Globe sight

Diopter and globe sighting lines are commonly used in ISSF match rifle shooting events.

Tinted transparent plastic insert elements may also be used, with a hole in the middle; these work the same way as an opaque ring, but provide a less obstructed view of the target.

The use of round rear and front sighting elements for aiming at round targets, like used in ISSF match shooting, takes advantage of the natural ability of the eye and brain to easily align concentric circles (circles all having a common centre).

The non-aiming eye can be blocked from seeing distractions by mounting a semi-transparent occluder to the diopter.

The precise sizes of the employed components are quite subjective, and depend on both shooter preference and ambient lighting, which is why target rifles come with easily replaceable front sight inserts, and adjustable aperture mechanisms.