Mamiya M645 Super User manual

CdS Prism Finder
English Instructions

Special Features
1. The Mamiya CdS Prism Finder is an eye-level finder with a built-in Cadmium Sulfide exposure
meter for accurate exposure determination.
2. The finder enables complete coupling with the lens, the ASA speed and the shutter.
3. The viewfinder’s Exposure Indicator Needle displays the correct exposure when it is
between the two brackets on the right-hand side of the Focusing Screen.
Names of Parts
1 Aperture Ring Coupling Pin 2 Hot Shoe
3 Battery Chamber Cover 4 Eyecup
5 Diopter Correction Lens Retaining Ring 6 Eyepiece
7 Finder Release Button 8 Shutter Speed Dial
9 ASA Window 10 ASA Dial
11 Power Switch
Specifications
Viewfinder
Produces an unreversed, laterally correct image.
Image magnification is 0.74 x (with the 80mm
f/2.8 lens focused at infinity); built-in hot shoe;
removable eyecup.
Metering System Center weighted TTL full aperture; Zero-Metering
Method via Indicator Needle.
Meter Coupling Range
EV 2.85 to 17 (f/1.9, ½ sec.; f/11, 1/1000 sec.
(f/1.9 lens and ASA 100); EV 4 to 18 (f/2.8, ½ sec.
to f/16, 1/1000 sec. (f.2.8 lens and ASA 100).
Shutter Speed Range 1/1000 sec. to 1 sec.
ASA Range 25 – 6400
Power Source 1 1.5v silver oxide battery; Everyready S-76, or
equivalent

Installing the Battery
1. Using a coin or straight-blade screwdriver, remove the Battery Chamber Cover by rotating it
counterclockwise.
2. Wipe the battery with a soft, clean cloth to remove any contamination.
3. Insert the battery into the Battery Chamber with the +indication on the battery toward the
Battery Chamber, Fig. 1.
4. Using a coin or straight-blade screwdriver, securely tighten the Battery Chamber Cover, but do
not over-tighten.
Cleaning the Electrical Contacts
There are four electrical contacts on the upper, rear plane of the camera body, and four electrical contacts
on the underside of the finder.
Dirt or other contaminants on these contacts may result in a poor electrical connection that could affect
the operation of the finder.
Always wipe off any contaminants from the electrical contacts using a dry, soft, lint-free cloth before
installing the finder on the camera body.
Storing the Finder
If the finder will not be used for an extended period of time, remove the battery and store it in a cool, dry
place.
Attaching the Finder to the Camera Body
1. Before attaching the finder to the camera body, confirm that the White Dot on the Finder Release
Button is pointing upward. If the button is not pointing upward, press and release the button and
it will automatically point upward, Fig. 2.
When the White Dot does not point upward, the Finder Release Button cannot be pressed;
this position prevents the finder from accidentally being detached from the camera body.
2. Place the rear part of the finder on the camera body while holding the front of the finder slightly
upward, Fig. 3.

CAUTION
If you accidently press the Finder Release Button while the finder is attached to the camera
body, press down on the front of the finder to relock it into place on the camera body.
3. Gently lower the front of the finder onto the camera body until it stops, and then push downward
to lock the finder on the camera body.
4. Gently lift up on the finder to verify that it is securely latched to the camera body.
Removing the Finder from the Camera Body
1. While pushing the Finder Release Button with your thumb, lift the finder up and off the camera
body, and then release the Finder Release Button.
Using the Finder
1. Set the lens’ A-M Lever to its ‘A’ setting.
2. Turn the Aperture Ring so that the camera’s Coupling Pin (A) engages the lens’ Aperture Coupler
(B), Fig.4.
1. Pull out the finder’s ISO Dial (C), rotate it so that the film’s ASA speed is displayed in the ASA
Window, and then release the dial so that it locks into position, Fig. 5

2. Turn the finder’s ON-OFF Switch to its ON position, Fig. 5.
3. Set the camera’s Shutter Speed Dial to the desired shutter speed, and then set the finder’s
Shutter Speed Dial to the same speed, Fig. 6.
When photographing outdoors on a sunny day with ASA 100 speed film, recommended
shutter speeds are 1/250 or 1/125; when photographing outdoors on a cloudy day with ASA
100 speed film, 1/125 or 1/60; and 1/30 with ASA 100 speed film when photographing
indoors.
4. To set the correct exposure, turn the lens’ Aperture Ring until the viewfinder’s Exposure Meter
Needle is centered between the two brackets on the right-hand side of the Focusing Screen, Fig.
7.
If the Exposure Meter Needle cannot be centered by turning the lens’ Aperture Ring, a
change in the shutter speed is required.
If the Exposure Meter Needle indicates an overexposure, in the +area above the center of
the brackets, select a faster shutter speed, and then set both the camera’s and the finder’s
Shutter Speed Dials to the that speed.
If the Exposure Meter Needle indicates an underexposure, in the –area below the center of
the brackets, select a slower shutter speed, and then set camera’s and the finder’s Shutter
Speed Dials to the that speed.

Aperture Priority Method
1. Set the lens’ Aperture Ring to the desired aperture.
2. Adjust the exposure by turning the finder’s Shutter Speed Dial until the viewfinder’s Exposure
Meter Needle is centered between the brackets on the right-hand side of the Focusing Screen.
Shutter Priority Method
1. Set the desired shutter speed on the finder’s Shutter Speed Dial.
2. Turn the lens’ Aperture Ring until the viewfinder’s Exposure Meter Needle is centered between
the brackets on the right-hand side of the Focusing Screen.
Exposure Compensation
Since the finder measures light though the lens (TTL), exposure compensation when using filters,
extension rings, a bellows, etc. is unnecessary.
Exposure Compensation for Special Photographic Situations
When photographing under the following conditions, it may be necessary to adjust the indicated exposure,
as follows:
For strongly backlit subjects outdoors, adjust the indicated exposure by +1 stop.
To photograph a person indoors seated in front of a brightly lit window, adjust the indicated
exposure by +2 stops.
To compensate for bright interior lights, adjust the indicated exposure by +1 to +2 stops.
When copying white documents, adjust the indicated exposure by +2 stops.
When photographing a brightly lit subject against a dark background, adjust the indicated
exposure by -1 to -2 stops.
When photographing extremely dark subjects, adjust the indicated exposure by -1 stop.
Meter Coupling Range
The range of useable shutter speeds varies with the film’s sensitivity to light (ASA).
The shutter speeds shown in the shaded area of the table are beyond the meter’s range, consequently,
the Shutter Speed Dial is provided with a safety lock to prevent using these speeds.
For example, when using ASA 800 or faster film, the 1/8 speed is not available, so if the finder ISO is set
to ASA 800, the shutter speed cannot be set to 1/8.

Diopter Correction Lenses
The viewfinder is factory set for people with average eyesight.
If you are farsighted or nearsighted, and do not want to wear corrective lenses when photographing,
install a Diopter Correction Lens on the finder.
If you are farsighted, correction lenses are available in: +3, +1 and +1 diopters; if you are nearsighted,
correction lenses are available in: -0.5, -1, -2, -3 and -4 diopters, Fig. 8.
Installing a Diopter Corrective Lens on the Finder
1. Remove the finder’s Eyecup.
2. Unscrew the finder’s Diopter Corrective Lens Retaining Ring.
3. Insert the Corrective Lens into finder’s Eyecup Frame.
4. Reinstall the finder’s Diopter Corrective Lens Retaining Ring.
5. Reinstall the Eyecup.
Removing a Diopter Corrective Lens from the Finder
1. Remove the finder’s Eyecup.
2. Unscrew the finder’s Diopter Corrective Lens Retaining Ring.
3. Remove the Diopter Corrective Lens from the finder’s Eyecup Frame.
4. Reinstall the finder’s Diopter Corrective Lens Retaining Ring.
5. Reinstall the Eyecup.