Nikon F3 - Manual (Page 63)

L Keep the lens clean.
Keep the lens surfaces free of fingerprints and dust as much as
possible. Remove dust with a blower brush or lens tissue. Never use
cloth or ordinary tissue. If smudges or fingerprints persist, use lens
tissue moistened sparingly with alcohol or lens cleaner.
4. Do not expose the camera to high temperatures.
Keep the camera away from places where the temperature is apt
to be high, such as on the beach under direct sunlight or in the trunk
of a car.