On Mon, May 11, 2009 at 02:07:07PM -0700, Joseph McAllister scripsit: > From information absorbed by my little noggin way back when, I am now > under the impression that "optimized for aps-c" meant, among other > things, that it was an effort to make the light rays more parallel as > they struck the sensor to prevent the color fringing we see in our > digital images. Supposedly caused by the angle of incidence of light > rays to the sensor pixels in the corners and periphery of said sensor, > which allowed the light ray to strike more than one pixel under such > circumstances.
Remember that the sensor isn't sitting out there in the air; it's got a cover, the cover has thickness, and reflects and refracts. The rear lens element reflects, too. Film is an absorptive medium -- the photon hits and sticks -- so the optical behaviour of the digital sensor stack is considerably different. "more vertical" incident light may help with getting consistent behaviour from the sensor stack; there's certainly no obvious reason that you couldn't design a full frame lens that way. It'd have to be the whole lens, though. This may be part of Pentax's decision not to go with full-frame digital; they'd have to redo the whole lens lineup to get performance they considered acceptable. -- Graydon, who really does think it's going to be APS-C, MF, and nought else from Pentax -- PDML Pentax-Discuss Mail List PDML@pdml.net http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
