Archived posting to the Leica Users Group, 1997/10/01

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Subject: Re: Rangefinder alignment
From: Alfred Breull <>
Date: Wed, 1 Oct 1997 21:37:32 +0200

At 05:35 01.10.1997 -0600, you wrote:

>Why doesn't vertical misalignment affect
>focusing accuracy?  Is it just me, or do others find it more difficult to
>focus the Ms vertically than horizontally?  I usually find that for a
>vertical shot, I first focus horizontally, then realign the camera
>vertically for the shot.

You touch 3 different problems, first the misaligment effect, and both next
the abilities of the human eye and the brain's management of visul input.

1) The Leica's RF works horizontally. So, when you hold you camera
orizontally, you can focus / estimate the distance (almost at least)
correct, even if your RF's double picture is slightely dislocated in the
vertical axis.

2) The general advatange of horizontal vs. vertical perception in humans is
known and follows a fundamental biological program, resulting from
evolution. Enemies of humans could come from any horizontal  part/ axis with
high probability, but not or rather seldom from the vertical (e.g. from the

3) While teh sensibility in human's horizontal perception follows a
bilogical ("hardware") program, the vertical perception needs to be llearnt
or fixed within a very short period after birth (for some hours only, after
some weeks or months, I don't remember the exact time), in a so called
"sensible phase", and follows chaos theory. Any slight disturbance could
result in def=EDcits, even severe ones (remember the "butterfly effect" ?).=

There are some clinical trials in which very young children crawled on a
floor. The floor was not transparent, except for a 5 by 1 meter field of
(invisible) glass stones. Here you could see the floor of the room below, 3
meters down. The kids crawled from one side of the room to the other, even
across the glass stone area without hesitation, since they couldn't differ
vertically (were to young). They couldn't recognize the possible danger (to
fall down), since they hadn't learnt it till then, and their horizontal bio
programm didn't touch that part.