"Mickey Feldman" wrote: (clip)I've now passed that stage where I have to
hold the book further and further from my eyes to achieve focus, found that
my arms simply aren't long enough no matter how far I stretch, and that I
need reading glasses. So at the very least I think I'll get a helmet that
allows the use of a magnifying lens.
^^^^^^^^^^^^^^
I wear trifocals, but when I use the helmet, I switch to a pair of reading
glasses. I prefer them to the diopter corrections that fit the helmet,
because:

The helmet already has a protective front shield, a variable filter, and a
protective rear shield. If you add the diopter correction, that will be a
total of 8 surfaces that can collect dust. You can gradually accumulate
dust and scratches on all those surfaces without realizing how bad it is
getting. If you wear the correction on your face, at least that is one pair
of surfaces that you will keep clean.

When you get to the point that you need bifocals, or tri- like me, you will
find that getting a line of sight through the glasses and the helmet gets
more difficult.
^^^^^^^^^^^^^^^^
Variable shade control sounds awful useful too, for related reasons. This
may rule out the bargain
models, (clip)
^^^^^^^^^^^^^^^^^
My cheap HF helmet has adjustable shade control. The place it could fall
short (according to one poster) is in sensitivity to low current welding
light. I haven't had that problem, but that may be because of the limited
kinds of welding I do.