I wear reading glasses (prescription but also +1.50 cheap ones from a
pharmacy are ok) for "reading" (books) but don't wear them to view a 19"
monitor....I don't seem to have a problem with camera focus....is this
because the apparent distance of the OM screen is beyond "reading" distance
and into mid-range?
Bruce Kolber
St. Petersburg, FL 33715
USA
----- Original Message -----
From: <DaEyeGuy@xxxxxxx>
To: <olympus@xxxxxxxxxxxxxxx>
Sent: Monday, May 21, 2001 6:29 PM
Subject: [OM] Optics 102: Aging, Apparent Focusing Distance reference, et.
al.
> In a message dated 5/21/01 11:54:04 AM Eastern Daylight Time,
> watershed@xxxxxxxxxxxxxxx writes:
>
> > Now I'm thinking that maybe the
> > distance to the focusing screen is more critical. Should I remove my
> > glasses to focus? And similarly, should one focus using the bifocal or
> > the long vision part of the lens?
>
> Again, this depends on your particular set of peepers. As we age, the
> interocular lens hardens and loses elasticity, which is why we lose the
> ability to "accomodate" (focus) and need bifocals. (In order to focus, we
> "squeeze" the flexible lens and therefore focus on whatever we look upon.
> When this hardens, no amount of squinting will flex that lens anymore!)
For
> most, this lack of 'accomodation' is mainly in the near, or reading zone,
but
> for around 20%, they also need magnification in the mid-zones as well
(hence,
> trifocals...a near, mid-range, and distance.) Progressive bifocals are
> perfect for this as they give you ALL focal lengths, an you merely move
your
> head up or down to find YOUR zone.
>
> Carl Shipman stated in his 'How to Select and Use Olympus SLR Cameras",
Rev.
> ed., 1989, p.66.:
> "The focusing screen in SLR cameras appears to be at about arm's
> length.Therefore, the diopter number you need is the one that corrects
your
> vision for objects at arm's length".
>
> Arm's length is NOT your bifocal strength (average 16" from your nose) but
> rather, your mid-range....so your abillity to focus on the focusing screen
> will depend greatly on your particular eye's aging process, and how
quickly
> your lens will harden as you age. This is the same for those that need
> computer glasses...the mid-zone is difficult for them to focus on, as
their
> hardening is much further along.
>
> If you cannot focus well with your current plano (distance) lenses, nor
with
> your readers, then go get glasses made for your mid-zone, specifying to
your
> optician the approximate distance you need. You wil also be able to use
them
> for gardening, playing the piano, and typing letters to your OM buddies.
> Later, when you get the eventual progressives, you can tilt your head up
> until you find the mid-zone for focusing.
> Susan Steele
> Virginia USA
>
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