At 10:17 PM +0000 10/12/03, olympus-digest wrote:
>Date: Sun, 12 Oct 2003 15:15:16 -0700
>From: Moose <olymoose@xxxxxxxxxxxxx>
>Subject: Re: [OM] E-1 lenses resolution vs. conventional lenses - fact or hype?
>
>Joe Gwinn wrote:
>
> >.........
> >The bounding case is to draw a cross-section of the lens and imager, with
> >the cross-section cut on a diagonal of the sensitive surface (image frame),
> >so we can see right out to the corners of the frame. The cross-section
> >plane must include the optical axis of the lens. Draw two lines, from the
> >extremes of the back lens to one of the frame corners.
> >
>This doesn't work with retrofocus wide angle designs, which are the
>majority of the problem. With the back focal node behind the back
>element, this method will understate the angle of incidence problem.
Even though it is true that the node may be in the image space between back
lens and imaging surface, I don't see how this can matter. Light travels in
straight lines, so the angle of arrival cannot be sharper than the construction
given above, or the light would have to emerge from some non-transparent part
of the lens.
Joe Gwinn
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