Mamiya 7 II - Manual (Page 15)

Mounting/Removing Lenses
Precaution for mounting/removing lenses
1) As the rangefinder coupling roller is precisely
adjusted, be sure not to touch with your hand or
move it with finger.
2) Gold plated electronic contacts are located inside
the bayonet mount and at the rear of each lens. If
oil, dirt, or other foreign matter collects on the
contacts, poor electronic information transfer
may result. When soiled, use a clean cloth to
wipe them.
3) Be careful not to damage the rangefinder
coupling lever and the shutter cocking lever at
the rear of each lens.
4) When mounting the 43mm, 50mm and 65mm wide
angle lenses make sure that the rear lens rims do
not touch the rangefinder coupling roller.
Position the front face of the lens which has been
removed as shown in the left illustration.
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