Are you trying to imply that Pentax and other major brand multicoated lenses have not been "wideband" color neutral across the entire VISIBLE spectrum until these DA coatings came along? That seems unlikely to me.
JC O'Connell hifis...@gate.net -----Original Message----- From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf Of Graydon Sent: Thursday, April 16, 2009 10:46 AM To: Pentax-Discuss Mail List Subject: Re: DA55* 55/1.4 follow-up On Thu, Apr 16, 2009 at 03:38:13PM +0100, mike wilson scripsit: > ---- Graydon <o...@uniserve.com> wrote: > > On Thu, Apr 16, 2009 at 09:24:54AM +0100, mike wilson scripsit: > > > Hmmmm. High build quality verus computerated optical design. Old > > > but high QC versus new and unknown. Really hard to call on that > > > one, even before we start wittering about stuff like bokeh. Think > > > I'll go buy a lottery ticket. > > > > The DA coatings are better than the FA coatings; I'd be more than a > > little surprised if the FA coatings weren't better than the M > > coatings. > > > > Can't leave that out. > > IIRC, K and M coatings increase transmission from 96% to 99.8% per > interface, or something in that order. Not much space there for > improvement, although there may be a bit of wriggle room on colour > rendition. Shape of the colour transmission curve, too; most coatings do a better job with the red end than the blue end of visible light, and no one's managed an actually flat colour transmission profile yet, equally good (or bad) all the way across visible light. Taking pictures of purple or dark blue flowers with the DA 55-300 vs the FA 100 macro, or the DA 35 Ltd vs the FA 31 Ltd makes it really really obvious (at least to me) that the DA coatings have a different colour curve, one that's missing a dip or a squiggle at the high blue end, compared to the FA coatings. -- Graydon -- 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. -- 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.
