04 Feb 2018

The RedShark Guide to Lens Mounts

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Index

Micro four-thirds (MFT)

Developer: Olympus and Panasonic

Role: Mirrorless stills cameras

Sensor size: Four thirds

Flange focus distance:19.25mm

Diameter: 38mm

Introduced: 2008

Cameras: Lumix DMC-G1, GH series

Mechanism: Bayonet

The “micro” prefix indicates the purpose of this popular mount: the full-size four-thirds mount is designed to accommodate a mirror box much like a conventional Nikon or Canon DSLR. Perhaps because of the state of technology at the time of its launch, the mirrorless micro-version has become better known and has even been chosen to serve some cameras using a super-35mm sensor, including some Blackmagic products and the JVC GY-LS300. As the name suggests, the mount was designed for sensors four-thirds of an inch diagonally and has a relatively limited diameter which demands careful engineering for proper coverage of super-35 sensors.

Veydra have made lenses to suit micro-four-thirds mounts, but because the mount is so shallow, it's generally impossible to use them on other types.jpg

Veydra have made lenses to suit micro-four-thirds mounts, but because the mount is so shallow, it's generally impossible to use them on other types

Lenses native to the mount are mainly intended for stills work, though many purveyors of the more affordable end of cinema lenses offer micro four-thirds mount. If there's a deeper alternative available, buying lenses in MFT can be rather limiting because they can only ever go on MFT or E. Conversely, an MFT camera can accept anything other than E-mount lenses.

FZ

Developer: Sony

Role: Film and video

Sensor size: 35mm full frame

Flange focus distance: 19mm

Diameter:

Introduced: 2011

Cameras: Sony Cine-Alta series

Mechanism: Breech lock

This is a Nikon mount adaptor to suit Sony's FZ mount. The enormous size of the FZ mount is clear in comparison.jpg

This is a Nikon mount adaptor to suit Sony's FZ mount. The enormous size of the FZ mount is clear in comparison

The enormous FZ-mount seems designed almost as a solution to the problem of lens mounts, providing sufficient size and solidity to reasonably support almost any combination of camera and lens, while also allowing enough clearance that it's possible to adapt the mount to almost anything else. The FZ-mount first appeared on the widely-respected F3 camera and many are mated more or less permanently to a PL adapter. More recently, on the F5 and F55, they've been seen with Sony's chunky LA-FZB series adapters, which provide compatibility with 2/3” B4-mount lenses, and where the toughness of the mount is crucial.

There are few lenses natively designed for FZ-mount, probably because they'd be compatible with nothing other than FZ-mount cameras, although manufacturers such as Veydra offer it as an option. Conversely, an FZ camera can, with appropriate accessories, take anything other than E-mount lenses.

B4

Developer: Broadcasting Technology Association

Role: 3-chip video

Sensor size: 2/3”

Flange focus distance: 48mm (for red channel)

Diameter: FIXME

Introduced: 1994 (standardisation)

Cameras: 2/3” broadcast cameras.

Mechanism: Breech lock

video lens mount

Video lens mount

Attaching lenses to news cameras is a structural task as much as it is an optical one, given that a handheld camera relies entirely on this union for grip and support. As such it's no surprise to find a breech locking mount in use, although it's smaller in diameter than the PL, OCT-19 or Panavision mounts as befits the comparatively small sensors used. The principal technical oddity is that the specification calls for the three primary colours to focus at very slightly different distances from the mount, in order to accommodate the splitting of the image into those three colours for a three-sensor design.

This means that adapters to put common B4 zoom lenses on non-B4 cameras invariably need optical correction, though it can work without at apertures above f/4. Because of the huge performance of many B4 lenses, with enormous zoom ranges, low minimum apertures and handy ergonomics, there's a lot of interest in putting them on non-B4 cameras. Cheaper, older lenses intended for standard definition work can struggle with sharpness on modern cameras, though more modern, HD-rated glass is somewhat better and offers a combination of capability that's otherwise hard to match.



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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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