[OM] Theta in Cosine^4 is the angle in image space

[Joe Gwinn]

At 3:56 PM +0000 12/31/01, olympus-digest wrote:
>Date: Mon, 31 Dec 2001 19:51:31 +1100
>From: "Wayne Harridge" <wayneharridge@xxxxxxxxxxxxxxx>
>Subject: RE: [OM] XA Praise 'vignetting'
>
> > One point that I haven't seen is that the XA's use of 'reverse
> > retro-focus' design (which I don't pretend to understand) accomplished ...
>
>So it's a telephoto design with 35mm focal length.  In this case the fall
>off makes more sense since the angle subtended by the image behind the lens
>will always be greater than the angle subtended by the real object in front
>of the lens.  I believe theta in the cos^4 refers to the angle on the image
>side.

That is correct. 


Joe Gwinn


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