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Re: [OM] 6x4.5 compared to 35mm?

Subject: Re: [OM] 6x4.5 compared to 35mm?
From: "John A. Lind" <jlind@xxxxxxxxxxxx>
Date: Sat, 12 Jan 2002 15:08:29 +0000
At 17:00 1/12/02, Winsor Crosby wrote:

As I remember it the Greeks and Romans had a proportion called the golden mean which they thought was most beautiful. It is very close to the proportions of a 35mm frame.
--
Winsor Crosby
Long Beach, California

Yes, the Greeks used it extensively in their architecture. The golden mean is used to create the "golden rectangle." If a square formed by the shorter side is removed, the remaining rectangle also has the aspect ratio of the "golden mean." The exact aspect ratio is an irrational number, approximately 1.618 : 1, and in a cropped 35mm frame (cropped) it would be approximately 22.25mm x 36mm. A 4x6 print would have to be roughly 4x6.5 inches, or 3.7 x 6 inches.

The equation for it:
If "x" is the short side, and "y" is the long side:
  y = [0.5 + (1.25)^0.5] * x
  x = y / [0.5 + (1.25)^0.5]

IIRC, the roots of the 8x10 are in early glass plate view cameras because it was a common window pane size. The most common source for reasonably flat glass was using window panes procured at the local "dry goods" store.

-- John


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