Re: The death knell for reflex mirrors has been sounded

"Mark Thomas" <markt@_don't_spam_marktphoto.com> wrote:
David J. Littleboy wrote:
Look it up: such telecentric lenses are used for industrial machine
vision and are quite interesting (Olympus probably makes such lenses).
But Olympus now uses "near-telecentric" on their web site, essentially
admitting that they were lying.

That sounds like an argument against the technically correct use of
telecentric.

Uh, it's an argument _for_ the technically correct use of the term, and
against using a perfectly good term for advertising BS.

What is the term for lenses that deliberately increased back
focus distance in order to clear a swinging mirror? (O:

Retrofocus. A term that's been in use for years.

Oh, yes. By the way, retrofocus designs are generally _worse_ than nearly
symmetric designs such as the Zeiss Biogon, the Mamiya 7 wide angle lenses,
and the Fuji GW690/GSW690 lenses.

That's why Olympus couldn't just say: we're using more radical retrofocus
designs. They'd be laughed out of the market.

I think we all have to agree that the less the back focal distance, the
greater the average angle of incidence. So if it is conceded that the
angle of incidence can be a problem for a given sensor...

But it's not, in the range under consideration. There aren't any problems
that aren't solved by some other lens of the same (retrofocus) design.
Neither the Leica/Contax wides, nor
the Nikon 14-24, have any problems whatsoever on FF. And the Canon 10-22 and
Nikon 12-24 do very nicely on APS-C. And even the much-maligned 17-40 makes
better 12x18 prints from the 5D than it ever did with 35mm film.

--
David J. Littleboy
Tokyo, Japan


.

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