I would like to add that this subject is one of the things I like about using FF zoom lenses on APS digital format. Whatever the original FF lens distortion was, its reduced by 1/3 on the APS format because you're only using the central portion of the designed FF image circle. In other words, FF zooms get better with respect to distortion when used on APS format, this is a GOOD thing especially if the original FF zoom was already good to begin with.
JC O'Connell [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Margus Männik Sent: Sunday, November 09, 2008 4:06 PM To: Pentax-Discuss Mail List Subject: Re: DA* 16-50 review at photozone Hi, I divide geometrical distortions to good and bad not by percentage, but how even it is. If the distortion is even, resulting arches can be easily transformed back to straight lines. I have analyzed several wide-angle zooms and many of 'em bend straight lines to complex curves that are nearly impossible to "straighten". Those lenses often measure quite OK (i.e. distortion result as percentage in Imatest is rather low), but there's no software that could effectively correct the image. Pentax DA* 16-50mm distorts quite "good", especially at wide end. BR, Margus JC OConnell wrote: > I would say it depends on what you mostly use it for, > The geometric distortion would be very bad/annoying for Horizons and > anything else that is supposed to Be straight, like buildings. Of > course you Could correct in a photoshop add-on for occasional > Usage like that, but if you used it all day > For linear things that's a pain in the arse > To have to do photoshop corrections... > > JC O'Connell > [EMAIL PROTECTED] > > > > -----Original Message----- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf > Of [EMAIL PROTECTED] > Sent: Sunday, November 09, 2008 2:37 PM > To: Pentax-Discuss Mail List > Subject: Re: DA* 16-50 review at photozone > > > Then you'l be missing out on a very fine lens. Certainly one of the > best zooms Pentax has ever produced. And I'd be surprised if it's not > a lot better than the 17-70. Paul > -------------- Original message ---------------------- > From: Boris Liberman <[EMAIL PROTECTED]> > >> Let's just say that either measured or shown by example, the >> distortion >> at wide end makes this lens a no-go for me. >> >> Boris >> >> Subash wrote: >> >>> http://www.photozone.de/pentax/405-pentax_1650_28 >>> >>> <quote> >>> >>> Verdict >>> >>> It is difficult to find a final verdict for the Pentax SMC DA* >>> 16-50mm f/2.8 ED [IF] SDM. On the one hand it has some obvious >>> problems like a weak border performance at max. aperture and very >>> pronounced lateral chromatic aberrations (CAs). On the other hand it >>> > > >>> is really very sharp and contrasty at medium aperture settings >>> (f/5.6-8) and many users may actually forgive the border problems at >>> > > >>> f/2.8 because you either stop down for conventional photography or >>> rely on the (very sharp) center for shallow depth-of-field >>> situations (e.g. portraits) anyway. The build quality of the lens is >>> > > >>> also a step up from the consumer grade Pentax lenses and the silent >>> (although not overly speedy) SDM is an extra bonus on top. The >>> pricing of the Pentax 16-50mm f/2.8 is fair relative to its >>> performance and build quality. >>> >>> </quote> >>> >> -- >> 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. > > > -- > 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. -- 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.
