crwdns2934241:0crwdne2934241:0 knoperj

crwdns2934249:0crwdne2934249:0:

the focus knob on binoculars is basically a nut that drives a screw, which adjusts the distance between the objective and the eyepiece.  If the knob turns, and the eyepiece does not move, there's a mechanical defect.

crwdns2915684:0crwdne2915684:0:

open