13 pages matching focal in this book
Results 1-3 of 13
What people are saying - Write a review
We haven't found any reviews in the usual places.
Other editions - View all
abrasive adjustment align angle of incidence base curve bend bevel bifocal block calipering carborundum chromatic dispersion concave convex crown glass curvature cutting cylinder diamond diopter distance between lenses distance portion drilling edge of lens endpiece eyewire face finger finger-piece finished flat focal focus frame geometrical center grinding slip guards half round plier height hole inch insert kryptok leaf shape left hand length lens blank lens measure light machine marked meridian meter method millimeters minus mounting neutralizing one-piece operation ophthalmic optical center optical cross optical density pad bridge pantoscopic parallel patient pattern pitch plane plano prescription pressure prism protractor pupillary width rays refracting power refracting surface retroscopic right angles rimless rough blank saddle bridge screw semi-finished shank angling side snipe nose plier sphere spherical Step number stone straight strap surface of lens temple thickness thumb trial lens usually vertical wave zylonite