HI, I was reffering to FF zoom lenses which never venture that short into 15mm land AFAIK. FF 15mm lenses are the 10mm of APS in terms of design parameters So I wouldnt expect one to perform as well as a 16mm aps lens even with the FF cropping on aps.
When it comes to distortion, I dont care about numbers or percentages, etc. If I can EVER notice it in a real photo, any real photo, not a test pattern, it really nags me. Now if you are talking a 15mm FF or a 10mm aps lens, some visible distortion is probably just a fact of life for any lens made for 35mm old school (long registration) SLRs because of the extreme retrofocus design. On large format, without any retrofocus, it might be possible to completely eliminate all visisble distortion that wide, but on a DSLR, Im not going to beleive it until I see it at 10mm APS / 15mm FF. JC O'Connell [EMAIL PROTECTED] -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of PN Stenquist Sent: Sunday, November 09, 2008 8:48 PM To: Pentax-Discuss Mail List Subject: Re: DA* 16-50 review at photozone But none of them are wide enough to replace even this zoom, let alone the 12-24. For those of us who must shoot wide, there are few options. (BTW, the A 15 distorts a lot more than the DA* 16-50 at 16mm or the DA12-24 @ 12 mm. Paul On Nov 9, 2008, at 4:12 PM, JC OConnell wrote: > 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. -- 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.
