Perspective (was Re: Has ultrawide angle become an overused cliche?)
in [Digital Cameras]
|
From: David J Taylor on 10 Aug 2010 11:25 "Neil Harrington" <nobody(a)homehere.net> wrote in message news:ofqdnSQr2Jla1vzRnZ2dnUVZ_hednZ2d(a)giganews.com... > > "David J Taylor" <david-taylor(a)blueyonder.co.uk.invalid> wrote in > message news:i3qoa4$7h4$1(a)news.eternal-september.org... [] >> >> http://www.satsignal.eu/Hols/2009/Antarctica/2009-01-24-1205-02-size.jpg >> >> >> http://www.satsignal.eu/Hols/2009/Antarctica/2009-02-02-2122-52-size.jpg > > Very nice. Of course the subject is not really the horizon in either > case, and both do have obvious clues as to the sort of lens used (with > respect to focal length). > > But what's wrong with "wide-angle perspective"? In the first shot it's > nothing else but the perspective that tips off that it was taken with a > wide-angle lens; and "wide-angle perspective" was freely used by folks > to describe exactly that effect before the Perspective Is Determined > Solely by Viewpoint Movement introduced that fallacy. :-) What's wrong is that it's using the term "perspective" in a way with which the majority do not agree. It may well be that English (in your part of the world) is moving that way. I will try and retain "wide-angle view" for reduced ambiguity. Cheers, David
From: David Ruether on 10 Aug 2010 11:27 "Peter" <peternew(a)nospamoptonline.net> wrote in message news:4c615c9c$0$5496$8f2e0ebb(a)news.shared-secrets.com... > "David Ruether" <d_ruether(a)thotmail.com> wrote in message news:i3ppsj$3ln$1(a)ruby.cit.cornell.edu... >> Ah, but the brain *doesn't* correct it to rectilinear perspective! >> THAT'S what's so much fun to show people (that the way they >> think they see isn't the way they really do see...;-). > IIRC There have been some experiments where people were fitted with prism glasses to make everything appear upside down. The > glasses were left on for some period of time. After a while the upside down illusion corrected itself and when the glasses were > removed, everything appeared upside down again. > I am going from memory and too lazy to find the paper. > > <good stuff snipped> <good DR stuff restored...;->: "Ah, but the brain *doesn't* correct it to rectilinear perspective! THAT'S what's so much fun to show people (that the way they think they see isn't the way they really do see...;-). There are simple exercises that permit people to attend to their off-center field of vision, and once that is accomplished, it is easy to see under some conditions of high color or tone contrast the clear curvatures of the fisheye perspective type. Also, logically there can be no 180-degree rectangular perspective image (the image plane would be infinitely large, and the "lens" FL would be zero), although we do see slightly more than 180 degrees horizontally, so there cannot be anything near a 180-degree fisheye-to-rectangular perspective conversion. For more, with an image approximation of how we do see, go here -- http://www.donferrario.com/ruether/seeing_and_perspective.htm (There are more articles on perspective, here -- http://www.donferrario.com/ruether/articles.html .)" > -- > Peter Yes - the brain can learn to apply *possible* corrections (exchanges of up and down, left and right orientations - and to synthesize missing parts in the visual field, which we all have), but not impossible things, such as converting a 180+ degree fisheye view into a 180+ degree rectangular-perspective view. Partly (maybe mostly...;-) why most people assume that they see in rectangular perspective is that most people visually "attend" to only a narrow angle of view at any one moment and "construct" their impression of visual reality from a large series of such narrow views - and within a narrow angle of view, all the several possible perspective types look nearly the same... --DR
From: bugbear on 10 Aug 2010 11:43 Neil Harrington wrote: > "bugbear" <bugbear(a)trim_papermule.co.uk_trim> wrote in message > news:1KOdnRBZo9FzlfzRnZ2dnUVZ7vU3AAAA(a)brightview.co.uk... >> Neil Harrington wrote: >>> "Shiva Das" <shiv(a)nataraja.invalid> wrote in message >>>> <http://www.flickr.com/photos/52865695(a)N03/4875633691/> >>>> >>>> All I did was crop the 11mm photo to the same field of view as the 35mm >>>> photo. There is absolutely no difference in the perspective. >>> Cropping the photo changes its perspective. >> OK. Would you please define, as clearly, carefully and explicitly >> as you can, what you mean by "perspective" > > <groan> > > If we're going to start getting into arguments about lengthy definitions of > rather ordinary terms, this will have to wait until I get back as I'm going > out of state in a little while. > > But briefly, in the sense we are using the term here, perspective is the > rendering on a two-dimensional surface of the shapes and apparent > relationship of objects (or parts of a single object) in a three-dimensional > world. Excellent. Now how in $DEITY's name would cropping alter that? BugBear
From: Savageduck on 10 Aug 2010 11:56 On 2010-08-10 08:27:54 -0700, "David Ruether" <d_ruether(a)thotmail.com> said: > > "Peter" <peternew(a)nospamoptonline.net> wrote in message > news:4c615c9c$0$5496$8f2e0ebb(a)news.shared-secrets.com... >> "David Ruether" <d_ruether(a)thotmail.com> wrote in message >> news:i3ppsj$3ln$1(a)ruby.cit.cornell.edu... > >>> Ah, but the brain *doesn't* correct it to rectilinear perspective! >>> THAT'S what's so much fun to show people (that the way they >>> think they see isn't the way they really do see...;-). > >> IIRC There have been some experiments where people were fitted with >> prism glasses to make everything appear upside down. The >> glasses were left on for some period of time. After a while the upside >> down illusion corrected itself and when the glasses were >> removed, everything appeared upside down again. >> I am going from memory and too lazy to find the paper. >> >> <good stuff snipped> > > <good DR stuff restored...;->: > > "Ah, but the brain *doesn't* correct it to rectilinear perspective! > THAT'S what's so much fun to show people (that the way they > think they see isn't the way they really do see...;-). There are > simple exercises that permit people to attend to their off-center > field of vision, and once that is accomplished, it is easy to see under > some conditions of high color or tone contrast the clear curvatures > of the fisheye perspective type. Also, logically there can be no > 180-degree rectangular perspective image (the image plane would > be infinitely large, and the "lens" FL would be zero), although we > do see slightly more than 180 degrees horizontally, so there cannot > be anything near a 180-degree fisheye-to-rectangular perspective > conversion. For more, with an image approximation of how we do > see, go here -- > http://www.donferrario.com/ruether/seeing_and_perspective.htm > (There are more articles on perspective, here -- > http://www.donferrario.com/ruether/articles.html .)" > >> -- >> Peter > > Yes - the brain can learn to apply *possible* corrections > (exchanges of up and down, left and right orientations - and > to synthesize missing parts in the visual field, which we all have), > but not impossible things, such as converting a 180+ degree > fisheye view into a 180+ degree rectangular-perspective view. > Partly (maybe mostly...;-) why most people assume that they > see in rectangular perspective is that most people visually > "attend" to only a narrow angle of view at any one moment > and "construct" their impression of visual reality from a large > series of such narrow views - and within a narrow angle of > view, all the several possible perspective types look nearly > the same... > --DR ....and then there is telephoto compression when viewpoint/camera/subject "perspective" is maintained. I think a big point of contention is understanding that a change in how an image "looks" because of a change in FL, or sensor size is not a change of "perspective." This is an error I have been guilty of. Strictly speaking perspective is related to viewpoint/camera/subject position. Where lens induced distortion, and compression, with maintained viewpoint/camera/subject position, is just that, a change to the image/scene from the same perspective. So one could say you can get several different views of a single scene from the same perspective, with lenses of different FL, or even with different cameras, provided the subject to sensor plane is maintained as a constant. -- Regards, Savageduck
From: Neil Harrington on 10 Aug 2010 12:01
"David J Taylor" <david-taylor(a)blueyonder.co.uk.invalid> wrote in message news:i3rr1h$7p2$1(a)news.eternal-september.org... > > "Neil Harrington" <nobody(a)homehere.net> wrote in message > news:ofqdnSQr2Jla1vzRnZ2dnUVZ_hednZ2d(a)giganews.com... >> >> "David J Taylor" <david-taylor(a)blueyonder.co.uk.invalid> wrote in message >> news:i3qoa4$7h4$1(a)news.eternal-september.org... > [] >>> >>> http://www.satsignal.eu/Hols/2009/Antarctica/2009-01-24-1205-02-size.jpg >>> >>> >>> http://www.satsignal.eu/Hols/2009/Antarctica/2009-02-02-2122-52-size.jpg >> >> Very nice. Of course the subject is not really the horizon in either >> case, and both do have obvious clues as to the sort of lens used (with >> respect to focal length). >> >> But what's wrong with "wide-angle perspective"? In the first shot it's >> nothing else but the perspective that tips off that it was taken with a >> wide-angle lens; and "wide-angle perspective" was freely used by folks to >> describe exactly that effect before the Perspective Is Determined Solely >> by Viewpoint Movement introduced that fallacy. :-) > > What's wrong is that it's using the term "perspective" in a way with which > the majority do not agree. Well, a majority of the few *here* who've taken part in the debate do not agree, that's true. I'll bet thousands elsewhere have used the term "wide-angle perspective" frequently, easily and in perfect comfort. In fact where I first saw the argument used against it, I think in Pop Photo perhaps 20 years ago, it was precisely that common use of "wide-angle perspective" that the author was arguing against -- using the same "proofs" (or similar) that have been dutifully repeated here. Again, all such "proofs" depend in one way or another on resizing the center ONLY of a photo, which obviously cannot change its perspective -- they do not and cannot be successfully applied to the edges and/or corners, though ALL parts of a picture contribute to its perspective. > It may well be that English (in your part of the world) is moving that > way. I will try and retain "wide-angle view" for reduced ambiguity. As you like, David. But where apparent it's still perspective that conveys the, uh, wide-angleness. :-) |