16 Aug 2017

The RedShark Guide to Lens Mounts

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Index

Phil Rhodes looks at the most commonly used lens mounts in the industry, what they're used for, and what adaptation options there are for users to prevent lock-in to a technology that may not always suit their purposes.

The connection between a lens and a camera is something that ought to have been standardised decades ago, so that we could enjoy the flexibility of using any combination appropriate to the situation at hand. Of course, that didn't happen, which is what keeps companies like MTF Services in business, and because there's such a huge variety of both, it seemed like a good idea to collect together some data on the most common options, what they're used for and what adaptation options exist. Many manufacturers now offer lens ranges in various mounts, including the Veydra primes, recent Fuji zooms and even things like the Zeiss CP.2 series, making the choice of mount an opportunity for very expensive mistakes.

Mounts are interchangeable from EF to PL. The blue plastic piece is a shim for precision back focus adjustment

Mounts are interchangeable from EF to PL. The blue plastic piece is a shim for precision back focus adjustment

One note, though. Mechanical compatibility is subject to a lot of practicalities, so don't trust this data without having verified it with the particular equipment in question. Particularly, don't assume that lenses with a flange focus distance that's shorter than that of the mount can be adapted to it; some lenses, as we'll see in the entry for the PL mount, have parts which project back past the flange and can collide with camera internals. There are also many more lens mounts in existence than listed here, making it almost inevitable that some people will be interested in things not listed.

PL

Developer: Arri

Role: Motion picture

Sensor size: Super-35

Flange focus distance: 52mm

Diameter: 54mm

Cameras: Alexa, Ursa Mini PL, Moviecam series, Arriflex series, many others

Mechanism: Breech lock

Fujinon XK6x20 - PL mount

Fujinon XK6x20 - PL mount

To start with something well known, PL is the most common example of a breech lock mount where the lens is seated against a metal flange and a clamping ring rotated into place to wedge it there. This is a more precise and heavy-duty approach than the alternative bayonet mount, where the lens is inserted then rotated to push metal lugs into slots. If the lugs wear, the position of the lens can become sloppy with respect to the position of the sensor, whereas if the moving parts of a breech lock wear, they'll simply rotate a little further before clamping down hard, and the critical distances are maintained. Bayonet mounts are common in stills cameras, whereas breech locks are found on film and TV equipment.

PL is the archetypal movie camera mount. A long flange focus distance makes PL-lenses difficult to adapt to many common mounts, although the very shallow micro four-thirds and E-mounts can accept them with a simple adapter. EF-mount cameras can sometimes be reworked to take PL-lenses, although it tends to be a fairly invasive modification, involving removing the mirror and other internal components of cameras such as a Canon 7D. A minority of PL-lenses, such as the SLR Magic anamorphic, are designed without protrusions behind the flange and can be used on EF mounts with a simple adapter.

PV

Developer: Panavision

Role: Motion picture

Sensor size: Super-35

Flange focus distance: 57.15mm

Diameter: 49.5mm

Introduced:

Cameras: All Panavision 35mm models, 16mm Panavision Elaine, others with modification.

Mechanism: Breech lock

Panavision's company-specific mount is similar in its design intent to PL, with four lugs and a breech lock. It's mainly of interest to people renting from the company, although there can sometimes be a requirement to put Panavision lenses on specialist cameras and Panavision themselves convert many cameras to use their mount. Very occasionally, Panavision equipment has become available — at various degrees of legitimacy — on the open market, but sets of their widely-admired lenses are essentially a rental-only item. The E-series anamorphic lenses, famously responsible for the bold horizontal blue flare of classic action movies, are otherwise an attractive option in the modern world of digital sterility.

Adaptation, given the deep flange depth, presents much the same issues as PL. Popular interchangeable-mount cameras commonly offer a Panavision option, although again, the overwhelmingly common scenario is that of a complete, all-in-one Panavision package.

EF

Developer: Canon

Role: Stills, increasingly motion picture

Sensor size: Full-frame 35mm stills

Flange focus distance: 44mm

Diameter: 54mm

Introduced: 1987

Cameras: Full-frame Canon stills cameras; particularly, EOS-C series.

Mechanism: Bayonet

EF lens mount adaptor on JVC GY-LS300

EF lens mount adaptor on JVC GY-LS300

The EF mount was an early move toward electronic integration, completely removing any mechanical link between camera and lens. Whether that's the reason for its gigantic success is necessarily a matter for conjecture, although Canon recently celebrated shipping their 100-millionth EF-lens and so that success is hard to question. Designed for stills photography, it's a bayonet mount really intended for fairly lightweight lenses and some of Canon's higher-end motion picture glass is much too heavy to be used on an EF-mount unsupported.

EF stills lenses are frequently encountered in lower-end filmmaking because they're widely owned for stills work, because they're available at a variety of prices and because they often have a very desirable price-performance ratio, though EF stills lenses are often not great tools for moviemaking, with very short focus throw and significant breathing and ramping in zooms, though they're often very sharp. Canon's movie lenses, on the other hand, combine their excellent optics with manual controls.

It is generally difficult to adapt EF stills lenses to other cameras because there is no way of controlling even the aperture without implementing the electronic interface, for which Canon does not publish documentation. Even so, several companies have reverse-engineered the protocol and tools such as MTF's Effect lens controller can make EF-lenses usable on shallow mounts such as E and micro four-thirds. EF-mount cameras, with their deep mounts, are limited to using Pentax and Nikon lenses with simple adapters.



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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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