Optical Terms - Continued
Figure 9-3. Newtons Rings
Parallax Shield. A device used to reduce parallax between the sighting instrument and the field of view.
Placed over the eyepiece end of the instrument it will restrict the movement of the viewers eye and minimize the apparent
displacement of one object with respect to another, that is, the reticle and the target. The parallax shield (fig. 9-4) can be
fabricated from cardboard, tape, or metal with approximately a1/l6 inch hole located in the center.
Figure 9-4. Parallax Shield
Change 2 9-3