Vortex Optics VIPER PST 2.5-10X44 RIFLESCOPE - Manual (Page 5)

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RIFLESCOPE
Side Focus Knob
Image Focus and Parallax Correction
Select Viper PST riflescopes feature a side focus knob which should be
used to fine-tune the image focus. When the image is sharply focused,
parallax error will also be eliminated.
Using the Side Focus
1. Be sure the reticle is correctly focused
(see Reticle Focus section on page 6 ).
2. Turn the side focus knob until the
target image is as sharp as possible. The
yardage numbers referenced on knob
should closely match the actual yardage
to the target.
3. Check for parallax error by moving your head back and forth while
looking through the scope. The focus is correct if there is no apparent
shift of the reticle on the target. If you notice any shift, adjust the focus
knob slightly until all shift is eliminated.
Parallax is a phenomenon that results when the target image does not
quite fall on the same optical plane as the reticle within the scope.
This can cause an apparent movement of the reticle in relation to the
target if the shooter’s eye is off-centered. Correctly focusing the target
image will allow it to fall on the same optical plane as the reticle
within the riflescope.
Turret Rotation
Vortex Viper PST riflescopes incorporate Vortex’s patented Radius Bar to
visually assist in keeping track
of turret rotations. The radius
bar provides a quick visual
reference that allows the shooter
to confirm:
• Knob orientation is correct
and has not shifted as a result
of accidental contact.
• Knob orientation is at the
zero point when using the
CRS feature.
• By watching the position
of the bar while making
elevation adjustments, the shooter is able to quickly track full, half and
quarter rotations.
To get these benefits from the Radius Bar, the “0” mark on the turret must
be indexed with the zero reference line on turret post (see Setting the CRS
Stop and Indexing Elevation Knob section on page 17).
Zero Reference Lines
Radius Bar
Turret Cap
Retaining
Screw