User's Manual

9 8
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 elevation 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.
• By watching the position
of the bar while making
elevation adjustments, the
shooter is able to quickly
track full, half and quarter
rotations.
Zero Reference Lines
Radius Bar
Turret Cap
Retaining
Screw