perspective vs. field of view

Roger Hicks said:
Another way of looking at it is this:

You make a 20x30cm (8x12 inch) enlargement from the full frame, and physically remove the bit that isn't covered by the smaller sensor. Result: identical perspective, but less stuff around the edges. With a 1.5x multiplication factor, 16x24mm sensor, you'd have cut the picture down to roughly 13x20cm (5x8 inch).

If you then had a perfect photocopier, and could enlarge this print to 20x30cm, and looked at the new print from the same viewing distance as the old, the perspective wouldn't look the same.

Cheers,

R.
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Correct, and that is why we speak of Field of View. A Planar 135mm lens over 4x5 will contain a section equivalent to 35mm, but the section of 35mm has a 'compressed' view, a narrow FOV.
 
Turning to Kingslake, there is "True Perspective and Apparent Perspective".

As per Kingslake, "Lenses in Photography", 1951,

True Perspective is fixed solely by the Position of the Camera. The lens used and format used does not change true perspective.

Apparent Perspective is set by moving the eye relative to the finished print.

Newcombe, "35-mm Photo Technique", 1948, states that perspective is solely dependent on camera position at the time of making the exposure, and nothing else. This definition agrees with Kingslake's "True Perspective".

SO: according to Rudolf Kingslake and H.S Newcombe, the position of the camera at the time of exposure sets the true perspective of the image. Focal length and Frame format have nothing to do with it.

To test this statement, cut the back off of your RD-1, yank out the Sensor, and put ground glass in its place. Then open the back of the Canon P, open the shutter, and put ground glass at the film plane. You will see that the true perspective of the 35mm lens does not change it as you move it from the RD-1 to the Canon P.
 
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Dear Brian,

In a photograph, the dichotomy between 'true perspective' and 'apparent perspective' is completely false.

Perspective is a psychological construct, loosely based in physics (and not, pace the other Brian, a 'fact' in the sense of something verifiable other than by consensus). There is only one sort of perspective in photography, and it's apparent perspective. One can argue the same for 'real life' as well, but I'm disinclined to try.

Cheers,

R.
 
I merely quote from reliable sources. If such experts as Kingslake makes the cited statement, it has some credibility. It also explains the confusion regarding the matter. Look in Webster's, there are 5 accepted definitions for the word "perspective". The definitions given in the cited sources falls within those accepted.
 
So: as you come to the bridge, and the Troll asks "does perspective change with focal length on a given camera?" ask him if he means "True or Apparent Perspective?"

Monty Python chose average speed of the Swallow instead.
 
Dear Brian,

There's a bit of a difference between someone writing about optics and making a brief aside about perspective, and someone researching the psychology of vision: Richard Gregory, for example (The Intelligent Eye, Eye and Brain).

Cheers,

R.
 
Roger Hicks said:
Dear Brian,

There's a bit of a difference between someone writing about optics and making a brief aside about perspective, and someone researching the psychology of vision: Richard Gregory, for example (The Intelligent Eye, Eye and Brain).

Cheers,

R.
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One would have an optics/physics bias, the other, a psychology bias.
 
zumbido said:
The essence of "perspective" is that--to human vision--objects have a varying appearance based on, at least, distance and angle of view. Setting aside the various debates here, that's as verifiable as anything else in a non-solipsistic world.

Now, using these "facts" to create or distort perspective trades in psychology (and/or neurobiology but that's another debate), and your position is that this is the only thing that's relevant in photography. I somewhat disagree, but only somewhat, in that the mathematical perspective of the naked eye is the starting point from which the lens then departs--because, of course, both the composing and the viewing of the image are done with that same naked eye.
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Dea Brian,

As you say, we only disagree somewhat -- though in addition, I argue for other perspective clues, some of which may be learned or culturally determined.

Cheers,

R.
 
Roger Hicks said:
Dear Brian,
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Roger Hicks said:
In a photograph, the dichotomy between 'true perspective' and 'apparent perspective' is completely false.

Perspective is a psychological construct, loosely based in physics (and not, pace the other Brian, a 'fact' in the sense of something verifiable other than by consensus). There is only one sort of perspective in photography, and it's apparent perspective. One can argue the same for 'real life' as well, but I'm disinclined to try.

Cheers,

R.
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If I understand you correctly, because perspective is psychological, when Back Alley takes a 35mm lens and mounts it on a 'crop' sensor, he'll achieve a different FOV, but whether he senses a change in perspective will depend on what he’s shooting in a scene and his position vis-à-vis the elements in that scene.
 
For a discussion such as this to continue without the participants talking past each other, they must agree on what they are discussing.

I suspect most are discussing what has been cited as "apparent perspective". That subject is much like depth of field, and depends on scene content and the position of the viewer. So, a white wall with infinite height and width will not undergo an apparent change of perspective depending on focal length and frame format used to image it.
 
Brian Sweeney said:
For a discussion such as this to continue without the participants talking past each other, they must agree on what they are discussing.

I suspect most are discussing what has been cited as "apparent perspective". That subject is much like depth of field, and depends on scene content and the position of the viewer. So, a white wall with infinite height and width will not undergo an apparent change of perspective depending on focal length and frame format used to image it.
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Come on, Brian. If you're going to start defining terms, you really ought to say an evenly illuminated, textureless white wall of infinite height and width.

Seriously, my point from the very beginning has been to try to point out that as soon as anyone tries to define perspective in strictly mathematical terms, they are ignoring what people actually see, i.e. there are other clues. Very much, as you say, like depth of field. This is why I sometimes have a problem with those who USE CAPITALS to say that ONLY this, that or the other defines perspective.

Cheers,

R.
 
Roger Hicks said:
Come on, Brian. If you're going to start defining terms, you really ought to say an evenly illuminated, textureless white wall of infinite height and width.
Cheers,

R.
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I stand corrected, you are 100% right!

I never care how trivial a statement might be, as long as it is .TRUE.

And- given a choice between cutting a hole in his RD-1 required to test true perspective, I am sure the OP will prefer the discussion about apparent perspective. Take a picture with the RD-1 and Canon P, both using the same lens, of the same object, from the same position. Enlarge them to the same size, position them in front of his eye so that they look right. Measure how far away from his eye that he had to hold them so that they look correct. I just got a mental image of Dr. Tongue's House of Three-D Cats.

I write all of my FORTRAN code using the caps lock. Holdover from FORTRAN-66 days. I use mixed case in Assembly.
 
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tiny1.jpg


I've long thought that this image has a
strange perspective. Something about
blank space being the subject.
 
Ah, negative space as part of the composition. (Though I don't see that in your example, Pico.)
 
Pico said:
tiny1.jpg


I've long thought that this image has a
strange perspective. Something about
blank space being the subject.
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You're right. It does. And I think your analysis is correct too.

The more you think about perspective, the weirder it gets. I was lying in the bath thinkng about M.C. Escher (specifically Ascending and Decending, 'impossible objects', false-perspectve grids and Chinese brush paintings.

Now, after the bath, I'm off to bed.

Cheers,

R.
 
I must be blind ,as I do not see blank space as the subject here. I see girl, bike, barn, as subjects. Must be psychological.
 
Good night, Roger.

Sun just came out, think I'll try the 12.5mm F1.4 Kowa C-Mount lens on the EP2.
 
Actually the picture (Becky, Bike, Barn) demonstrates how we perceive the face of objects. In this one, the girl is looking hard right, the bike looks left-center, and the barn hard left. All that suggests radiance from the empty center sky. Finally, considering the visual weight of objects, the bike and barn together complement the girl to create balance.

(This photo is used in a university art and photography class to discuss one facet of composition.)

Photo by moi, 1973.
 
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