Rear sight location

[MDriskill]

This one has probably been asked a hundred times before, but here goes...

Is there a rule-of-thumb for the optimum distance from the rear face of the rear sight aperture disk, to the eye in 10-meter air rifle?

Thanks in advance.

[Manuel Ferrán]

"The closer the disk is placed to the eye, the larger the hole appears to be in size. This makes it possible to be more accurate in centering the front sight inside it. The expediency of such close placement of the aperture sight to the eye is confirmed by data derived from research on this question. When the distance between the eye and the aperture is increased, visual acuity suffers. The most favorable distance between eye and sight is 2-5 cm (N.A. Kalinichenko, 1968)."

[MDriskill]

xxx