The focus is not working

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.

I have binoculars, got from my father, I would like to make him too

We were told at the institute to practice the presence of binoculars, in our profession without it anywhere. Since I never held it in my hands, I immediately rushed to search the Internet. I found this site with a detailed description of https://opticzoo.com/best-hunting-binocu... there are suitable characteristics for the necessary conditions. But I wonder how they will be in practice? Can someone tell me which is more practical?