Perspective (was Re: Has ultrawide angle become an overused cliche?)
in [Digital Cameras]
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From: Neil Harrington on 12 Aug 2010 21:44 "Paul Furman" <paul-@-edgehill.net> wrote in message news:xLydnf4ncKnVEPnRnZ2dnUVZ5rGdnZ2d(a)giganews.com... > David Ruether wrote: > >> as I have pointed out earlier, with ever narrower angles of view, ALL the >> several perspective *types* approach each other in appearance. You are >> confusing the "look" of a photograph with the definition of >> "perspective", >> and leaving out defining "angle of view". For more, see -- >> http://www.donferrario.com/ruether/lens_perspective_types.htm >> >> http://www.donferrario.com/ruether/lens-angle-of-view-and-perspective.htm >> http://www.donferrario.com/ruether/seeing_and_perspective.htm >> http://www.donferrario.com/ruether/lens_distortion_types.htm >> ... >>> This seems like mostly an argument about semantics but here's an example >>> that supports the idea of real differences in wide angle 'perspective'. >> >> Um, best to correct that to "angle of view"...;-) > > OK, "angle of view" is a better term. Semantics solved! :-) But that doesn't solve it at all, Paul. Again: if you take a very wide-angle shot of the distant horizon, with nothing else in the scene to lend perspective, then there is NO perspective no matter how wide the "angle of view" is. (Everything is at infinity for all practical purposes.) And because there is no perspective, someone looking at the photo has no clue as to whether its "angle of view" is wide, normal or narrow. Only when objects are reasonably close *and* three-dimensional do you get perspective. Your drawing of a half-sphere that you linked to is a good example of this. The half-sphere's surface at the corner of what would be a very wide-angle photo shows the apparent distortion you'd get with a very wide-angle lens. But the sections of the half-sphere, being flat, are still round because they are two-dimensional. > http://www.google.com/#hl=en&source=hp&q=site%3Adonferrario.com+angle+of+view > > >>> > Take a pic with a super-wide, then crop the*corner* of the image. >>> > Now try to reproduce that perspective with a telephoto lens. It >>> > could be accomplished with a stitched pano, if the stitching software >>> > stretches things but not without software distortion. >>> > >>> > Check the drawing on the bottom of this page, of a distorted sphere >>> > in the cropped corner of a wide angle view: >>> > >>> > http://www.donferrario.com/ruether/lens-angle-of-view-and-perspective.htm >>> > I don't think that could be reproduced with a telephoto lens. >>> > Put a striped ball on the left side of your desk and try it. >> Thanks for that drawing for my article.;-) It also clearly shows that >> within >> planes parallel with the sensor plane (with rectangular perspective) that >> there is no "distortion" no mater how wide the angle of view is. > > Well, there is distortion in the egg shaped silhouette of the sphere > because it's at the far corner of a super-wide. If you swing the same lens > around to center the sphere, it'll have a round outline again. The > topographical lines parallel to the image plane are perfect circles > though. Right. And those differences are the stuff of which perspective is made.
From: Savageduck on 12 Aug 2010 21:56 On 2010-08-12 18:22:18 -0700, "Neil Harrington" <nobody(a)homehere.net> said: > > "Peter" <peternew(a)nospamoptonline.net> wrote in message > news:4c6461cc$0$5502$8f2e0ebb(a)news.shared-secrets.com... >> "Neil Harrington" <nobody(a)homehere.net> wrote in message >> news:ZPGdneq_cadVwPnRnZ2dnUVZ_jOdnZ2d(a)giganews.com... >>> >>> "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message >>> news:2010081011344922503-savageduck1(a)REMOVESPAMmecom... >>>> On 2010-08-10 11:14:04 -0700, Shiva Das <shiv(a)nataraja.invalid> said: >>>> >>>>> In article <ArqdnYZXftq9yfzRnZ2dnUVZ_g6dnZ2d(a)giganews.com>, >>>>> "Neil Harrington" <nobody(a)homehere.net> wrote: >>>>> >>>>>> "Shiva Das" <shiv(a)nataraja.invalid> wrote in message >>>>>> news:shiv-663310.19271109082010(a)reserved-multicast-range-NOT-delegated.example >>>>>> .com... >>>>>>> In article <crednS_gOehk4P3RnZ2dnUVZ_g-dnZ2d(a)giganews.com>, >>>>>>> "Neil Harrington" <nobody(a)homehere.net> wrote: >>>>>>> >>>>>>>>> >>>>>>>>> And by perspective I mean what Albrecht Durer, Johannes Vermeer, >>>>>>>>> Leonardo da Vinci, and Michelangelo Buonarote meant by perspective: >>>>>>>>> the >>>>>>>>> geometrical reconstruction of a stationary point of view looking at >>>>>>>>> an >>>>>>>>> image projected on a stationary picture plane (in the case of Durer >>>>>>>>> a >>>>>>>>> glass plate, in the case of Vermeer a Camera Oscura). >>>>>>>> >>>>>>>> Obscura, I assume you mean. >>>>>>>> >>>>>>> >>>>>>> You may assume what you wish. I meant exactly what I said: Camera >>>>>>> Oscura. Brush up on it here -- I hope you read Latin: >>>>>>> >>>>>>> http://www.uniurb.it/Filosofia/bibliografie/Spinoza/camera.htm >>>>>> >>>>>> I don't. I also don't read Italian, which is what that text appears to >>>>>> be >>>>>> in. But in any case, the illustration in that article is of a camera >>>>>> obscura. (With a "b.") >>>>>> >>>>>>> >>>>>>> >>>>>>> And since you have amply demonstrated that you do not understand the >>>>>>> first thing about perspective, I will bow out of this waste of time >>>>>>> of a >>>>>>> discussion. >>>>>> >>>>>> You are probably wise to do so. You might want to instead spend the >>>>>> time >>>>>> brushing up on the difference between Latin and Italian. >>>>> >>>>> Now you are seeing the letter "B" where it isn't. The page has the word >>>>> "Oscura" six times and the word "Obscura" zero times. >>>>> >>>>> 'Nuff said. >>>> >>>> You are taking "oscura" from an old latin document, >>> >>> I think he's taking it from a document in Italian, not necessarily old. >>> >>>> and it may well have been the correct term when that document was >>>> drafted. However check; < http://en.wikipedia.org/wiki/Camera_obscura > >>>> and I think you will find your usage is the "obscure" and less commonly >>>> used one. >>> >>> Yes indeed, though it still may be commonly used among Italians. :-) >>> >>> >> >> So we have obscure and obsolete translations & definitions of obscura, >> rooted in Latin, Greek & Italian, depending upon your linguistic >> orientation. > > I don't know about Greek, and I don't know whether "camera oscura" is still > current in Italian. But it is still called a camera obscura today, within > the last few decades there were still several in operation and my guess is > they still are. They are fascinating devices in the modern form, and at > least one was built in a rotating tower so that it could scan a good part of > the local town That one used a reflex system which projected the image down > onto a large flat table. Well, I am not an Italian speaker, resorting to "Translator" from "Camera oscura", Italian to English I got "darkroom." < http://translate.reference.com/translate?query=camera+oscura&src=it&dst=en&v=1.0 > -- Regards, Savageduck
From: Paul Furman on 12 Aug 2010 22:43 Neil Harrington wrote: > "Paul Furman"<paul-@-edgehill.net> wrote in message > news:xLydnf4ncKnVEPnRnZ2dnUVZ5rGdnZ2d(a)giganews.com... >> David Ruether wrote: >> >>> as I have pointed out earlier, with ever narrower angles of view, ALL the >>> several perspective *types* approach each other in appearance. You are >>> confusing the "look" of a photograph with the definition of >>> "perspective", >>> and leaving out defining "angle of view". For more, see -- >>> http://www.donferrario.com/ruether/lens_perspective_types.htm >>> >>> http://www.donferrario.com/ruether/lens-angle-of-view-and-perspective.htm >>> http://www.donferrario.com/ruether/seeing_and_perspective.htm >>> http://www.donferrario.com/ruether/lens_distortion_types.htm >>> ... >>>> This seems like mostly an argument about semantics but here's an example >>>> that supports the idea of real differences in wide angle 'perspective'. >>> >>> Um, best to correct that to "angle of view"...;-) >> >> OK, "angle of view" is a better term. Semantics solved! :-) > > But that doesn't solve it at all, Paul. Again: if you take a very wide-angle > shot of the distant horizon, with nothing else in the scene to lend > perspective, then there is NO perspective no matter how wide the "angle of > view" is. (Everything is at infinity for all practical purposes.) And > because there is no perspective, someone looking at the photo has no clue as > to whether its "angle of view" is wide, normal or narrow. Yep. Near the center angle, it doesn't matter much. Using a fisheye lens, you can put a person in the middle of the frame (with a little distance) and they look perfectly normal. > Only when objects are reasonably close *and* three-dimensional do you get > perspective. Your drawing of a half-sphere that you linked to is a good > example of this. The half-sphere's surface at the corner of what would be a > very wide-angle photo shows the apparent distortion you'd get with a very > wide-angle lens. But the sections of the half-sphere, being flat, are still > round because they are two-dimensional. Right. And those same sections would appear as ovals once you turn the lens toward them because they are no longer parallel to the rectilinear projection (perpendicular to the axis of the lens). >> http://www.google.com/#hl=en&source=hp&q=site%3Adonferrario.com+angle+of+view >> >>>>> Take a pic with a super-wide, then crop the*corner* of the image. >>>>> Now try to reproduce that perspective with a telephoto lens. It >>>>> could be accomplished with a stitched pano, if the stitching software >>>>> stretches things but not without software distortion. >>>>> >>>>> Check the drawing on the bottom of this page, of a distorted sphere >>>>> in the cropped corner of a wide angle view: >>>>> >>>>> http://www.donferrario.com/ruether/lens-angle-of-view-and-perspective.htm >>>>> I don't think that could be reproduced with a telephoto lens. >>>>> Put a striped ball on the left side of your desk and try it. >>> Thanks for that drawing for my article.;-) It also clearly shows that >>> within >>> planes parallel with the sensor plane (with rectangular perspective) that >>> there is no "distortion" no mater how wide the angle of view is. >> >> Well, there is distortion in the egg shaped silhouette of the sphere >> because it's at the far corner of a super-wide. If you swing the same lens >> around to center the sphere, it'll have a round outline again. The >> topographical lines parallel to the image plane are perfect circles >> though. > > Right. And those differences are the stuff of which perspective is made. On further thought, perspective has two properties: distance and angle. The word 'viewpoint' might encompass both. I agree that changing the angle changes the perspective. I learned to draw isometric in high school drafting class then perspective in college: 1 point, 2 point and even 5 point fisheye perspective constructed on paper with a 3D grid and vanishing points. When you get into macro beyond 1:1, it's not uncommon for some lenses or lens combinations to exhibit reversed perspective where the vanishing point is behind you, or a telecentric lens where there is no vanishing point. For telecentric, you can only capture an image as wide as the front element of the lens. Long telephoto perspectives come close.
From: Neil Harrington on 12 Aug 2010 22:47 "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message news:2010081218562543658-savageduck1(a)REMOVESPAMmecom... > On 2010-08-12 18:22:18 -0700, "Neil Harrington" <nobody(a)homehere.net> > said: > >> >> "Peter" <peternew(a)nospamoptonline.net> wrote in message >> news:4c6461cc$0$5502$8f2e0ebb(a)news.shared-secrets.com... >>> "Neil Harrington" <nobody(a)homehere.net> wrote in message >>> news:ZPGdneq_cadVwPnRnZ2dnUVZ_jOdnZ2d(a)giganews.com... >>>> >>>> "Savageduck" <savageduck1@{REMOVESPAM}me.com> wrote in message >>>> news:2010081011344922503-savageduck1(a)REMOVESPAMmecom... >>>>> On 2010-08-10 11:14:04 -0700, Shiva Das <shiv(a)nataraja.invalid> said: >>>>> >>>>>> In article <ArqdnYZXftq9yfzRnZ2dnUVZ_g6dnZ2d(a)giganews.com>, >>>>>> "Neil Harrington" <nobody(a)homehere.net> wrote: >>>>>> >>>>>>> "Shiva Das" <shiv(a)nataraja.invalid> wrote in message >>>>>>> news:shiv-663310.19271109082010(a)reserved-multicast-range-NOT-delegated.example >>>>>>> .com... >>>>>>>> In article <crednS_gOehk4P3RnZ2dnUVZ_g-dnZ2d(a)giganews.com>, >>>>>>>> "Neil Harrington" <nobody(a)homehere.net> wrote: >>>>>>>> >>>>>>>>>> >>>>>>>>>> And by perspective I mean what Albrecht Durer, Johannes Vermeer, >>>>>>>>>> Leonardo da Vinci, and Michelangelo Buonarote meant by >>>>>>>>>> perspective: >>>>>>>>>> the >>>>>>>>>> geometrical reconstruction of a stationary point of view looking >>>>>>>>>> at >>>>>>>>>> an >>>>>>>>>> image projected on a stationary picture plane (in the case of >>>>>>>>>> Durer >>>>>>>>>> a >>>>>>>>>> glass plate, in the case of Vermeer a Camera Oscura). >>>>>>>>> >>>>>>>>> Obscura, I assume you mean. >>>>>>>>> >>>>>>>> >>>>>>>> You may assume what you wish. I meant exactly what I said: Camera >>>>>>>> Oscura. Brush up on it here -- I hope you read Latin: >>>>>>>> >>>>>>>> http://www.uniurb.it/Filosofia/bibliografie/Spinoza/camera.htm >>>>>>> >>>>>>> I don't. I also don't read Italian, which is what that text appears >>>>>>> to >>>>>>> be >>>>>>> in. But in any case, the illustration in that article is of a camera >>>>>>> obscura. (With a "b.") >>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> And since you have amply demonstrated that you do not understand >>>>>>>> the >>>>>>>> first thing about perspective, I will bow out of this waste of time >>>>>>>> of a >>>>>>>> discussion. >>>>>>> >>>>>>> You are probably wise to do so. You might want to instead spend the >>>>>>> time >>>>>>> brushing up on the difference between Latin and Italian. >>>>>> >>>>>> Now you are seeing the letter "B" where it isn't. The page has the >>>>>> word >>>>>> "Oscura" six times and the word "Obscura" zero times. >>>>>> >>>>>> 'Nuff said. >>>>> >>>>> You are taking "oscura" from an old latin document, >>>> >>>> I think he's taking it from a document in Italian, not necessarily old. >>>> >>>>> and it may well have been the correct term when that document was >>>>> drafted. However check; < http://en.wikipedia.org/wiki/Camera_obscura >>>>> > >>>>> and I think you will find your usage is the "obscure" and less >>>>> commonly >>>>> used one. >>>> >>>> Yes indeed, though it still may be commonly used among Italians. :-) >>>> >>>> >>> >>> So we have obscure and obsolete translations & definitions of obscura, >>> rooted in Latin, Greek & Italian, depending upon your linguistic >>> orientation. >> >> I don't know about Greek, and I don't know whether "camera oscura" is >> still >> current in Italian. But it is still called a camera obscura today, within >> the last few decades there were still several in operation and my guess >> is >> they still are. They are fascinating devices in the modern form, and at >> least one was built in a rotating tower so that it could scan a good part >> of >> the local town That one used a reflex system which projected the image >> down >> onto a large flat table. > > Well, I am not an Italian speaker, resorting to "Translator" from "Camera > oscura", Italian to English I got "darkroom." > < > http://translate.reference.com/translate?query=camera+oscura&src=it&dst=en&v=1.0 Right, and camera obscura obviously is the same thing. (Though not "darkroom" in the modern photography sense of course.) The earlier ones did not have lenses but were essentially very large pinhole cameras inside of which the artists worked, directly on the canvas. Very large paintings of cities, etc., were made in that way. I wish I could remember the name of the movie I once saw which had a more modern, overhead camera abscura -- but that was far too many years ago. It was a pretty impressive thing. Trying to find it via Google brings up a movie titled "Camera Obscura" which I never heard of before, but that's within the last decade and definitely not the movie I'm thinking of.
From: Neil Harrington on 13 Aug 2010 00:49
"Paul Furman" <paul-@-edgehill.net> wrote in message news:qYOdnQoW6_rQLPnRnZ2dnUVZ5oCdnZ2d(a)giganews.com... > Neil Harrington wrote: >> "Paul Furman"<paul-@-edgehill.net> wrote in message >> news:xLydnf4ncKnVEPnRnZ2dnUVZ5rGdnZ2d(a)giganews.com... >>> David Ruether wrote: >>> >>>> as I have pointed out earlier, with ever narrower angles of view, ALL >>>> the >>>> several perspective *types* approach each other in appearance. You are >>>> confusing the "look" of a photograph with the definition of >>>> "perspective", >>>> and leaving out defining "angle of view". For more, see -- >>>> http://www.donferrario.com/ruether/lens_perspective_types.htm >>>> >>>> http://www.donferrario.com/ruether/lens-angle-of-view-and-perspective.htm >>>> http://www.donferrario.com/ruether/seeing_and_perspective.htm >>>> http://www.donferrario.com/ruether/lens_distortion_types.htm >>>> ... >>>>> This seems like mostly an argument about semantics but here's an >>>>> example >>>>> that supports the idea of real differences in wide angle >>>>> 'perspective'. >>>> >>>> Um, best to correct that to "angle of view"...;-) >>> >>> OK, "angle of view" is a better term. Semantics solved! :-) >> >> But that doesn't solve it at all, Paul. Again: if you take a very >> wide-angle >> shot of the distant horizon, with nothing else in the scene to lend >> perspective, then there is NO perspective no matter how wide the "angle >> of >> view" is. (Everything is at infinity for all practical purposes.) And >> because there is no perspective, someone looking at the photo has no clue >> as >> to whether its "angle of view" is wide, normal or narrow. > > Yep. Near the center angle, it doesn't matter much. Using a fisheye lens, > you can put a person in the middle of the frame (with a little distance) > and they look perfectly normal. > > >> Only when objects are reasonably close *and* three-dimensional do you get >> perspective. Your drawing of a half-sphere that you linked to is a good >> example of this. The half-sphere's surface at the corner of what would be >> a >> very wide-angle photo shows the apparent distortion you'd get with a very >> wide-angle lens. But the sections of the half-sphere, being flat, are >> still >> round because they are two-dimensional. > > Right. And those same sections would appear as ovals once you turn the > lens toward them because they are no longer parallel to the rectilinear > projection (perpendicular to the axis of the lens). Just so. > > >>> http://www.google.com/#hl=en&source=hp&q=site%3Adonferrario.com+angle+of+view >>> >>>>>> Take a pic with a super-wide, then crop the*corner* of the image. >>>>>> Now try to reproduce that perspective with a telephoto lens. It >>>>>> could be accomplished with a stitched pano, if the stitching >>>>>> software >>>>>> stretches things but not without software distortion. >>>>>> >>>>>> Check the drawing on the bottom of this page, of a distorted sphere >>>>>> in the cropped corner of a wide angle view: >>>>>> >>>>>> http://www.donferrario.com/ruether/lens-angle-of-view-and-perspective.htm >>>>>> I don't think that could be reproduced with a telephoto lens. >>>>>> Put a striped ball on the left side of your desk and try it. >>>> Thanks for that drawing for my article.;-) It also clearly shows that >>>> within >>>> planes parallel with the sensor plane (with rectangular perspective) >>>> that >>>> there is no "distortion" no mater how wide the angle of view is. >>> >>> Well, there is distortion in the egg shaped silhouette of the sphere >>> because it's at the far corner of a super-wide. If you swing the same >>> lens >>> around to center the sphere, it'll have a round outline again. The >>> topographical lines parallel to the image plane are perfect circles >>> though. >> >> Right. And those differences are the stuff of which perspective is made. > > On further thought, perspective has two properties: distance and angle. Also shape and size, I would say. Just distance and angle perhaps if you're only considering the relationship of viewer to subject(s), but shape and size as well if you're considering the image itself that's shown in perspective. Again, your drawing of the half-sphere being an example of this. Or any photo of reasonably close three-dimensional objects, especially when taken with short lenses. With long lenses there is what I think it's reasonable to call a loss of perspective, as the photo approaches (though it can never reach) the character of an isometric drawing. > The word 'viewpoint' might encompass both. I agree that changing the angle > changes the perspective. I learned to draw isometric in high school > drafting class then perspective in college: 1 point, 2 point and even 5 > point fisheye perspective constructed on paper with a 3D grid and That 5 point fisheye perspective is something I'd like to see an example of. The term sort of boggles my mind. :-) > vanishing points. When you get into macro beyond 1:1, it's not uncommon > for some lenses or lens combinations to exhibit reversed perspective where > the vanishing point is behind you, or a telecentric lens where there is no > vanishing point. For telecentric, you can only capture an image as wide as > the front element of the lens. Long telephoto perspectives come close. Can you explain that a little more? Or direct me to a source? I'm having a problem grasping that "reversed perspective" and "telecentric" business. It looks very interesting but I'm really floundering here. |