On May 19, 11:05*am, (Steve Willner) wrote:
In article ,

*Ian writes:
I am currently using 1.75, but I will have to toy with other strengths
and use two separate pairs.

It may help you to know that "diopters" are the reciprocal of focal
length in meters. *If your eyes are corrected for distant vision, the
computer screen at 1 meter distance needs about 1 diopter of
correction, and printed material at half a meter needs about 2
diopters. *(Feel free to put in your own preferred distances and do
the arithmetic.) *Bifocals work well for me.

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner * * * * * *Phone 617-495-7123 * *
Cambridge, MA 02138 USA * * * * * * * *

I see, so that number written on drugstore glasses, are diopters not
multiples of magnification. That does help. Thanks.