Setting The Stop; Focusing The Lens - Vivitar 500mm Preset Instruction Manual

SETTING THE STOP

Your 650-1300 lens has a changeable F-stop according to the focal length. (Non-auto-Iris lens) F-stop
according to the focal length is marked on the lens barrel. (Refer to the index for the distance and
diaphragm scale)

FOCUSING THE LENS

In order to get a sharp and clear image, look through the view nder of your camera, and then rotate the
focus ring which is marked "FAR <-> NEAR" until you can see a clear image through the view nder.
USING THE VIEWFINDER WITH THE TELEPHOTO LENSES
The e ectiveness of di erent types of focusing screens varies with the focal length and maximum aperture
of the lens. The range nder of microgrid prisms built into the ground glass do not work as well with longer
focal length lenses as they do with the normal camera lens and most wide angle lenses, and may partially or
full blackout the center focusing spot. When such a condition exists, focusing is best done on the ground
glass portion of the viewing screen. On some SLR cameras, long telephoto lenses appear to produce a cuto
image in the upper corners or along the entire upper edge of the view nder. Such viewing cuto is actually
caused by the size of the camera's mirror which is more adequate for the shorter focal length lenses only. The
exposed slide or negative will be una ected by this viewing de ciency.
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