Nikon FM2 - Manual (Page 22)

Shutter release button (D
The shutter release button also serves to activate the FM2's
bullt-ln exposure meter. When the film advance lever Is In the
flush position, the shutter release button is locked and will not
operate. To release the button from its locked position, pull out
the film advance lever to the standoff position. Slight pressure
on the shutter release button will then switch on both the ex­
posure meter and the LED exposure information display inside
the viewfinder. The meter and the display remain on for approx.
30 sec. after the finger is removed from the button, after whicti
they are automatically switched off to conserve battery power.
Pressing the shutter release button all the way down releases
the shutter. When you depress the button, touch the finger-
guard ® with the tip of your index finger and depress it lightly
with smooth, even pressure. This makes shutter release oper­
ation smooth and stable. With a shutter speed of 1/30 sec. or