Page 144 - FAT 105 4.17 MOODLE

Figure 20: Aperture sights.
same basic front post design. Pistols will
typically use the notch type, while rifles
may use either the aperture or notch and
shotguns may use aperture or post only.
Aperture sights are so named because of
the use of an aperture assembly for the
rear sight. An aperture is a small hole in
the rear sight used to view the front sight,
similar to the aperture that allows light to
enter a camera and create a picture. The
aperture itself acts as a collimator, a de-
vice that aligns light rays and provides a
sharp image. When the sights are properly
aligned, the tip of the front post must be
perfectly centered in the aperture’s win-
dow. The aperture itself may vary in size
for use at different distances or under dif-
ferent conditions. A larger aperture will
allow more light to pass through, creat-
ing a larger, brighter sight picture with a
larger field of view, but will also allow a
greater chance of misalignment because of
the larger aperture. A smaller aperture will
not allow as much light to pass through
and will not allow as large of a sight pic-
ture, but will provide a greater chance of
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accuracy and precision because the smaller
aperture does not allow for as much mis-
alignment. Large apertures are typically
used for close-to-mid range distances
and low light conditions, while smaller
apertures are typically used for precision
shooting. Aperture sights are also known
as “peep” and “ghost ring” sights.
Notch sights are so named because of the
use of a notch in the rear sight. The notch
is just a simple cutout in the rear sight,
which provides clearance to view and
align the front sight. When the sights are
properly aligned, the front post must be
centered in the notch with the tops of the
post and notch perfectly level. The notch
and post will vary in width, with a thicker
post and wide notch for quick acquisition
and a thinner post and narrower notch for
precision shooting. A larger notch will al-
low more light to pass through, creating a
larger, brighter sight picture with a larger
field of view, but will also allow a greater
chance of misalignment because of the
larger notch. A smaller notch will not al-
low as much light to pass through and will