From: David Ruether on

"David Ruether" <d_ruether(a)thotmail.com> wrote in message
news:i2k3ml$8ac$1(a)ruby.cit.cornell.edu...
> "Bruce" <docnews2011(a)gmail.com> wrote in message
> news:5k2r46pe2t2t7tsjn802pa3o5v7lla946f(a)4ax.com...
>> On Mon, 26 Jul 2010 09:10:02 -0400, "David Ruether"
>> <d_ruether(a)thotmail.com> wrote:
>>>"Ryan McGinnis" <digicana(a)gmail.com> wrote in message
>>>news:4c4d0899$0$24965$c3e8da3(a)news.astraweb.com...

>>>> I love ultrawide, don't get me wrong -- but it's not some magic type of
>>>> lens where you can point it at anything and come out with a great photo.
>>>> I think photographers who are more drawn to lines and shapes and
>>>> symmetry tend to love ultrawide, and people who love lines and shapes
>>>> will find those kinds of lenses to be astoundingly intuitive to compose
>>>> with. But anecdotally, I've also known photographers who are less
>>>> interested in lines and shapes and are heavily annoyed by the necessary
>>>> distortion of ultrawide and thus are a bit lost in figuring out how to
>>>> compose a shot in ultrawide.
>>>> - --
>>>> - -Ryan McGinnis

>>>I second this...;-) With the exception, of course, of the use of the word
>>>"distortion" here - I think substituting "unfamiliar perspective imaging
>>>characteristics" in the above is more accurate and less misleading...;-)
>>>There is true lens distortion (the failure of a lens to follow accurately the
>>>perspective type of the lens), but this is not it. Confusing the two does
>>>not help.

>> It also doesn't help when people associate perspective with the lens's
>> focal length. Perspective is purely a function of viewpoint and its
>> relationship with the subject. The focal length of the lens is
>> irrelevant.

> Correct, and a good point. Also, associating "WA distortion" etc. with
> specific FLs can result in odd results, as in a rectangular-perspective
> 10mm can be a super-wide on some formats (with the associated
> "distortions" ;-), and it can also be a "distortionless" long FL on other
> formats. 'Course, a rotating-slit camera or a stitched digital panorama
> with their altered effective sensor shapes can also affect the perspective
> type of the system (in this case, the perspective type is "cylindrical").
> Understanding perspective can be fun! 8^)
> --DR

Ooops! I let slip by, "Perspective is purely a function of viewpoint and
its relationship with the subject." "Perspective" is also a function of the
specific perspective type the lens/sensor-shape renders when making
the image...
--DR


From: Twibil on
Have paint brushes become cliched for painting things?

(Hint: It's a tool. And like all tools it doesn't tell you how to use
it. You could paint like Monet or you could paint a house.)

Same tool.
From: Chris Malcolm on
In rec.photo.digital David Ruether <d_ruether(a)thotmail.com> wrote:

> "Ryan McGinnis" <digicana(a)gmail.com> wrote in message
> news:4c4d0899$0$24965$c3e8da3(a)news.astraweb.com...

>> I love ultrawide, don't get me wrong -- but it's not some magic type of
>> lens where you can point it at anything and come out with a great photo.
>> I think photographers who are more drawn to lines and shapes and
>> symmetry tend to love ultrawide, and people who love lines and shapes
>> will find those kinds of lenses to be astoundingly intuitive to compose
>> with. But anecdotally, I've also known photographers who are less
>> interested in lines and shapes and are heavily annoyed by the necessary
>> distortion of ultrawide and thus are a bit lost in figuring out how to
>> compose a shot in ultrawide.

> I second this...;-) With the exception, of course, of the use of the word
> "distortion" here - I think substituting "unfamiliar perspective imaging
> characteristics" in the above is more accurate and less misleading...;-)
> There is true lens distortion (the failure of a lens to follow accurately the
> perspective type of the lens), but this is not it. Confusing the two does
> not help.

I've been wondering for some time how to describe that popularly
miconceived "wide angle distortion" of a wide angle rectilinear
lens. Your "unfamiliar perspective imaging characteristics" is
excellent!

Since that "unfamiliar perspective imaging characteristic" is exactly
what would be produced by a pinhole camera with no lens at all, and
can simply be removed by moving your eye close enough to the print to
recreate the camera's angle of view, I've never liked the idea of
calling it "distortion".

--
Chris Malcolm
Warning: none of the above is indisputable fact.
From: David Ruether on

"Chris Malcolm" <cam(a)holyrood.ed.ac.uk> wrote in message
news:8ba487FkkU2(a)mid.individual.net...
> In rec.photo.digital David Ruether <d_ruether(a)thotmail.com> wrote:
>> "Ryan McGinnis" <digicana(a)gmail.com> wrote in message
>> news:4c4d0899$0$24965$c3e8da3(a)news.astraweb.com...

>>> I love ultrawide, don't get me wrong -- but it's not some magic type of
>>> lens where you can point it at anything and come out with a great photo.
>>> I think photographers who are more drawn to lines and shapes and
>>> symmetry tend to love ultrawide, and people who love lines and shapes
>>> will find those kinds of lenses to be astoundingly intuitive to compose
>>> with. But anecdotally, I've also known photographers who are less
>>> interested in lines and shapes and are heavily annoyed by the necessary
>>> distortion of ultrawide and thus are a bit lost in figuring out how to
>>> compose a shot in ultrawide.

>> I second this...;-) With the exception, of course, of the use of the word
>> "distortion" here - I think substituting "unfamiliar perspective imaging
>> characteristics" in the above is more accurate and less misleading...;-)
>> There is true lens distortion (the failure of a lens to follow accurately the
>> perspective type of the lens), but this is not it. Confusing the two does
>> not help.

> I've been wondering for some time how to describe that popularly
> miconceived "wide angle distortion" of a wide angle rectilinear
> lens. Your "unfamiliar perspective imaging characteristics" is
> excellent!
>
> Since that "unfamiliar perspective imaging characteristic" is exactly
> what would be produced by a pinhole camera with no lens at all, and
> can simply be removed by moving your eye close enough to the print to
> recreate the camera's angle of view, I've never liked the idea of
> calling it "distortion".
> --
> Chris Malcolm

Ah, I like your example for showing why super-wide rectangular
perspective images are not "distorted" (accomplished by replacing
familiar "reality" with the "distorted" images under the appropriate
conditions and then finding no appreciable differences in the views...;-).
So much of this is simply logical! ;-)
--DR


From: David Ruether on

"David Ruether" <d_ruether(a)thotmail.com> wrote in message
news:i2pjoa$m58$1(a)ruby.cit.cornell.edu...
> "Chris Malcolm" <cam(a)holyrood.ed.ac.uk> wrote in message
> news:8ba487FkkU2(a)mid.individual.net...
>> In rec.photo.digital David Ruether <d_ruether(a)thotmail.com> wrote:
>>> "Ryan McGinnis" <digicana(a)gmail.com> wrote in message
>>> news:4c4d0899$0$24965$c3e8da3(a)news.astraweb.com...

>>>> I love ultrawide, don't get me wrong -- but it's not some magic type of
>>>> lens where you can point it at anything and come out with a great photo.
>>>> I think photographers who are more drawn to lines and shapes and
>>>> symmetry tend to love ultrawide, and people who love lines and shapes
>>>> will find those kinds of lenses to be astoundingly intuitive to compose
>>>> with. But anecdotally, I've also known photographers who are less
>>>> interested in lines and shapes and are heavily annoyed by the necessary
>>>> distortion of ultrawide and thus are a bit lost in figuring out how to
>>>> compose a shot in ultrawide.

>>> I second this...;-) With the exception, of course, of the use of the word
>>> "distortion" here - I think substituting "unfamiliar perspective imaging
>>> characteristics" in the above is more accurate and less misleading...;-)
>>> There is true lens distortion (the failure of a lens to follow accurately the
>>> perspective type of the lens), but this is not it. Confusing the two does
>>> not help.

>> I've been wondering for some time how to describe that popularly
>> miconceived "wide angle distortion" of a wide angle rectilinear
>> lens. Your "unfamiliar perspective imaging characteristics" is
>> excellent!
>>
>> Since that "unfamiliar perspective imaging characteristic" is exactly
>> what would be produced by a pinhole camera with no lens at all, and
>> can simply be removed by moving your eye close enough to the print to
>> recreate the camera's angle of view, I've never liked the idea of
>> calling it "distortion".
>> --
>> Chris Malcolm

> Ah, I like your example for showing why super-wide rectangular
> perspective images are not "distorted" (accomplished by replacing
> familiar "reality" with the "distorted" images under the appropriate
> conditions and then finding no appreciable differences in the views...;-).
> So much of this is simply logical! ;-)
> --DR

Ah, a bit more to add to the above... If a "distorted" fisheye photo is
projected onto a hemispherical surface and the eye is placed properly
at the center of the circle at the hemisphere's rear, the view will also
be undistorted, and an angle of view that is impossible to achieve with
rectangular perspective can easily be achieved with the fisheye view.
--DR


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