Please note: I came home to watch the FL Supreme Court whilst typing this, so
if it comes out skewed, forgive.
Mike,
if you are not yet old enuf to have the approaching hardening of the lens,
which in essence means you can no longer focus "close up" , then count your
blessings and make your correction with an eyecup while ye may. We measure
the ground strength of the prescription as denoted by the curvature of the
lens in "diopters"...the "normal" range is 1 to 12, altho 990f the public
actually falls within a 1-6 range. . A minus sign (-) before the diopter
number designates it to be a near-sighted prescription, a plus sign (+) means
they are far-sighted.
Mike, if your prescription reads -1.50 (one and 1/2 diopters of minus ) for
the distance, then you are mildly nearsighted (just enuf to need them for
driving, seeing a movie or TV across the room, etc...far distances will be
fuzzy..you can fake it and go without to the prom, but you'll squint a lot!
Keep in mind when selecting your eyecup strength that if indeed the OM2s has
already built in 1/2 a diopter (-0.50) of minus (as it did in the OM-1 and
OM2) into the viewfinder to aide everyone in magnifying the viewfinder
slightly. Also, you must remember that the "apparent" distance of the
focusing screen is not in the distance, but at arm's length (I quote Shipman
here). This being the case, you must 'back off' your distance a bit in order
to approximate your "middle" ground..like computer glasses, or the middle
window in trifocals. In your case it's probably around -0.50 to -0.75. Add
the -0.50 already in the viewfinder, and you'll need at most a -1.25 or maybe
as little as -1.00. The pre-made corrective lenses are only available in
whole numbers, then I would try the -1.00 lens in an eyecup...it will be very
close to what your prescription demands. Should you desire a more exact lens,
have your Dr. refract your mid-field and have a small glass precisely ground
by your optician to fit an eyecup...a lot more expensive option. With the
small amount of correction you need, and the small amount of magnification
you need, I suspect you'll be more than happy with the -1.00 in your eyecup.
(Warning: subjective statement: I personally have always preferred a little
(I emphasize "little" here!) extra strength in my lenses rather than too
weak..after all, it's just magnification for us...my eyes are almost
identical to your prescription).
Now. on to your old age. :=) Once bifocals come into play, the entire
scenario changes. You and I are lucky in that being slightly nearsighted
means we may not need bifocals until we're 55.. and at that time you can just
carry some readers to see the camera controls but still have the eyecup to
help with focusing..I believe someone in the forum commented on the fact that
your nearsightedness comes down as your bifocal need rises..sorry about the
simplistic description, but it is the easiest way for a layman to
understand....(technically, adding the "plus" of the near prescription to the
"minus" of the distance subtracts form the distance prescription..i
know..clear as mud??) Anyway. once you truly need help focusing, you can
either go to Monovision in contacts (one eye near, one eye distance), or
distance contacts using reading glasses for the near, or fight a
'progressive' bifocal lens, tilting your head to try to find the right spot
on the lens to focus with (such fun!). Aging is such fun <not>. We'll cross
that bridge together, hopefully much later <g>.
I know this is confusing. Please reread a couple of times and it'll make
sense I hope. I know there are too many answers. I know we are all different
and have differing level of tolerance. You just gotta find what works for
you. I don't think it's so dire you must denounce focusing cameras and go
autofocus (spit, spit).
Susan
Susan Steele
Virginia USA
"Those who cast votes decide nothing, those who count the votes decide
everything."
(Joseph Stalin)
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