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Re: [OM] bad eye site and correct focus...

Subject: Re: [OM] bad eye site and correct focus...
From: "John A. Lind" <jlind@xxxxxxxxxxx>
Date: Fri, 11 May 2001 12:43:04 +0000
At 13:57 5/11/01, Arni wrote:

No, it's *apparent* distance. Your eyes are tricked into believing that they
are looking at a huge focusing screen ca. 2 meters away, I think. I could
explain it a lot better in Icelandic, but you'd probably just say "eh?". <g>

Arni

You did very well in English!

Chris,
The viewfinder optics are what make the apparent distance about 6 feet (two meters). If it were 2cm (about 3/4 inch) your eye would not be able to focus on the screen unless you were very, very myopic (e.g. "Mr. Magoo" near-sighted).

It finally dawned on my why I require the -2 and -3 dioptric correction lenses for my right and left eyes respectively (they are 1.25 diopter different) instead of a -3 and -4 correction. My reading prescription is +1 diopter for both eyes and the _apparent_ distance of the focus screen is at the far end of the distance range for which I require reading correction, not infinity correction. I believe this is why there are sometimes mixed results in people trying to correlate the markings on the Eyecup 1&2 correction lenses with their prescriptions.

What the markings actually mean can differ by manufacturer too. A -1 diopter Mamiya correction lens works perfectly for my right eye in the M645.

-- John


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