From: David Ruether on

"Paul Furman" <paul-@-edgehill.net> wrote in message
news:AKCdnTDHmc6opfnRnZ2dnUVZ5oOdnZ2d(a)giganews.com...
> Neil Harrington wrote:
[Exercising NH's repeat stubborn inability to "learn" in this and other threads...]

>> I have already answered this in more than one previous post. I wish you
>> would read all the posts so I don't have to repeat the same thing over and
>> over. But I will again, this one time. (If the same question keeps coming up
>> I may make a boilerplate for it.)
>>
>> Perspective is a quality of the ENTIRE PICTURE, not one small part. All
>> "proofs" that perspective is solely a function of viewpoint (and that focal
>> length has nothing to do with it) are based in one way or another on
>> resizing the central portion of the picture only, as if the center and only
>> the center established perspective for the whole. Obviously, magnifying or
>> reducing one part of the picture does not (and cannot possibly) change the
>> perspective.
>>
>> Here's a reductio ad absurdum question for you. If only a small part of the
>> center were important to perspective, why not make that part smaller still?
>> Why not just keep shrinking it? Suppose at the very center of the picture
>> there is a pea -- if we should go so far as to crop away everything except
>> that one little pea, would that picture of the pea still convey the full
>> perspective of the original picture?

Yes, if there is still enough information to indicate the *perspective type*
used in taking the original WA photo from which the crop was made - but,
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
I know it is useless pointing these out since you refuse to consider anything
but what you already "know", but others might care to learn something...;-)

>> Wide-angle pictures often contain important elements of perspective that
>> simply are not there in long-lens pictures of the same subject taken from
>> the same viewpoint. And those elements of perspective near the edges of the
>> wide-angle picture CANNOT BE DUPLICATED with a long lens. This is of course
>> assuming there are three-dimensional objects there that can contribute to
>> perspective. (A wide-angle picture of blank sky would contain no perspective
>> at all.)

Again, consider what constitutes "a long lens". It is "narrow angle of view"
by what appears to be your definition, but this definition is incorrect since
it does not specify the FL *and* the sensor size - and a lens FL that is a
"long lens" on one format can be a "super-wide lens" (with "distortion",
as with a 90mm f5.6 Nikkor on 8x10, and the same lens used for 35mm)
on another format.

>> It is because of these differences in perspective that are unique to
>> wide-angle lenses that we can immediately tell a wide-angle picture when we
>> see one. If those important differences in perspective were not there, we
>> would not be able to tell a wide-angle picture from a normal or long-lens
>> one.

These are differences in "angle of view" [YEAH!!! Judge Williams has just
followed up his ruling declaring Prop. 8 in California unconstitutional with
a judgment that his own stay on implementation will be of very limited
duration. BTW, NH was ***TOTALLY*** and irrationally opposed
to this, as he also was on the issue of Health Reform. Talk about a "stick
in the mud"...! ;-], not differences in perspective, and differences would
also be seen for all perspective types with increased angle of view.

> 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"...;-)

> 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.
--DR


From: Neil Harrington on

"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. :-)


From: Peter on
"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.


--
Peter

From: Paul Furman on
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! :-)
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.
From: Neil Harrington on

"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.