Let's Photograph Comet 46P Wirtanen

Paul Schlyter:
If the numerator is always 20, what does this 20 mean? Is 20/20 in
some way different from, say, 25/25 or.30/30?

20/20, or metric 6/6 = 1. It's explained at
https://en.wikipedia.org/wiki/Visual_acuity#Measurement. 20/25 for a
person like me with macular degeneration is considered to be very good.
Again, that's my left eye. I don't have a number for my right eye, but
subjectively, it is not very useful at the moment. We'll "see" what the
new eyeglasses bring in a couple of weeks.

--
I agree with almost everything that you have said and almost everything that
you will say in your entire life.

usenet *at* davidillig dawt cawm