4
4.
Depth of field
The area in acceptable sharpness in front of, and behind, the subjest in focus is called tole
Depth of Field. The aperture selected and e distance of the subject, as well as, the focal
length of a lens determines such depth of field.
Because of the longer focal length of your Reflex lens the depth of field is acutely narrow, for
example, with a 500mm f8.0 lens, at a distance of 6 feet, the depth of field is only 1/2 inch
wide. Therefore, it is recommended to first practice focusing with your lens before taking
any serious pictures, especially in close-up photography. lt is suggested that a focus
magnifier be used to help determine the depth of field sharpness under such extreme con-
ditions.
Lenses are provided with a depth of field scale. Depth of field is indicated for all distances
and F stop settings on the double scale of numbers engraved on both sides of the red center
reference line. In order to fully understand usage of depth of field, please refer to your
camera owner manual or any basic 35mm techniques guide.
5.
Cleaning and maintenance tips
The lens should always be capped when not in use. Like other precision optics, it should never
be simply wiped with tissue since this may abrade the surface with any dust clinging to it or on
the lens.
Any accumulated dust should occasionally be blown off with a syringe or available blower
brush designed for this purpose. To remove fingerprints or smears, shred the edge of a lens
tissue and roll it to make a swab: dampen it with a lens cleaner specially. made for
photographic optics and gently wipe the surface without exercising any pressure. Repeat the
procedure if necessary using a new swab. To clean, start at the center of the lens, using a
circular motion and working to the edge of the lens for best results.
When the lens is not in use, it should be stared in a cool dry place, however, if this is not
possible, a leather case with a silica gel packet will afford the same protection as an aluminum
case with poly foam liner.
6.
Fault finding
Phenomena
Causes
Measures
A lens can´t be
attached to the
camera
The lens ring mount and
the camera mount are
not aligned.
Align the lens ring mount and
the camera mount.
A lens can´t be
detached from the
camera
Incorrect rotation
direction for detaching.
If the user turns the lens
while holding the
camera, it may cause
damage to the lens.
Press the lens release button on
the camera, and lightly turn the
lens to the lens attaching and
detaching reference points, in
the direction as marked on the
camera and then pull the lens
forward.
Dark Image
Incorrect focusing.
Insufficient shutter
speed or camera shake
Turn the focus ring while
checking the indication or
checking an object visually, set
