus-Panasonic collaboration that led to micro four-thirds. It is the shallowest of any mount we're discussing, placing the reference plane of the lens a mere 18mm from the sensor and as such adaptable to essentially anything, including MFT. This is clearly at least part of the intention and as such it's tempting to assume that lenses available in E-mount might not be that interesting. In fact, some important zooms have been released in the format, including the 28-135mm f/4 and 18-105mm f/4 which, among others, have been paired particularly with NEX-series cameras. They're not high-end lenses, being electronically controlled, but the combination of range and price makes them hard to beat on highly-mobile, cost-constrained productions.

The E-mount is important to cinematography principally because of its presence on the FS series video cameras, including FS5, FS7 and FS700, which represent some of Sony's most important products in that field. Of particular interest is the FS7 Mk. II, which essentially reimplements the E-mount as a much tougher breech-locking design. E-mount lenses can only ever fit E-mount cameras, but E-mount cameras can be adapted to take essentially anything.


Phil Rhodes

Phil Rhodes is a Cinematographer, Technologist, Writer and above all Communicator. Never afraid to speak his mind, and always worth listening to, he's a frequent contributor to RedShark.

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