What you may want is a binocular loupe as used by neurosurgeons,
dentists etc. COmpound lenses, allow higher magnifications at
comfortable distances. Some on ebay for under 100.00. For
many times higher prices, available from medical / dental
supply firms with what might be considered to be safety glasses
designs.

Because of the high magnification, they're sensitive to the innate
magnification of each eye, and if your eyes are different, these
things will focus at different distances - not good for those
with tendencies toward seasickness etc.

Check with your dentist etc. for advice if you have a full
wallet, otherwise ebay / mark

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?