It is my understanding the diopter correction used should be from the
"distance" prescription, not the one for "reading" (close focus) lenses.
This would be in line with dioptric correction for other makes of cameras.
The appparent distance of the focus screen and display in the viewfinder is
on the order of at least several feet (4-6 feet; 1-2 meters). I think it
would be rare that someone would need "reading" or close focus correction
at that distance. This would make sense in design to keep the apparent
distance beyond the range of close focus issues for those (like me) who
have to use reading lenses. I also wear distance glasses and with the
OM-1n there is no problem viewing the focus screen as long as I am wearing
them.
Question for the individual who asked about the table: does he (she) wear
corrective lenses for "distance" or only for reading? What is _that_
prescription? I suggest trying the closest dioptric correction lens from
the table for that prescription (prescription-2 diopters as the table states).
BTW, the other way to get dioptric correction is to take a lens from a pair
of old glasses having the same _distance_ (not reading) correction as the
current prescription and have a dioptric correction lens cut from the
middle of it. This requires that the eyecup allows replacing the lens in
it. Most prescriptions are given in increments of 1/4 diopters. Also, if
you do that, make certain the lens used is for the eye you normally use to
look through the viewfinder. Many people with corrective lenses for
distant vision have a different prescription for the left and right eyes.
-- John
P.S. The B&H area for the Oly eyecup 2's with diopters agrees with Hans'
eSIF and your FAQ; of course they could have pulled their info from Oly's SIF!
At 16:23 6/27/00 , Lee Hawkins asked:
>
>Hi all:
>Several years ago, someone sent me a copy of the chart of powers of
>dioptric correction lenses that is found in the Olympus Sales Info File.
>Hans has since put this chart up on his website, and it matches the
>version I have in the FAQ. Recently, however, someone else has pointed
>out that, using their +1 diopter reading glasses, they can focus on the
>viewfinder in their OM-2N. They then looked up +1 diopter in the table
>below, and ordered a -1 diopter marked lens, assuming that this would
>give the same combination as their reading glasses. It didn't. Could
>this table from Olympus be incorrect? Or am I misinterpreting it?
>Given that Shipman claims the viewfinder itself has a power of -0.5
>diopters, I can't seem to reproduce the values in the table. Seems to
>me all the values on the right should should be X.5 instead of X.0
>diopters. What am I missing?
>
>>From the FAQ:
>
> The number engraved on the lens is the final diopter in conjunction
> with OM body and is listed on the left. The initial (actual)
> diopter of each Dioptric Correction Lens is listed on the right.
>
> That is also the value of corrective glasses to which it corresponds.
> +2 +4
> +1 +3
> 0 +2
> -1 +1
> -2 0
> -3 -1
> -4 -2
> -5 -3
>
>Cheers,
>--Lee
>________________________________________________________________________
>R. Lee Hawkins lhawkins@xxxxxxxxxxxxxxxxxxxxxxxxxx
>Observatory Assistant/Engineer hawkinsrl@xxxxxxxxxxxx
>Dept. of Physics & Astronomy http://brashear.phys.appstate.edu/lhawkins
>Appalachian State University Ph. 828-262-7331
>Boone, North Carolina 28608 FAX: 828-262-2049
>________________________________________________________________________
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