50mm pictures with D300

"Chris Malcolm" <cam.RemoveThis@holyrood.ed.ac.uk> wrote in message
news:5vr9j3F1nj4fmU1@mid.individual.net...
> > Which is why photographers have long understood that wide angle lenses
do
> > not generally make for good portraits, given that a persons face is not
a
> > flat plane
>
> A room interior or a table top isn't a flat plane either, but we
> nevertheless consider that natural views of them require lenses of
> shorter focal lengths than the canonical facial portrait lenses.

No, we simply accept thats what we get if we want to get everything in
without knocking down walls.
Neither case is any more "correct" than the other from a visual point of
view. One will be far more accurate if we were to attempt to make
measurements from the photo. That will not be the wide angle view!

> The more general photographic point is that what we consider a natural
> perspective of something is the combination of distance and angle of
> view at which we most usually look at it carefully and from which we
> form our canonical impressions of what it looks like.

Agreed, but the brain usually does a good job of reinterpreting what the eye
"sees" to match our experience/expectations in any case.

MrT.
 >> Stay informed about: 50mm pictures with D300 

"Dudley Hanks" <hanks.dudley.DeleteThis@gmail.com> wrote in message
news:rdwlj.13670$vp3.2574@edtnps90...
>
> "John Navas" <spamfilter1.DeleteThis@navasgroup.com> wrote in message
> news:a0ucp3tdk76b6j5e102b7ajbusua4ph1gd@4ax.com...
>> On Tue, 22 Jan 2008 18:03:52 -0500, "Rita Berkowitz"
>> <ritaberk2008.DeleteThis@aol.com> wrote in <13pctna5kusdia2.DeleteThis@news.supernews.com>:
>>
>>>Sosumi wrote:
>>>
>>>> I've seen people take amazing good pictures with a simple camera,
>>>> without any other than standard lenses. How else would they zoom
>>>> other then with their feet?
>>>> Portrait or landscape orientation is also done by hand, not by lens.
>>>> Big part of the framing.
>>>
>>>LOL! Amazing, isn't it? Some people just don't get it.
>>
>> Indeed we don't. We use the correct focal length for the best possible
>> image based on such things as composition and perspective; i.e., we
>> don't spoil the image by using the wrong focal length.
>>
>> "If all you have is a hammer, everything looks like a nail."
>>
>> --
>> Best regards,
>> John Navas
>> Panasonic DMC-FZ8 (and several others)
>
> John, for such a good photographer, you seem to spend more time in front
> of your computer than behind your eyepiece.
>
> Why is that?
>
> Curious,
> Dudley
>
I'd be more curious as to why a seasoned photographer calls a veiwfinder an
eyepiece
 >> Stay informed about: 50mm pictures with D300 

In rec.photo.digital.slr-systems John Navas <spamfilter1.DeleteThis@navasgroup.com> wrote:
> On 23 Jan 2008 11:21:49 GMT, Chris Malcolm <cam.DeleteThis@holyrood.ed.ac.uk> wrote
> in <5vomadF1n8mvjU1.DeleteThis@mid.individual.net>:

>>That is exactly my point. The perspective of an image has to with the
>>relationships between all of the things in the entire image. That is
>>determined by three things, the position of the camera, where it's
>>pointing, and the subtended angle of view.

> Perspective is simply the relationship of objects closer and farther
> away; i.e., at different distances. It's why objects farther away look
> smaller, and how much smaller is what perspective is all about. It is
> not the overall image and/or the angle of view.

> <http://www.dpreview.com/learn/?/Glossary/Optical/Perspective_01.htm>

> If you photograph a subject with a tele lens and want it to have the
> same size on the film or sensor when photographing it with a wide
> angle lens, you would have to move closer to the subject. Because
> this would cause the perspective to change, lenses with different
> focal lengths are said to "have" a different perspective. Note
> however that changing the focal length without changing the subject
> distance will not change perspective, ...

>>Note that I said "position"
>>of the camera. That determines its spatial relationship to everything
>>in the image. "Distance to subject" doesn't work when the subject has
>>no clearly identifiable distance or is multiple.

> There is always a subject.

But it doesn't always have a clearly identifiable distance. Consider
for example standing beneath a long cliff and photographing along its
length. The subject is the cliff receding into the distance. The
distance of the nearest part of the cliff at the edge of the image is
six feet. The distance of the furthest part is several miles.

What is the distance to the subject in this case?

Now walk forwards six feet. How has the distance to the subject changed?

Now change focal length from 24mm (35mm film equiv) to 100mm. The
distance to the nearest part of the cliff in the image has changed a
lot. The image also looks quite different. What is more you couldn't
walk forwards with the 24mm lens to get the same view of the cliff as
the 100mm lens did. Are you claiming that it is wrong to say that the
the perspective of the subject is different in these two images taken
from the same position with two different focal lengths?

I suspect you are, by your argument that a central crop of the 24mm
image will look the same as the 100mm image and therefore be the same
perspective. I agree that it would. So now let's now consider that
argument.

>>The three necessary and sufficient determinants of simple rectilinear
>>image perspective are position, direction of view, and subtended angle
>>of view.

> These things have nothing to do with perspective.

> The simple test is to photograph the same portrait with a wide angle
> lens and with a telephoto lens at the same image magnification
> (different subject distance), and note the difference in perspective
> (e.g., enlarged nose in the wide angle shot). When photographed at the
> same distance and cropped to match, the images and thus the perspective
> are identical. Again, you simply cannot change perspective without
> changing distance to subject, nohow, noway.

By centering your crop around the central axis of the viewing
direction that test has conveniently cropped off the parts where the
change in perspective is evident. If you crop to the left hand half of
the wider image, and then with twice the focal length swing round to
encompass the same view as the crop, you will get two different
looking images. What would you call those differences? I would call
them differences in perspective. And if there were any aids to judging
the perspective projection in the image, such as people and buildings
as in a street scene, then there would be something disinctly odd
looking about the perspective of the side cropped image. Yet the
photographer hasn't changed position. All distances remain the
same. All that has been changed is focal length and direction of view.

These differences are not as some have claimed distortion effects of
lenses because they're equally evident if you do the same thing with a
pinhole camera. And if you want to make two accurate perspective
sketches of the view using the theory of perspective projection as
elaborated by Renaissance painters with rulers, vanishing points,
etc., you would change the kind of perspective projection you were
doing to get the differences between the two images. Similarly if you
had a three dimensional model of the scene in a computer and wanted to
generate those two different images you would choose different
perspective projection parameters.

My definition of a difference in perspective between two images is
having to make a change in the perspective projection parameters to
generate the difference. And any change between two images generated
soley by a change of perspective projection I would call a change in
perspective.

That seems to me to be a logical definition, which could be made
formally mathematical in terms of the theory of perspective
projection, and which seems to be reasonably consistent with popular
uses of the term "perspective" as it applies to paintings and
photographs.

--
Chris Malcolm cam.DeleteThis@infirmatics.ed.ac.uk DoD #205
IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
[http://www.dai.ed.ac.uk/homes/cam/]
 >> Stay informed about: 50mm pictures with D300 

"Wilba" <wilba.TakeThisOut@CUTTHISimago.com.au> wrote in message
news:fna09f$bqm$1@news-01.bur.connect.com.au...
> > Actually no, the eye still sees the same converging lines, it's just
that
> > the brain is used to interpreting it as experience tells it to.
>
> Try tracing on a pane of glass a scene which contains convergent lines.
Then
> tilt the pane. The lines on the glass now converge on a different
vanishing
> point to the lines in the scene.

Sorry, badly worded on my part. I did not mean the convergence would always
appear constant to the eye, I meant the same as the camera.
If you change the angle, then both will "see" a different convergence point.

MrT.
 >> Stay informed about: 50mm pictures with D300 

Mr.T wrote:
> Wilba wrote:
>> Mr.T wrote:
>>>
>>> Actually no, the eye still sees the same converging lines, it's just
>>> that the brain is used to interpreting it as experience tells it to.
>>
>> Try tracing on a pane of glass a scene which contains convergent
>> lines. Then tilt the pane. The lines on the glass now converge on a
>> different vanishing point to the lines in the scene.
>
> Sorry, badly worded on my part. I did not mean the convergence
> would always appear constant to the eye, I meant the same as the
> camera. If you change the angle, then both will "see" a different
> convergence point.

No, the eye will still see what it always sees. That's the point.
 >> Stay informed about: 50mm pictures with D300 

"Wilba" <wilba DeleteThis @CUTTHISimago.com.au> wrote in message
news:fnbskh$622$1@news-01.bur.connect.com.au...
> > Sorry, badly worded on my part. I did not mean the convergence
> > would always appear constant to the eye, I meant the same as the
> > camera. If you change the angle, then both will "see" a different
> > convergence point.
>
> No, the eye will still see what it always sees.

Exactly, the eye "sees" what's there to be seen, but the brain does the
interpretation.

>That's the point.

Which is?

Seems like maybe just another pointless argument over semantics and
linguistics? Or do you not believe the brain often mis-interprets data being
fed to it by our senses? I suggest a trip to Questicon in the ACT, will
clearly demonstrate otherwise.

MrT.
 >> Stay informed about: 50mm pictures with D300 

"Chris Malcolm" <cam RemoveThis @holyrood.ed.ac.uk> wrote in message
news:5vu07dF1o64btU1@mid.individual.net...
> In rec.photo.digital.slr-systems John Navas <spamfilter1 RemoveThis @navasgroup.com>
> wrote:
>> On 23 Jan 2008 11:21:49 GMT, Chris Malcolm <cam RemoveThis @holyrood.ed.ac.uk> wrote
>> in <5vomadF1n8mvjU1 RemoveThis @mid.individual.net>:
>
>>>That is exactly my point. The perspective of an image has to with the
>>>relationships between all of the things in the entire image. That is
>>>determined by three things, the position of the camera, where it's
>>>pointing, and the subtended angle of view.
>
>> Perspective is simply the relationship of objects closer and farther
>> away; i.e., at different distances. It's why objects farther away look
>> smaller, and how much smaller is what perspective is all about. It is
>> not the overall image and/or the angle of view.
>
>> <http://www.dpreview.com/learn/?/Glossary/Optical/Perspective_01.htm>
>
>> If you photograph a subject with a tele lens and want it to have the
>> same size on the film or sensor when photographing it with a wide
>> angle lens, you would have to move closer to the subject. Because
>> this would cause the perspective to change, lenses with different
>> focal lengths are said to "have" a different perspective. Note
>> however that changing the focal length without changing the subject
>> distance will not change perspective, ...
>
>>>Note that I said "position"
>>>of the camera. That determines its spatial relationship to everything
>>>in the image. "Distance to subject" doesn't work when the subject has
>>>no clearly identifiable distance or is multiple.
>
>> There is always a subject.
>
> But it doesn't always have a clearly identifiable distance. Consider
> for example standing beneath a long cliff and photographing along its
> length. The subject is the cliff receding into the distance. The
> distance of the nearest part of the cliff at the edge of the image is
> six feet. The distance of the furthest part is several miles.
>
> What is the distance to the subject in this case?
>
> Now walk forwards six feet. How has the distance to the subject changed?
>
> Now change focal length from 24mm (35mm film equiv) to 100mm. The
> distance to the nearest part of the cliff in the image has changed a
> lot. The image also looks quite different. What is more you couldn't
> walk forwards with the 24mm lens to get the same view of the cliff as
> the 100mm lens did. Are you claiming that it is wrong to say that the
> the perspective of the subject is different in these two images taken
> from the same position with two different focal lengths?
>
> I suspect you are, by your argument that a central crop of the 24mm
> image will look the same as the 100mm image and therefore be the same
> perspective. I agree that it would. So now let's now consider that
> argument.
>
>>>The three necessary and sufficient determinants of simple rectilinear
>>>image perspective are position, direction of view, and subtended angle
>>>of view.
>
>> These things have nothing to do with perspective.
>
>> The simple test is to photograph the same portrait with a wide angle
>> lens and with a telephoto lens at the same image magnification
>> (different subject distance), and note the difference in perspective
>> (e.g., enlarged nose in the wide angle shot). When photographed at the
>> same distance and cropped to match, the images and thus the perspective
>> are identical. Again, you simply cannot change perspective without
>> changing distance to subject, nohow, noway.
>
> By centering your crop around the central axis of the viewing
> direction that test has conveniently cropped off the parts where the
> change in perspective is evident. If you crop to the left hand half of
> the wider image, and then with twice the focal length swing round to
> encompass the same view as the crop, you will get two different
> looking images. What would you call those differences? I would call
> them differences in perspective. And if there were any aids to judging
> the perspective projection in the image, such as people and buildings
> as in a street scene, then there would be something disinctly odd
> looking about the perspective of the side cropped image. Yet the
> photographer hasn't changed position. All distances remain the
> same. All that has been changed is focal length and direction of view.
>
> These differences are not as some have claimed distortion effects of
> lenses because they're equally evident if you do the same thing with a
> pinhole camera. And if you want to make two accurate perspective
> sketches of the view using the theory of perspective projection as
> elaborated by Renaissance painters with rulers, vanishing points,
> etc., you would change the kind of perspective projection you were
> doing to get the differences between the two images. Similarly if you
> had a three dimensional model of the scene in a computer and wanted to
> generate those two different images you would choose different
> perspective projection parameters.
>
> My definition of a difference in perspective between two images is
> having to make a change in the perspective projection parameters to
> generate the difference. And any change between two images generated
> soley by a change of perspective projection I would call a change in
> perspective.
>
> That seems to me to be a logical definition, which could be made
> formally mathematical in terms of the theory of perspective
> projection, and which seems to be reasonably consistent with popular
> uses of the term "perspective" as it applies to paintings and
> photographs.
>
> --
> Chris Malcolm cam RemoveThis @infirmatics.ed.ac.uk DoD #205
> IPAB, Informatics, JCMB, King's Buildings, Edinburgh, EH9 3JZ, UK
> [http://www.dai.ed.ac.uk/homes/cam/]

Exactly!

Impressed,
Dudley
 >> Stay informed about: 50mm pictures with D300 

>> Perspective is simply the relationship of objects closer and farther
>> away; i.e., at different distances. It's why objects farther away look
>> smaller, and how much smaller is what perspective is all about. It is
>> not the overall image and/or the angle of view.

You are refering to linear perspective here. And, there is more to it than
simply judging the size of objects.By your criteria, size is the only
indicator of distance, but what about atmospheric defraction, dispertion of
reflected light, overlapping objects, etc. If all we do is look at relative
size and then judge perspective, we wouldn't be able to come up with a shot
where two objects that look the same in the final print were actually at
different distances in the original scene. Your criteria for judging
perspective is too strict.

>
>> If you photograph a subject with a tele lens and want it to have the
>> same size on the film or sensor when photographing it with a wide
>> angle lens, you would have to move closer to the subject. Because
>> this would cause the perspective to change, lenses with different
>> focal lengths are said to "have" a different perspective. Note
>> however that changing the focal length without changing the subject
>> distance will not change perspective, ...

If we arbitrarily start with the axiom that perspective is simply the visual
affect of receding distance, then it would be hard to describe the effect
produced by capturing an identical scene with differing focal lengths. In
my opinion, one can only describe it in terms of perspective. "Distortion"
just doesn't work because the lens is not distorting the scene, it is simply
capturing it from a distinct rectilinear perspective.


Making Progress,
Dudley
 >> Stay informed about: 50mm pictures with D300 

Dudley Hanks wrote:
>>> Perspective is simply the relationship of objects closer and
>>> farther away; i.e., at different distances. It's why objects
>>> farther away look smaller, and how much smaller is what
>>> perspective is all about. It is not the overall image and/or the
>>> angle of view.
>
> You are refering to linear perspective here. And, there is more to
> it than simply judging the size of objects.By your criteria, size
> is the only indicator of distance, but what about atmospheric
> defraction, dispertion of reflected light, overlapping objects,
> etc. If all we do is look at relative size and then judge
> perspective, we wouldn't be able to come up with a shot where two
> objects that look the same in the final print were actually at
> different distances in the original scene. Your criteria for
> judging perspective is too strict.
>>
>>> If you photograph a subject with a tele lens and want it to
>>> have the same size on the film or sensor when photographing it
>>> with a wide angle lens, you would have to move closer to the
>>> subject. Because this would cause the perspective to change,
>>> lenses with different focal lengths are said to "have" a
>>> different perspective. Note however that changing the focal
>>> length without changing the subject distance will not change
>>> perspective, ...
>
> If we arbitrarily start with the axiom that perspective is simply
> the visual affect of receding distance, then it would be hard to
> describe the effect produced by capturing an identical scene with
> differing focal lengths. In my opinion, one can only describe it
> in terms of perspective. "Distortion" just doesn't work because
> the lens is not distorting the scene, it is simply capturing it
> from a distinct rectilinear perspective.
>
> Making Progress,
> Dudley

See if anyone can use these (pretty much) identical clunky push-button
panorama scenes, with differing focal lengths (17mm, 24mm, 40mm) as
the only variable, to explain what perspective /is/:

http://www.fototime.com/A4CECDE04F5A685/orig.jpg 230+K
http://www.fototime.com/A2C833A82101208/orig.jpg 290+K
http://www.fototime.com/05118D3A08195E9/orig.jpg 420+K

I think there are enough meanings of perspective that each should have
a new term to designate that instance in that context, something like
"bokeh" has been adapted and adopted to describe something a number of
previously vague or esoteric terms attempted to do for what is a real
effect.

--
Frank ess
 >> Stay informed about: 50mm pictures with D300 

>>>>>>Now, to mess with your mind just a bit more, what would you say, John,
>>>>>>if
>>>>>>I told you I was taking part in a sociology experiment conducted by
>>>>>>the
>>>>>>Department of Justice, with the aim of trying to determine whether or
>>>>>>not
>>>>>>blind computer users are being discriminated against in their daily
>>>>>>net
>>>>>>activities, and that pending computer regulations could depend on what
>>>>>>you
>>>>>>have said already, and on how your react in the future?
>>>>>
>>>>> More BS.
>>>
>>>>Whether it is or isn't, this type of study will happen, if it isn't
>>>>already.
>>>>And, you, my friend, will surely have some unwanted visiters.
>>>
>>> More BS. And sad empty threats.
>>>
>>> --
>>> Best regards,
>>> John Navas
>>> Panasonic DMC-FZ8 (and several others)
>>
John, it is just too easy to mess with you.

I start by telling you that I'm just messing with your mind, and you come
back with "empty threats"?

How can messing with your mind be a threat? (Maybe you really believed me?)
AHAHAHA... AHAHAHA... AHA... HA... HA...
(That sounds sooo funny when heard through a screen reader!)

Laughing,
Dudley
 >> Stay informed about: 50mm pictures with D300 

Mr.T wrote:
> Wilba wrote:

>>> Sorry, badly worded on my part. I did not mean the convergence
>>> would always appear constant to the eye, I meant the same as the
>>> camera. If you change the angle, then both will "see" a different
>>> convergence point.
>>
>> No, the eye will still see what it always sees.
>
> Exactly, the eye "sees" what's there to be seen, but the brain does the
> interpretation.

That's irrelevant to the context, which you have removed.

>> That's the point.
>
> Which is?

The perspective of the eye (regardless of interpretation by the brain) is
not the same as the perspective of an image, once that image is tilted.

What do you see when you do this?

>>>> Try tracing on a pane of glass a scene which contains convergent
>>>> lines. Then tilt the pane. The lines on the glass now converge on a
>>>> different vanishing point to the lines in the scene.

> Seems like maybe just another pointless argument over semantics and
> linguistics? Or do you not believe the brain often mis-interprets data
> being fed to it by our senses? I suggest a trip to Questicon in the ACT,
> will clearly demonstrate otherwise.

Since you're talking about stuff that has nothing to do with what I'm
talking about, I have to assume that you don't know what I'm talking about.


Try the above (yeah, actually do it), and let me know what you find.
 >> Stay informed about: 50mm pictures with D300 

"Dudley Hanks" <hanks.dudley RemoveThis @gmail.com> wrote
news:7Trmj.28478$yQ1.16965@edtnps89...
>
>.................................................
>
> Exactly!
>
> Impressed,
> Dudley


Nothing like quoting a hundred lines of message across four newsgroups to
say "exactly"
Fer chrissakes..............
 >> Stay informed about: 50mm pictures with D300 

"Frank ess" <frank.DeleteThis@fshe2fs.com> wrote in message
news:fNydnXnz7NAwyAfanZ2dnUVZ_q-jnZ2d@giganews.com...
>
>
> Dudley Hanks wrote:
>>>> Perspective is simply the relationship of objects closer and
>>>> farther away; i.e., at different distances. It's why objects
>>>> farther away look smaller, and how much smaller is what
>>>> perspective is all about. It is not the overall image and/or the
>>>> angle of view.
>>
>> You are refering to linear perspective here. And, there is more to
>> it than simply judging the size of objects.By your criteria, size
>> is the only indicator of distance, but what about atmospheric
>> defraction, dispertion of reflected light, overlapping objects,
>> etc.

>>>
>>>> If you photograph a subject with a tele lens and want it to
>>>> have the same size on the film or sensor when photographing it
>>>> with a wide angle lens, you would have to move closer to the
>>>> subject. Because this would cause the perspective to change,
>>>> lenses with different focal lengths are said to "have" a
>>>> different perspective. Note however that changing the focal
>>>> length without changing the subject distance will not change
>>>> perspective, ...
>>
>> If we arbitrarily start with the axiom that perspective is simply
>> the visual affect of receding distance, then it would be hard to
>> describe the effect produced by capturing an identical scene with
>> differing focal lengths. In my opinion, one can only describe it
>> in terms of perspective. "Distortion" just doesn't work because
>> the lens is not distorting the scene, it is simply capturing it
>> from a distinct rectilinear perspective -- ie. from a perspective with
>> a narrower angle of view.

If we choose to stict with the perspective equals distance formula, what
term do we use to describe this affect? Angular Compression? Focal-length
Variance? I doubt these terms will catch on... They just don't do the job.


>> Making Progress,
>> Dudley
>
> See if anyone can use these (pretty much) identical clunky push-button
> panorama scenes, with differing focal lengths (17mm, 24mm, 40mm) as the
> only variable, to explain what perspective /is/:
>
> http://www.fototime.com/A4CECDE04F5A685/orig.jpg 230+K
> http://www.fototime.com/A2C833A82101208/orig.jpg 290+K
> http://www.fototime.com/05118D3A08195E9/orig.jpg 420+K
>
> I think there are enough meanings of perspective that each should have a
> new term to designate that instance in that context, something like
> "bokeh" has been adapted and adopted to describe something a number of
> previously vague or esoteric terms attempted to do for what is a real
> effect.
>
> --
> Frank ess

And, what would happen if we through in 100mm, 200mm and 300mm as further
test shots?

It seems that we already do have some differing terms, such as rectilinear
perspective, linear perspective, fish-eye perspectiveand panorama
perspective, but people aren't using them, nor taking the time to understand
the difference.

Do we have enough terms to cover the multitude of rhetorical permutations?
I doubt it. But, at least, we can start by trying to sort out the
differences in the terms we have, and then see if we need more.

What do you think?
Dudley
 >> Stay informed about: 50mm pictures with D300