The DA lens may not have the same image circle due to different baffling in the barrel design. Same optics but possibly different image circle. Its better to be smaller if your using a smaller sensor. See my last post as to why.
JC O'Connell (mailto:[email protected]) "Honesty is the first chapter in the book of wisdom" - Thomas Jefferson -----Original Message----- From: [email protected] [mailto:[email protected]] On Behalf Of Luiz Felipe Sent: Wednesday, April 29, 2009 6:25 PM To: Pentax-Discuss Mail List Subject: Re: image circle of DA lenses: how much smaller than FF? According to Boz, the DA* 200mm 2.8 and the FA* 200mm 2.8 have the same filter size, dimensions, number of elements and groups, and minimum focusing distance. Well, that's one possible case of one still available DA* lens capable of printing the entire 35mm frame, even if only marginally. Or a Full 35mm Frame lens ready as soon as they discover the need - wich they won't, as long as we understand Corporate Pentax's ideas for the future. Still looking for hands on results. :-) LF Luiz Felipe escreveu: > As long as I agree there is little sense in working an APS-C lens with > 35mm image coverage if you don't want your lens to be used on 35mm, I > don't believe they would take pains to restrict the image circle if the > lens design came from a 35mm version. Flare control baffles could > possibly be enhanced and the reduction on the original image area > accepted. But other than that the lens could be still be able to print > 35mm. Not a proper design from the ground, but some revision of an > existing and proved successful one. Possible case of the DA* 200mm 2.8?? > I'll be doing some spec reading at Boz' pages tonight. > > Anyway my question did assume greater lens availability from Pentax. > Since the only DA* lenses available with long reach into the 135~200mm > and 2.8 aperture are the 50~135 and the 200mm, I really should ask if > any 35mm film users ever tried those lenses on anything but APS-C > Pentaxes, and what results they got. It's all about getting more uses > for Pentax lenses, after all. > > LF > > JC OConnell escreveu: >> The other thing to note is well designed lenses for a specific format >> (like APS format and DA lenses)many times could optically work but >> because they are designed for smaller formats may have good baffling >> and front rings that will vignette if used on a larger format like >> FF. >> >> JC O'Connell (mailto:[email protected]) >> "Honesty is the first chapter in the book of wisdom" - Thomas >> Jefferson >> >> >> -----Original Message----- >> From: [email protected] [mailto:[email protected]] On Behalf >> Of John Francis >> Sent: Wednesday, April 29, 2009 1:09 PM >> To: Pentax-Discuss Mail List >> Subject: Re: image circle of DA lenses: how much smaller than FF? >> >> >> On Wed, Apr 29, 2009 at 01:35:09PM -0300, Luiz Felipe wrote: >>> I was looking for data on the available 180~200mm 2.8 lenses for K >>> and EF mounts, and found some story about how the DA* 200 2.8 is >>> related >> to >>> the former 200mm full frame and so it possibly would cover said full >>> frame. >>> >>> That got me wondering if one of the tech-oriented actually knows the >>> image circle dimensions for the DA lenses, and how much is missing. >>> I >> >>> know the difference should be proportional to the difference from >> APS-C >>> to 24x36mm, but would like ko know the size and borderline falloff >>> evolution on the DA lenses. >>> >>> Just wondering, TIA. :-) >>> >>> LF >> >> Above some focal length (well below 200mm) it's likely that just >> about any lens will have an image circle easily large enough to cover >> 36x24mm. But, as Ned Bunnell point out in his blog entry on the >> forthcoming camera, there's a difference between covering an image >> circle and covering it well. The DA lenses are not designed for >> sensors of that size, so things such as corner resolution, >> distortion, etc. may not be sufficiently high. (There again, as he >> also mentions, some older lenses may also fall short in that regard, >> even though they were designed for use on film cameras). >> >> >> -- >> 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. >> >> > -- Luiz Felipe luiz.felipe at techmit.com.br http://techmit.com.br/luizfelipe/ -- 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.
