Mamiya 645 AF and 645 AFD series

From Camera-wiki.org
Revision as of 12:25, 16 July 2011 by Dustin McAmera (talk | contribs) (Divided into sections with titles)
Jump to: navigation, search

The 645 AF is a medium-format SLR camera made in Japan by Mamiya, the company's first autofocus camera. It was released in Japan in September 1999.[1] It was followed in December 2001 by the 645 AFD, a version of the same camera made compatible with some digital backs (not produced by Mamiya at the time), and Mamiya produced improved models, the 645 AFDII and 645 AFDIII later. These retain the ability to use either film or a digital back, switching from one to the other quickly, mid-roll if desired.

The cameras have a new bayonet lens mount incorporating several electrical contacts, to support the use of AF lenses. The lenses attach in the same way as with the previous mount, by aligning the lens with the red spot on the body and twisting to fasten the bayonet. The release is also unchanged; a sliding button on the left side of the camera body. The new mount is compatible, in a limited way, with the lenses for the preceding models (the Mamiya M645 and M645 Super/Pro series cameras). The manual-focus lenses can be fitted to the new mount, but the cameras do not have the pin to mate with the aperture yoke on these lenses, so stopped-down metering must be used. There is also a special focusing screen, with a manual-focusing aid (a microprism/rangefinder spot) for use with manual lenses.

Whereas the M645 Super/Pro series cameras had polycarbonate bodies, the 645 AF series have aluminium bodies. Perhaps Mamiya was sensitive to criticism of the previous, plastic body; the introduction of the manual for the AF uses the phrase 'heavy professional use' a number of times.


645 AF

Many of the features of the 645 AF are retained from Mamiya's previous series of 4.5x6cm SLR cameras (the M645 Super and related models). However, the camera is not built in the modular way that those cameras were; the power film winder is built-in, as is the AE prism viewfinder; a waist-level finder cannot be used (although there is a right-angle eyepiece attachment).

Exposure settings

Exposure settings are controlled via menu options displayed in an LCD on top of the winder grip, and selected with wheel controls (one by the shutter release button, and another at the back of the grip, by the user's thumb) in combination with a main mode dial. The exposure settings in use are also displayed at the bottom of the viewfinder. The mode dial has settings for metered manual exposure control (M), shutter-speed priority AE (Tv), aperture-priority AE (Av), programmed AE (P), auto flash (X) and a setting for long exposures (T). The shutter release button has settings for single or continuous exposures, and a locked position. It is threaded for a standard cable release. There is also a socket on the left side of the body for electronic releases.

Shutter

The camera has a focal-plane shutter with aluminium blinds. This gives speeds from 30 seconds to 1/4000 second, in steps of 1/8 stop when in AE, or 1/2 stop when manually set. 'B' is available as a setting in the 'M' mode, and there is 'T' mode for very long exposures, as noted above. The shutter synchronises for flash at 1/125 second. Both shutter blinds are automatically retracted (i.e. the shutter opens) when the film back is removed (to avoid damage to them) or when there are no batteries in the camera.

Metering

As in previous camera series, the prism finder has settings for spot (S) or centre-weighted average (A) metering, and a setting (A-S) in which the camera automatically selects one or other of these, based on the variation in brightness in the scene. The meter measures between EV 2 (1 second at f/2) and EV 19 (1/2000 second at f/16) at ISO 100, and allows exposure compensation by up to three stops in either direction; any selected compensation is shown in the VF display. The viewfinder eyepiece has a shutter to keep out light when the camera is used away from the eye, and built-in diotric adjustment.

Focusing

On the bottom left (i.e. the user's left when behind the camera; the side opposite the grip) of the front of the body is the focus mode switch, which sets the behaviour of the auto-focus function. There are three settings:

  • Single-focus ('S'). In this mode, when the shutter release is half-pressed, the camera focuses, using the area in the small rectangle marked across the centre of the VF. When satisfactory focus is achieved, the focus is fixed (i.e. the camera stops adjusting it), and the focus marker in the VF display lights. The shutter will not release until the marker has lit. Mamiya also describe this mode as focus priority', and suitable for still subjects. The fixed focus is cancelled if pressure is removed from the release button. This mode allows the familiar method in which the scane may be reframed after focusing, while holding the shutter release button down, to place the focused subject off-centre in the frame.
  • Continuous focus ('C'). In this mode, when the release button is half-pressed, the camera continuously adjusts the focus as the scene is reframed by the user. The focus mark lights when the current scene has been focused, but the shutter may be released at any time. Mamiya describe this mode as 'release priority', and suitable for moving subjects.
  • Manual focus ('M'). In this mode, focusing is done by the user with the lens' focus ring. The VF shows focus guidance arrows in addition to the focus marker (these only work with lenses of f/5.6 or wider).

The camera has an infra-red lamp on the front of the body, next to the shutter release. This lights in the Single focus mode, to assist the auto-focus function in conditions of dim light or low subject contrast.

Film holders

The 120 film back for the 645 AF is superficially similar to that for the earlier M645 Super; it is a detachable chamber, with a metal dark slide, into which a film insert (comprising a pair of spool-holders with a pressure plate and rollers) can be fitted. However, the back for the 645 AF has an LCD and 'up' and 'down' buttons to set and display the film type and speed (between ISO 25 and 6400), and requires its own battery (CR2032) to support this. It also has more electrical contacts than the earlier film back, and the two are not interchangeable. The same film insert accepts both 120 and 220 roll film; the pressure plate may be rotated, to adjust it for the different thickness of 120 and 220 film. The back automatically advances the film to frame 1 provided the paper leader is attached to the take-up spool. A Polaroid back also exists.

In addition to the automatic retraction of the shutter blinds, the camera has the same common-sense interlocks as the Super to prevent accidental exposure of film:

  • The dark slide cannot be opened when the back is off the camera.
  • The back cannot be detached when the dark slide is out.
  • The shutter cannot be released when the dark slide is in.

Other features

As with earlier models, the camera has a tripod socket which can be adjusted to ⅜ or ¼-inch size. There is a mirror-up lever on the left-hand side of the body.

There is a hot shoe on top of the prism, as well as a PC socket on the left side. The camera is compatible with some Metz flashes for through-the-lens flash metering, with an adapter.

The camera requires six AA batteries, which are loaded in a removable holder that fits into the grip. The LCD display shows the battery condition continuously when the camera is switched on (i.e. when the shutter release is not in the locked position). An external battery holder exists (to be kept in a pocket, for cold-weather use); this connects to a socket in the base of the camera.


645 AFD



Notes

Links

User's manuals (pdf) at Mamiya USA: