Sights with circle and dot reticle

Circle with a dot

— like a regular dot (see the relevant paragraph), this type of reticle is used as the main reticle in collimator sights, and as an addition to a crosshair or other more traditional reticle in optics and nightlights. However, the latter is rare, so let's focus on collimators. Compared to the simplest dot, the circle covers more visible space, but it is very visible and often more convenient when shooting offhand or sharply turning the weapon. In addition, both for a circle and for a point, the exact angular size is often indicated, which gives extended possibilities for using the aiming mark as the simplest goniometer (rangefinder) scale.