ultra wide primes require many more elements than primes do and the results is more flare they will never match a prime because even primes need too many elements for high performance flare performance.
what is being sold doesnt prove anything other than market demand. Prime can outdo zooms especially on ultrawides. what about the 15mm DA lens?? -- J.C. O'Connell (mailto:hifis...@gate.net) Join the CD PLAYER & DISC Discussions : http://tech.groups.yahoo.com/group/cdplayers/ http://launch.groups.yahoo.com/group/cdsound/ -----Original Message----- From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf Of Adam Maas Sent: Wednesday, April 14, 2010 7:30 PM To: Pentax-Discuss Mail List Subject: Re: Ultra-wide zooms LOL, That may have been true 5 years ago, but it simply isn't now. Current state of the art in lenses wider than 21mm for SLR mounts are all zooms. There are no APS-C or 35mm format SLR primes which exceed the performance of zooms like the Nikkor 14-24/2.8, Zeiss ZA 16-35/2.8 or either of the 7-14/4'sfrom Oly/Panasonic at focal lengths wider than 21mm (And the only reason why 21mm matters is the Zeiss 21mm f2.8 Distagon. which simply dominates the UW prime world for performance). Current coating technology has greatly reduced the issue of increased element count (note the Zeiss 21 has an element count which is only slightly lower than the equivalent zooms) and the increased element count allows correction of distortion and removal of edge performance issues which plague even the best older UW primes. Most basic wide primes at best match the performance of today's high-end wide zooms, there have been very few new-design wide primes introduced in the last 20 years while zoom performance has increased massively and most zooms in this range are new designs form the last few years. The real downside for us is that none of the best zoom options are available in K mount. But a zoom like the DA 12-24/4 or the Sigma 10-20 (in either form) will match or exceed the performance of almost all the primes in the same range available in K mount (yes, even the legendary 15/3.5's) on APS-C. Once again, the Zeiss 21 being the exception (it is available in the ZK line) but on APS-C it's advantages show a lot less than on 35mm. -Adam On Mon, Apr 12, 2010 at 3:38 PM, J.C. O'Connell <hifis...@gate.net> wrote: > High performance ultra wide zooms (UW) dont really exist. Go with a > UW prime and even that wont match basic wide primes. > > -- > J.C. O'Connell (mailto:hifis...@gate.net) > Join the CD PLAYER & DISC Discussions : > http://tech.groups.yahoo.com/group/cdplayers/ > http://launch.groups.yahoo.com/group/cdsound/ > > > -----Original Message----- > From: pdml-boun...@pdml.net [mailto:pdml-boun...@pdml.net] On Behalf > Of David Parsons > Sent: Monday, April 12, 2010 3:12 PM > To: Pentax-Discuss Mail List > Subject: Re: Ultra-wide zooms > > > There are two common crops for dSLRs as compared to FF SLR, 1.5 (Nikon > and > Pentax) and 1.6 (Canon). > > Canon has a 1.3 crop on some of their pro bodies. > > P&S sensors are a whole other barrel of fish and there are many sizes, > but they don't correlate because the lenses are not interchangeable. > > On Mon, Apr 12, 2010 at 3:00 PM, Keith Whaley <keit...@dslextreme.com> > wrote: >> P N Stenquist wrote: >>> >>> On Apr 12, 2010, at 8:48 AM, Keith Whaley wrote: >>> >>>> Bong Manayon wrote: >>>>> >>>>> Thinking of ... >>>>> 1. Pentax DA 12-24 >>>>> 2. Sigma 10-20 >>>>> 3. Tamron 10-24 >>>>> Am not into fish-eyes so those options are out. Any votes for or >>>>> against any of those listed above? Thanks! Bong >> >>>> I don't think those focal lengths are 35mm-equivalent numbers. I >>>> suspect they're double ~ such as the Pentax DA 12-24 is really like >>>> a 35mm lens of 24-48mm focal length. Nice wide angle-to-normal >>>> lens, but hardly a fish-eye... >> >>> First, the conversion factor for angle of view is 1.5. >> >> Was Bong talking about a specific camera? I know we were talking >> digitals, but, I thought each camera had it's own conversion camera. >> In my limited experience, which does NOT include DSLRs, most cameras >> differ a little as to what their 35mm equivalent is. I avoid the >> uncertainty by referring to the owner's manual for each camera. They >> always mention it... >> >>> So the 12-24 has the same _angle of view_ on an APS-C DSLR as an >>> 18-36 would have on a conventional 35 mm frame. >> >> Cropping factor, or what I call the telephoto effect, brought on by >> the size of the sensor. In other words, the ratio derives from how >> much smaller the DSLR's sensor is compared to 35mm film size. >> See: >> >> http://www.minasi.com/photos/dslrmag/ >> >>> However, the focal length is 12-24. That doesn't change, regardless >>> of the format. Furthermore, it's not a fisheye on any format. It's a >>> rectilinear lens. In other words, the optics make the verticals as >>> true as possible given the size of the elements and the constraints >>> of physical science. Paul >> >> Quite so. Thanks Paul. >> >> keith whaley >> >> >> -- >> 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. >> > > > > -- > Aloha Photographer Photoblog > http://alohaphotog.blogspot.com/ > > -- > 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. > -- M. Adam Maas http://www.mawz.ca Explorations of the City Around Us. -- 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.
