all else being equal (lens speed, (lens circle/sensor format, barrel size, cost) etc, a SOTA zooom cannot match nor equal a SOTA prime with only one fixed focal length. Its a simpler lens requirement for primes, thats one of the reasons why they still exist, like the DA15 and DA14
-- 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: Thursday, April 15, 2010 11:12 AM To: Pentax-Discuss Mail List Subject: Re: Ultra-wide zooms You're clearly not up on the latest developments in lens design. Comparing the best UW prime on the market (The Zeiss 21mm f2.8 Distagon T* in ZK, ZE or ZF mounts) and the best UW zoom on the market, the Nikkor 14-24mm f2.8 G, the zoom has less elements (14 elements in 11 groups for the Nikkor, 16 elements in 13 groups for the Zeiss), although the zoom makes heavy use of exotic glass to achieve this (2 ED elements, 3 aspherical elements, 1 nano-crystal coated element, the latter is unique to Nikon and seriously reduces flare). The Zeiss 21 actually does outperform the Nikkor at 21mm, but only by a small amount (and the zoom has superior flare performance despite its massive front element) and the Zeiss outperforms similar primes by a much larger margin than it does the zoom. Note that the Zeiss 21 is one of the very few truly modern wide prime designs (a 2009 update of a design from 1994), aside from the Pentax DA's, the only other new wide primes are the current set of 14's (Canon's 14LII, the Nikkor 14/2.8D which is the oldest at ~2001 and the brand new Samyang 14/2.8) and Sigma's massive f1.8's (which are good, fast but not exceptional). Simply put, modern molded aspherics, use of low-dispersion elements and other radical tech like Nikon's Nano-crystal coating has functionally removed the advantages of prime designs for wide-angle lenses unless you are trying to make a lens faster than f2.8. The requirements of a retrofocus design simply grow to a point where the requirements for a zoom are irrelevant to anything except size. Making a world class UW requires a very high element count, prime or zoom. Modern digital cameras are simply too demanding for edge performance, particularly high-MP FF cameras. As to the DA 15/4 Limited, it's actually slightly inferior in performance to the DA 14/2.8, and the latter is pretty much identical in performance to the 12-24/4 aside from the extra stop (and the DA 14 is the best performing 14 on APS-C). -Adam On Thu, Apr 15, 2010 at 10:43 AM, J.C. O'Connell <hifis...@gate.net> wrote: > 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. > -- 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.
