I dont think so, if the film was so insensitive to light angle hitting it and digital is very sensitive to it, its possible even a central portion of a FF lens has too much angle for APS digital usage.
JC O'Connell (mailto:[email protected]) "Honesty is the first chapter in the book of wisdom" - Thomas Jefferson -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Joseph McAllister Sent: Monday, May 11, 2009 5:07 PM To: Pentax-Discuss Mail List Subject: Re: DA* 60-250 at B&H 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. If that was the case, would not the center portion of a lens designed to cover full frame or larger have these properties? I'm not an optical engineer, and it's hard for me to wrap my brain around the visual of more than one point of light passing through an optical assembly at a time. This concept may have been BS propagated by the industry to get us to buy the newer, lighter, more plastic offerings they have come out with. Comments? Joe On May 11, 2009, at 06:54 , Paul Stenquist wrote: > True enough. I haven't tried my DA* 50-135 on full frame, but I > expect the results would be similar. I know the DA 50-200 covers > full frame. But if you believe Ned and the Pentax website, none of > these lenses were designed for full-frame use. As you point out, the > 60-250 may be different in that regard. Or not. Some of those early > roadmaps were full of confusing nomenclature. > Paul > On May 11, 2009, at 9:45 AM, Mark Roberts wrote: > >> Paul Stenquist wrote: >> >>> Well, there you have it. Only minor vignetting. Would that >>> increase or >>> decrease at a smaller aperture? >> >> It's probably falloff, rather than vignetting, and it would improve >> at >> smaller apertures. >> >>> In any case, it's probably useable on full frame, although I would >>> think it's optimized for APS-C. >> >> Since it was originally designated the "D-FA 60-250" I expect it was >> designed for full-frame (they probably changed the designation to DA >> when they decided to eliminate the aperture ring), but since >> virtually >> all lenses show some light falloff at wide apertures and are sharper >> in the center than the corners, any lens could be considered >> "optimized for APS-C" :) Joseph McAllister [email protected] http://gallery.me.com/jomac http://web.me.com/jomac/show.me/Blog/Blog.html -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions. -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
