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Re: [OM] Do 21mm Zuiko's give you fish-eye effect?

Subject: Re: [OM] Do 21mm Zuiko's give you fish-eye effect?
From: "John A. Lind" <jlind@xxxxxxxxxxx>
Date: Sat, 20 Jan 2001 19:07:05 +0000
Caveat:  Paul's equations work for 35mm format only.

In the first equation, the 21.7mm is half the diagonal of a 35mm film frame. For other film formats, replace the "21.7mm" with half the frame diagonal for that format, in millimeters.

-- John

At 15:41 1/20/01, Paul Farrar wrote:
For a rectilinear lens, which all Zuikos except the 8mm and 16mm fisheyes
try to be, it's

AOV = 2 * arctan( 21.7mm / focal length )

You can easily see that a 21mm has approximately a 90deg AOV.

For lenses longer than 50mm, you can use the approximation

AOV = 2400 / (focal length)

The actual limiting number is 2486.6, but 2400 is close enough and easy to
use.


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