On Sep 18, 9:43 pm, Gerry wrote:
Trying to figure out the link between magnification and focal length.
I need glasses to be able to read and see what I''m doing clearly on
my lathe but the 1.50 safety glasses I have force me to get too close
to my work. Looking for something with a focal length of maybe 22" so
I can stand at a comfortable position. Does that mean a stronger lense?

http://www.doneganoptical.com/optivisor.php

I like the 3 at 14" for bench and lathe work but the 2 fits your
request better.

jw