Gerry writes:

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?

The stronger the power, the closer it will have you be. If 1.5 is too
strong, try 1.25 (the test stand at Wal-Mart works just fine...).