Joe Gwinn wrote:
At 12:56 PM +0000 11/7/03, olympus-digest wrote:
On Thursday, November 6, 2003, at 02:37 AM, Wayne Harridge wrote:
I thought the retrofocus was also necessary so that the light was
hitting the sensor (almost) square on. If you put the rear element too
close to the sensor the angle won't be right.
That is what Olympus said. Hmmmm. Actually Leica has said the same
thing. They said that their rangefinder lenses will not work well on an
M camera modified for a digital back. Some one told me that the
physical location of the rear lens element was unimportant because it
can be designed so that parallel rays emerge from a virtual point
farther away.
Yes, they can do that. This is just another way to describe a telecentric lens.
Logically, it would also be possible for the rear element to have a
diameter the same as the diagonal of the sensor and be right on top of
it. Not that such extremes are necessary, just pointing out a logical
problem with the formulation "If you put the rear element too close to
the sensor the angle won't be right."
Moose
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