perspective w/ 35mm lenses?

Discussion in 'Digital Photography' started by PrincePete01, Jul 16, 2004.

  1. PrincePete01

    Nostrobino Guest

    Sorry, I have no idea who Preddy is.

    That may be someone I plonked. In any case, I don't see that being a lens
    designer makes anyone particularly qualified to say what perspective is or
    is not. It is really more a term of art than of optical technology: there
    were very elaborate and complex perspective drawings long before there were
    cameras--at least as long ago as the 15th century, if I'm not mistaken.

    Very well, I accept the difference then. However, I must point out again
    (and I'm sorry for being repetitious, but you understand that it's
    unavoidable in this case with this means of communication) that my
    vocabulary at least in this instance comports EXACTLY with that of the Focal
    Encyclopedia that you quoted from. I am using the term "perspective" EXACTLY
    as your encyclopedia uses it--to mean the perspective of the picture as a
    whole, not some small part of the picture. That has really been the crux of
    the argument all along, as I've mentioned before.

    That the encyclopedia makes a statement about perspective which is clearly
    inconsistent with its own use of the word is regretable, but you certainly
    cannot say my usage of the word disagrees with its own.
     
    Nostrobino, Aug 6, 2004
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  2. No you are not, and if you think you are you are clearly
    misunderstanding it.
    No it doesn't. How any native English speaker could reach this
    conclusion is a bizarre mystery. I suspect you may, after all, be
    trolling.

    What it says - and I paraphrase - is that people err in thinking that
    the "wide angle perspective" comes from the use of a wide angle lens,
    and that it really comes from the choice of taking position normally
    used with such a lens. This is of course completely the opposite of your
    "interpretation".

    Read it again.
     
    David Littlewood, Aug 6, 2004
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  3. A troll who insists on posting misconceived stuff even though no-one
    else agrees with him or believes a word he says.
    My opinion of Brian's expertise is based on my reading his views over a
    prolonged period. In contrast, I don't recall ever seeing any posting
    from you that is not full of misinterpretations.
    Good grief, you don't give up, do you. This is a totally perverse
    reading of an authoritative quote which flatly refutes most of what you
    have been saying.

    I think I should have taken my own advice.
     
    David Littlewood, Aug 6, 2004
  4. PrincePete01

    Nostrobino Guest

    Why should it be different?

    And the Focal Encyclopedia of Photography is NOT "talking about
    photographic/optical perspective" when it speaks of "abnormal linear
    perspective" (the encyclopedia's term) such as the "strong perspective"
    associated with wide-angle lenses and "weak perspective" associated with
    telephotos?

    How different?

    Of course we almost always look at wide-angle photos "from too far away,"
    i.e. at some distance from which our angle of view is smaller than the
    camera's was when it took the picture; and contrariwise with long-lens
    photos. I have even seen in print, a number of times, the advice that even a
    fairly small print from a 135mm telephoto shot should be viewed from a
    distance of several feet in order to make its perspective "correct." That's
    nonsense, of course. Not the part about making its perspective correct,
    obviously that's true, but who on earth would actually view the print from
    such a distance? It would defeat the whole purpose of using a long lens in
    the first place.

    If you are insisting that "photographic" perspective has some different
    meaning from "artistic" perspective, then it is you who are at odds with the
    way the word "perspective" is used in the Focal Encyclopedia of Photography,
    not I.

    Of course. There has never been any question about that. All you are saying
    is that enlargement does not change the perspective of a small part of the
    image. No one ever said it would. That is, after all, all the telephoto lens
    itself is doing.

    However, when you do that with an existing wide-angle image you are simply
    throwing out most of the picture as if it were irrelevant to perspective.
    That's not valid. Every element of a picture that has a bearing on
    perspective contributes to the perspective of the picture. It is the picture
    AS A WHOLE that has perspective.

    Only if you are applying some special meaning to "photographic perspective"
    that those words themselves do not carry, and that is not supported by the
    Focal Encyclopedia of Photography either. That should cause you to
    reconsider what you are insisting.

    Again: That's not what the photography encyclopedia says. (It does, however,
    make a statement about perspective which is inconsistent with, and
    contradicted by, its own use of the term.)

    It is, though. The Focal Encyclopedia speaks of the "strong perspective"
    associated with wide-angle lenses and the "weak perspective" associated with
    telephotos, calling both forms of "abnormal linear perspective."

    I am using the same definition as the Focal Encyclopedia of Photography.
    That's not a sufficiently authoritative source for definitions? (If you say
    their REASONING is somewhat screwy I would have to agree. But their
    DEFINITION seems fine to me.)

    As long as the encyclopedia's meaning of the word agrees with my own, I
    suppose I can live with the occasional improper usage in newsgroups. But it
    would sure be better if everyone used the term correctly.
     
    Nostrobino, Aug 6, 2004
  5. PrincePete01

    Nostrobino Guest

    I have not shifted my ground.

    Actually, it speaks of "camera position" and does not mention "viewing the
    print from a position inconsistent [etc., etc.]" at all. But yes, I agree
    with you that that's what causes the difference in perspective.

    So what? Everyone normally views such prints from such "inconsistent" or
    "improper" distances. In the case of long lenses, the chief if not only
    reason for using such lenses in the first place is to make it POSSIBLE to
    view the subject from an apparently closer distance and/or at a more
    pleasing perspective (as in portraiture). No one in his right mind takes a
    long-lens shot and then mounts a small print of it across the room just so
    he can see it in the "proper" perspective.

    Actually, I've been wondering how you DO use the word "perspective" if you
    only use it to mean what you've been claiming. You seem to have redefined
    the word out of all possible usefulness.

    I thought you were. Somebody here is.

    I did not omit it; I quoted all that part earlier in the same post.

    It does indeed, and it makes no sense whatever. The same piece that says "it
    is the camera position and not the focal length or type of lens that
    produces the abnormal linear perspective" just finished saying that "strong
    perspective is often associated with wide angle lenses and weak perspective
    is similarly associated with telephoto lenses." Since there is no way on
    earth that camera position can make a long lens produce that "strong
    perspective" associated with a wide-angle lens, etc., this is nonsensical on
    its face.

    Change the camera position all you like, the wide-angle lens will still
    produce what that encyclopedia calls "strong perspective," or what I have
    been calling wide-angle perspective--and the telephoto lens never will. I am
    fairly sure you know this as well as I do.

    I am fully agreeing with your encyclopedia's usage of "perspective," meaning
    a quality that involves the entire picture. You're not really disagreeing
    with THAT, are you? Your "overwhelming majority of those here" have not been
    agreeing with that usage, or there would not have been so many claims that
    enlarging the center of a wide-angle shot (and discarding everything else)
    "proves" that it has the same perspective as a long-lens shot. So on that
    count at least, it's your encyclopedia and me against "the overwhelming
    majority of those here."

    No, from my perspective the angles were all wrong.
     
    Nostrobino, Aug 6, 2004
  6. You have. Either your memory or your veracity is flawed.
    It clearly means "is associated in the mind of the ill-informed, who are
    incorrect." If you can't see that - and you clearly can't - then there
    is no point in continuing.
    ....By changing the camera position.
    It didn't say that. In fact it goes out of its way to say something
    different.
    Utter, utter bollocks. The dictionary piece says the exact opposite of
    what you say, as has almost every other contributor here. Your views, as
    expressed here, are simply perverse.

    I'm done wasting time on this, you just won't listen.
     
    David Littlewood, Aug 6, 2004
  7. Utter bollocks - it flatly contradicts your view.
     
    David Littlewood, Aug 6, 2004
  8. That's not what was said. "Associated with" does not equal "results
    from". Correlation does not prove causality.

    In the early part of this century, a greater percentage of people who
    moved to the desert southwest died of Tuberculosis than those who
    remained on the east coast. At the time, one could have written:

    "Since a greater percentage of people moving to the desert southwest
    die from Tuberculosis and a lesser percentage of people remaining on
    the east coast die from Tuberculosis, death from Tuberculosis is often
    associated with moving to the desert southwest and surviving the
    disease is similarly associated with remaining on the east coast."

    This is logically equivalent to the first portion of the text David
    quoted.

    Does this mean moving to the desert southwest caused Tuberculosis in
    people? Of course not. In fact, moving to the drier climate of the
    desert southwest was better for people suffering from Tuberculosis.
    Thus more people who were suffering from Tuberculosis would move
    there, artificially inflating the per capita death rate from the
    disease.

    In terms of Tuberculosis deaths, the rest of the text David quoted
    could be written as follows:

    "... is similarly associated with remaining on the east coast, but it
    is the fact that a greater percentage of Tuberculosis sufferers move
    to the drier, healthier climate of the desert southwest and not the
    move itself that produces the difference in death rates."

    Even better... a greater per-capita percentage of people who die do
    so while they are in hospitals. Does this mean that going to a
    hospital is more likely to kill you than not going?

    I knew those darn hostpitals were death traps...

    The fact that strong perspective is often associated with wide angle
    lenses does not necessarily mean that the wide angle lens is the cause
    of the strong perspective. Similarly, the fact that weak perspective
    is often associated with telephoto lenses does not necessarily mean
    that the telephoto lens is the cause of the weak perspective. Rather,
    it is the position of the camera and not the type/focal length/etc. of
    the lens that produces the perspective.
    Is it enlightened because you interpreted it as agreeing with your
    position? I really do ask this in all seriousness and not to poke
    at you, as it's not uncommon for one to see views similar to one's
    own as "enlightened".

    If enlightened for some other reason, then why wouldn't the remainder
    of the same sentence be equally as enlightened?
    You took one complete sentence, split it into pieces, and then
    analyzed each piece independently; of course it's going to appear
    contradictory to you. You missed the "but" portion of the sentence
    when splitting it up. The author clearly intended to show a common
    fallacy in one's associating perspective with focal length, and
    finished his sentence by stating that said association was incorrect
    and the effect on perspective was in fact caused by something entirely
    different from focal length.

    Sorry to the kids reading... but I'm an evil person... ;)

    "Santa Claus is often associated with the arrival of presents on
    Christmas day, but it is the children's parents who actually place
    those presents under the tree."

    By the same reasoning you used far above, Santa Claus exists and the
    second half of the sentence is "clearly contradictory".

    BJJB
     
    BillyJoeJimBob, Aug 6, 2004
  9. I'm beginning to think that your definition of perspective comes from
    the art world and is not necessarily equivalent and interchangeable
    with the photographic definition of perspective.

    I'm not going to try and define the photographic definition of
    perspective, nor am I going to try and point out the differences
    (if any) between the art and photographic definitions of the word.
    However, based on the strong stances of you and others on this
    subject there surely is a difference--perhaps a subtle one--in
    terminology.
    The only quote I remember seeing from the Focal Encyclopedia is the
    one David made regarding the incorrect association of focal length
    with perspective. At no point in that quote did I see mention of
    perspective of the picture as a whole, nor did I see mention of
    perspective of some spall part of the picture.

    Did I somehow miss a second quote somewhere in this very long
    discussion thread?

    BJJB
     
    BillyJoeJimBob, Aug 6, 2004
  10. PrincePete01

    Nostrobino Guest

    Neither is the case. I have repeatedly made it clear that focal length
    figures were used presuming the same (35mm) format or the digital camera
    equivalent. Did I do so every single time? Probably not, but early enough
    and often enough that anyone with something approaching average intelligence
    would have been able to understand that. On more than one occasion I
    specifically said that by focal length I was actually referring to angle of
    view.

    Now, whose memory or veracity is flawed?

    No one reading that as Standard English would make that interpretation.
    Focal Encyclopedia has gotten itself confused, as it has on other occasions.

    The SIGNIFICANT thing is that they clearly use the terms "abnormal linear
    perspective," "strong perspective" and "weak perspective" to mean the
    perspective as a coherent quality of the entire picture, not some itsy-bitsy
    teensy-weensy part taken out of the middle.


    You're twisting yourself into some sort of linguistic pretzel to avoid
    facing the facts. The piece clearly recognizes that wide-angle lenses "are
    associated with" a certain type of perspective, and telephotos with the
    opposite type, and that people generally recognize this. If not for that
    there would be no such associations for the encyclopedia to take notice of.
    And those are, of course, perfectly proper ordinary understandings of the
    word "perspective."

    Now Dave Martindale here is agreeing that there's "artistic perspective"
    which is inseparable from field of view, and "photographic perspective"
    which is different. This is news to me, and I imagine to most people who
    have always regarded geometric perspective as something independent of the
    medium that uses it. As far as I'm concerned, perspective is perspective.
    Artists used it at least 300 years before photographers ever did.

    I'm frankly amazed that you can read that and so thoroughly misunderstand
    what you're reading. It's clear enough to me. The Focal Encyclopedia seems
    to have done here just what it's done with "prime lens"--first defined the
    term correctly, then (in a later edition, and without changing the original
    definition) misused it to conform with more recently popular misusage. So
    this is no surprise to me. Perhaps the pliant editors at some point
    somewhere read that nonsense about camera position alone determining
    perspective, were gulled by it as easily as you were, and modified their
    original comments on perspective to try to incorporate the new
    fallacy--resulting in the self-contradictory mishmash you've quoted.

    Go in peace, brother. Think you'll ever find an actual use for "perspective"
    as you (and the "overwhelming majority of those here" of course) have
    redefined it? It seems unlikely to me that you ever will; you've bludgeoned
    it into about as useless a word as can be imagined.
     
    Nostrobino, Aug 6, 2004
  11. PrincePete01

    Nostrobino Guest

    It uses the word "perspective" to mean exactly what I have been saying it
    means: the perspective of the picture as a whole.
     
    Nostrobino, Aug 7, 2004
  12. PrincePete01

    Nostrobino Guest

    Yes, I assure you I am grateful. It so completely supports my usage that
    frankly I wondered why you were posting it.

    You might like to try explaining what you think the terms "strong
    perspective," "weak perspective" and "abnormal linear perspective" mean,
    then. Just say EXACTLY what you think "strong perspective" (wide-angle
    perspective) means, for example. Not just what you think produces
    it--describe it.

    Be serious. Trolls don't do what I do and I don't do what trolls do.

    Or are you going to redefine that word too?

    It doesn't say, hint, suggest or imply that "people err in thinking"
    anything. There is absolutely nothing in the quoted piece that says anything
    remotely like that. You're making that up out of thin air.

    You agree that it does acknowledge there is such a perspective, then.

    I've read it several times. It says exactly what I said it says. It
    acknowledges that certain types of "abnormal linear perspective" are
    "associated with" certain types of lenses ("strong" and "weak" perspective
    for wide-angle and telephoto lenses respectively). This is correct. Then it
    says these types of perspective are really produced by camera position and
    not focal length. This is demonstrably incorrect. No camera position will
    ever produce "strong perspective" (wide-angle perspective) with a long lens.
    I think you know this as well as I do. Don't you?
     
    Nostrobino, Aug 7, 2004
  13. No, it's not. But they're using two slightly different meanings of
    perspective in the same paragraph.

    The wide angle photo shows much stronger perspective-related effects
    than the telephoto shot *when both are viewed with the same visual
    angle*.

    On the other hand, if both are viewed with the visual angle of the
    corresponding taking lens, there is no unnatural perspective at all.

    It's perfectly reasonable to say that the "wide angle perspective" is
    really the result of viewing the print from a greater distance,
    occupying a smaller visual angle, than is correct. Similarly, the
    "telephoto perspective" can be said to be the result of looking at the
    print from too small a distance, with too large a visual angle.
    This is just as true as saying the change in apparent perspective is due
    to the change in camera lens.

    So, if you assume a constant print size and viewing distance, you can
    change perspective by changing lens. If you also keep about the same
    amount of the in-focus object within the frame, you will have to change
    the camera-subject distance in proportion to the focal length. And when
    you do that, the change in apparent perspective is due to the camera
    position change - not the focal length change.

    On the other hand, depending on your assumptions about linear and
    angular field of view, and print size and viewing distance, all of the
    variables are tied together anyway. So it's a little bit untrue to say
    which one "causes" and which one is "caused by". The quote above is
    trying to tell you that just changing lenses *alone* will not change
    perspective, while moving the camera *alone* does change perspective.
    Both of these, however, also change the space that is included in the
    image.
    Yes you can. If you assume a particular print size and viewing
    distance, that determines the focal length of lens *and camera position*
    that will give you a completely undistorted view.
    No, it does so as long as your viewing distance is such that the print
    occupies a smaller visual angle than the original scene. That's the
    only thing that's special about a wide-angle lens.
    But whether it is absolutely correct, shows "telephoto distortion", or
    even "wideangle distortion" depends on viewing distance and print size.

    Dave
     
    Dave Martindale, Aug 7, 2004
  14. Because there is a need to talk about what it talks about, and it's not
    the same thing as "artistic perspective".
    No. It's talking about the change in apparent perspective when the lens
    FL changes without a corresponding change in print viewing distance.
    On the other hand, if you adjust viewing distance along with FL, then
    there is no change in perspective at all - just field of view.

    Both of these statements are true; why do you insist that only one can
    be?
    What is your difference metric? The point is that they mean things that
    sometimes conflict.
    If the purpose was to create an artificial perspective. But people
    often change lenses primarily for field of view from a fixed location.
    I was talking about how it was used in the discussion in this newsgroup.
    And as you noted, that paragraph in the FEoP has two somewhat different
    meanings in the same paragraph. You are the one insisting that there is
    only One True Meaning of Perspective.
    Using one definition of perspective.
    No. I have no problem with the FEoP definition. It makes perfect sense
    to me. I know what it's telling me about optics. And I just don't care
    if it uses "perspective" in different ways in the same paragraph. It's
    not a mathematical proof; it's an informal description of a process.
    It's contradictory only because of the way you read the paragraph, and
    your insistence that there's just one meaning of the word.
    Which is true given their (unstated) assumptions of constant viewing
    angle for the print.
    It's an informal description, not a precise definition. There's nothing
    wrong with their reasoning, since what they state is true, but they do
    not provide a listing of their assumptions nor a definition of the terms
    involved.
    But it has two somewhat different meanings within the same paragraph.
    You can't simultaneously say that the encyclopedia agrees with you, and
    also say that the second half of the definition is wrong. Maybe you
    should say that it half-supports your position.

    Dave
     
    Dave Martindale, Aug 7, 2004
  15. PrincePete01

    mcgyverjones Guest

    The definition of strong perspective and weak perspective is
    usually illustrated with diagrams or photographs showing, for example, a
    house and a mountain.
    The scene is show three times to demonstrate weak, normal and strong
    perspective. In each case the lens is changed (tele, prime and wide) and
    the camera position adjusted closer to keep the house the same basic
    size in the frame. The result is three pictures of a house and a mountain in
    which the house remains about the same size and the mountain decreases in
    size relative to it. The house itself displays a dramatic change in
    appearance due to the change in perspective -- due solely to the change in
    camera position. The wide angle lens simply allows the scene to be
    encompassed in the frame.
    Perspective refers to the relationship of objects to one another. This is
    not really disputable, despite the efforts shown here.
    Unfortunately, ordinary understandings of all sorts of things are often
    wrong.
    Do you belong to the Flat Earth society by any chance??
    Actually it is a useful word and concept, just commonly misunderstood.

    MJ
     
    mcgyverjones, Aug 7, 2004
  16. PrincePete01

    mcgyverjones Guest

    I'll repeat part of what I posted elsewhere since it may have become lost in
    the shuffle:

    The definition of strong perspective and weak perspective is
    usually illustrated with diagrams or photographs showing, for example, a
    house and a mountain.
    The scene is show three times to demonstrate weak, normal and strong
    perspective. In each case the lens is changed (tele, prime and wide) and
    the camera position adjusted closer to keep the house the same basic
    size in the frame. The result is three pictures of a house and a mountain in
    which the house remains about the same size and the mountain decreases in
    size relative to it. The house itself displays a dramatic change in
    appearance due to the change in perspective -- due solely to the change in
    camera position. The wide angle lens simply allows the scene to be
    encompassed in the frame.
    Perspective refers to the relationship of objects to one another. This is
    not really disputable, despite the efforts shown here.
    In order to produce a subject of the same size, you need to shoot closer to
    the subject. This is why faces look so strange in a wide angle portrait. Is
    a pointy face with a sloping forhead and massive nose what you mean by "wide
    angle perspective".
    The same shot with a tele will produce the same perspective, you simply
    won't see much more than the tip of the nose.
    We all know what you mean by "wide angle perspective" and we remember
    thinking the same thing at one time (at least I do). But perspective is
    pretty clearly defined and common misconceptions will not change the facts.
     
    mcgyverjones, Aug 7, 2004
  17. PrincePete01

    Nostrobino Guest

    On reading it YET AGAIN, I agree with you on that point. You are right and I
    was wrong: it does indeed imply that people err in attributing wide-angle
    perspective to wide-angle lenses, etc.

    Of course the article says that camera position being the only factor in
    establishing perspective, and I have agreed from the beginning that it says
    that. In this the article is obviously wrong, since as I've pointed out
    several times already it is not possible to get wide-angle perspective with
    a long lens REGARDLESS of camera position. One could certainly say that IF a
    telephoto lens had the same angle of view as a wide-angle lens from the same
    position, then its perspective WOULD be the same, but what kind of sense
    would that make? If it had the same angle of view then it would be a
    wide-angle lens, not a telephoto.

    It says also that wide-angle lenses are generally used at close distances
    and telephoto lenses at great distances, and this also is not necessarily
    the case. Wide-angle lenses are commonly used to shoot landscapes, or vistas
    where everything is at a great distance. Telephoto lenses are commonly used
    (sometimes even quite strong ones) to shoot portraits at close distance. And
    I regularly use moderately long focal lengths for table-top photography
    (chiefly for items I'm selling on eBay). In all such cases long lenses still
    produce long-lens perspective.

    Now it is true that if all subjects were at a great distance there would be
    no wide-angle perspective (regardless of the field of view), since
    everything would be too far away to show perspective. That's true of long
    lenses too, of course.

    The most significant thing about the article from my <ahem> perspective, and
    probably the reason I missed the implication that you correctly pointed out
    I missed, is its implicit acceptance of the fact that perspective is a
    quality of the picture IN ITS ENTIRETY, as I have said about eleventy-seven
    times here. Again, this is the crux of the argument. Once you've accepted
    that (as your encyclopedia does), then you have to accept that focal length
    (= angle of view) is indeed a determinant of perspective just as camera
    position is.
     
    Nostrobino, Aug 7, 2004
  18. PrincePete01

    Nostrobino Guest

    You mean tele, NORMAL and wide, eh? (Please God, not yet ANOTHER misuse of
    "prime"! It's bad enough already.)


    So far, so good.

    But in "simply allowing" that it has radically changed the perspective of
    the picture AS A WHOLE. If with the camera still at the wide-angle position
    you mounted a tele lens, does the narrower-angle image still have the same
    perspective? No, it does not, and the reason it does not is that most of the
    picture elements that previously contributed to perspective are now missing.
    The PART THAT REMAINS has the same perspective that it did before, yes. That
    has never been in dispute.

    Absolutely! As a minor quibble I would make that "visible or apparent
    relationships," but I think you will agree to that. Primarily this is a
    relationship of angles, sizes and shapes, even if the angles are not always
    apparent.

    I don't know what efforts you mean, but you are certainly correct that it is
    not really disputable.

    That would be one example, yes.

    And you've lost most of the original perspective.

    As you said yourself, and I agreed emphatically: "Perspective refers to the
    relationship of objects to one another." Those are your own words. Again, I
    suggested a change to "visible or apparent relationships," but I think that
    is understood anyway since it's only the perspective in some visible image
    that we're considering.

    Now when you start throwing away objects, specifically objects around the
    edges that contribute importantly to the perspective of the picture as a
    whole, you start to change the perspective OF THE PICTURE. You do not change
    the perspective of the part(s) you haven't thrown away yet, of course. Take
    a long-lens photo, shrink it, surround it with white space, and it still has
    the same perspective it had before. We are thoroughly agreed on that, so
    there is no need to go over that again and again. But if after shrinking it
    you then start adding objects to fill in the surrounding white space, you
    are developing an entirely new perspective, i.e. new objects with new
    visible spatial relationships. This is essentially what a wide-angle lens
    does.

    Then you were all correct in recognizing what was before your own eyes. What
    changed that?

    facts.

    There is no "misconception" in seeing perspective as it actually exists.
    Again (YET again), the perspective of any picture is a quality of that
    picture as a whole--it is not valid to take some little part of it and say
    "that's the perspective." This is the crux of the argument.
     
    Nostrobino, Aug 7, 2004
  19. PrincePete01

    Nostrobino Guest

    Sure, but "apparent perspective" IS perspective. The term only refers to the
    visible or apparent relationships between objects in a three-dimensional
    world. Perspective is not any quality intrinsic to the objects themselves,
    or their physical relationship to one another EXCEPT as perceived from a
    certain point of view, over a certain angle of view. Those last six words
    are the only ones on which we disagree, I think.

    What we have here, as I said very early in this thread (almost my first
    post, I think), is really more an argument about semantics than anything
    else. I am saying that "perspective," as most people who understand the term
    use it, means the angles and relationships, etc., as they are seen under
    ordinary circumstances. For example, one may see a full-page extreme
    wide-angle photo in a book or magazine, and a long-lens photo taking up the
    facing page. No one ordinarily puts his nose down on the page so he can
    squint over at the corners of the wide-angle photo to see them "properly";
    neither does he put the magazine at the other end of the room so that he can
    see the long-lens photo at the "proper" viewing distance. In both cases he
    sees the perspective he sees, with whatever distortions are created by
    "errors" in viewing distance. I put "errors" in quotes because I don't
    really regard these as errors in any practical sense, though obviously they
    do create differences in perspective.

    I really don't think we have any disagreement whatever about the principles
    involved here (unlike your discussions with Spherical Projections Jeremy).
    It is only the appropriate use of the term "perspective" that we differ on.
    Do you agree with this?

    Often, yes, but not invariably. There's a photographer who prefers very long
    lenses (e.g., 300mm on a 35) for shooting half-length pictures of beautiful
    girls. He doesn't NEED a long focal length; the girls are models and will be
    wherever he places them, but he likes the strong look that the spatial
    compression of a really long lens gives him. Similarly, ultrawide lenses are
    liked by some photographers expressly FOR the pronounced wide-angle
    perspective. This ability to CHOOSE perspective (for the sake of perspective
    itself) by selection of focal length is a useful thing for the photographer
    to have, if he's interested in doing that. Don't you agree?

    Not necessarily, but I am saying the common usage is a perfectly valid and
    proper one. It is the people who "correct" others who speak of wide-angle
    perspective, for example, who are being overly restrictive about usage, and
    even artificially so.

    Yes, agreed. That is the real-world case (or close enough to it) in the vast
    majority of cases, I think.

    Okay, it half-supports my position and is mistaken in the other half. :)

    But seriously, I don't think you and I really have any disagreement about
    any of the geometric or optical principles involved here. Our only
    disagreement is over which side is being overly restrictive in defining the
    term. If someone says that camera position establishes perspective, I don't
    attempt to correct them because what they is true. It is equally (and
    demonstrably) true that changing focal length changes perspective; a
    wide-angle lens produces a perspective which a telephoto cannot duplicate.
    The DISTORTION of such an image, if any, depends on print size and viewing
    distance, as you have properly pointed out. Its PERSPECTIVE however is not
    changed by enlargement or reduction, or viewing distance either, any more
    than in the case of cropping and enlarging the center of a wide-angle image
    changes its perspective, as in the several examples much earlier in this
    thread and elsewhere.
     
    Nostrobino, Aug 7, 2004
  20. PrincePete01

    Nostrobino Guest

    Just to make sure I am not misunderstood, of course I meant that "cropping
    and enlarging the center of a wide-angle image" does not change the
    perspective OF THAT PART.
     
    Nostrobino, Aug 7, 2004
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