Page 1 of 13 12311 ... LastLast
Results 1 to 10 of 122

Thread: That elusive term: "Perspective"

  1. #1
    Land-Scapegrace Heroique's Avatar
    Join Date
    Nov 2008
    Location
    Seattle, Wash.
    Posts
    2,562

    That elusive term: "Perspective"

    There’s a current “Style & Technique” thread about front & back shifts with several competing opinions about which of these shifts (if not both) changes “perspective.”

    Might this deserve a quick specialized thread?

    BTW, I fall into the camp that says FRONT shift (L or R) will change perspective – not BACK shift. Same with rise/fall: that is, front rise/fall changes perspective – not back rise/fall.

    But is it possible to summarize in a sentence what type of movement DOES change perspective (short of moving your entire tripod/camera)?

    Perhaps I’d say … Whenever your lens axis moves in relation to your subject. (Would this be sufficient? Or perhaps I missed that lecture in LF 101?)

    If this is correct, I can still think of lens movements that do NOT change perspective – namely, front axial tilt, and front axial swing…

    What would your brief explanation be? Can you share moments from the field for illustration?

  2. #2

    Join Date
    May 2004
    Location
    Montara, California
    Posts
    1,803

    Re: That elusive term: "Perspective"

    Front shift changes perspective, not back shift. I think the problem is that people are using the word "perspective" sort of loosely.

    It is easy to demonstrate with a thought experiment: Imagine a pencil tip sticking into the frame, two inches in front of the lens. The pencil tip "touches" the tip of a distant mountain.

    Now move the rear standard all you want. Up, down, sideways. All you are doing is cropping or selecting from an image projected behind the lens. The image is larger than 4x5 but it does not change as you select first one part then the next.

    Now move the front standard. The distant mountain moves not at all (as far as the eye can notice, at least) but the pencil moves rapidly and dramatically. If fact, you can move the pencil (but not the mountain) right out of the frame. Thus, moving the front standard is just like moving the camera for fixed lens cameras. Moving the lens changes perspective (although the change in perspective will likely be unnoticeably small in many images).

    --Darin

  3. #3
    Land-Scapegrace Heroique's Avatar
    Join Date
    Nov 2008
    Location
    Seattle, Wash.
    Posts
    2,562

    Re: That elusive term: "Perspective"

    Quote Originally Posted by Darin Boville View Post
    It is easy to demonstrate with a thought experiment: Imagine a pencil tip sticking into the frame, two inches in front of the lens. The pencil tip "touches" the tip of a distant mountain...
    Very nice – brief and quite elegant!

    Quote Originally Posted by Darin Boville View Post
    Moving the lens changes perspective (although the change in perspective will likely be unnoticeably small in many images).
    But is this part still true?

    When one "moves the lens" w/ front-axial tilt (or front-axial swing), does the perspective necessarily change?

  4. #4

    Join Date
    Mar 2008
    Location
    Beaverton, OR
    Posts
    650

    Re: That elusive term: "Perspective"

    Aren't you moving the film in relation to the image circle?

    If true you are changing the line of sight for the film. The film is still seeing essentially the same number of degrees, say 45, within the circle, it's just not seeing the same 45 degrees,it will be offset one way or the other.

  5. #5

    Join Date
    Sep 1998
    Location
    Oregon and Austria
    Posts
    1,870

    Re: That elusive term: "Perspective"

    Here's the definition of the word "perspective" from the Cambridge dictionary as it applies to art:

    "perspective: the way that objects appear smaller when they are further away and the way parallel lines appear to meet each other at a point in the distance."

    Here is another from WordWeb:

    "The appearance of things relative to one-another as determined by their distance from the viewer."

    As you can see, there are two components to these definitions. First, the appearance of things as related to viewpoint (i.e., moving the camera or the lens position), and, second, the rendering of where parallel lines appear to meet in the distance.

    If we grant both aspects of the definitions above to be valid, then we end up with a two part answer when applied to view cameras. First, moving the camera, or on a smaller scale, moving the lens to a different position effectively moves the "eye" of the photographer to a different point in space thus changing the viewpoint and the perspective in the sense of "the appearance of things relative to one another."

    However, if we swing or tilt the back of the camera, even though it (and the lens) remains in the same position, we change the way parallel lines in the subject are rendered, thus changing perspective in that sense.

    In other words, the term "perspective" is not univocal and, when using it in situations where it is ambiguous, we should qualify what we mean by it in order to clarify.

    From the above we can conclude the following:

    1. Moving the camera or using front shift or rise/fall changes perspective by changing the viewpoint and the relationship of objects in the scene. Using front swing and tilt does not do this except inasmuch as it moves the lens from its original position. (Axis movements move the lens much less from the original position than base tilts). Therefore, we can say that "theoretically," front swings and tilts do not change perspective.

    2. Back shift and rise/fall do not change the position of the viewpoint, just crops a different part of the projected image and, therefore, does not change perspective since the relation of objects in the scene remains the same. However, back swings and tilts change the way parallel lines are rendered in the image and, therefore, change perspective in this way, without changing the relationship of objects in the scene.

    Sorry, this was a lot more than a simple sentence, but sometimes you just have to be thorough...

    Best,

    Doremus Scudder

  6. #6
    Land-Scapegrace Heroique's Avatar
    Join Date
    Nov 2008
    Location
    Seattle, Wash.
    Posts
    2,562

    Re: That elusive term: "Perspective"

    Quote Originally Posted by Doremus Scudder View Post
    However, if we swing or tilt the back of the camera, even though it (and the lens) remains in the same position, we change the way parallel lines in the subject are rendered, thus changing perspective in that sense...
    This is quite revealing!

    Back swings & back tilts change perspective afterall, if one has been careful to define the term with precision.

    All your careful attention to "Perspective" reminds me of the anecdote about the Italian Renaissance artist, Uccello, who would spend all night perfecting its use in painting...

    When called to bed by his wife, he would cry out:

    "O, che dolce cosa e questa prospettiva!" ("How delightful perspective is!")

  7. #7

    Join Date
    May 2004
    Location
    Montara, California
    Posts
    1,803

    Re: That elusive term: "Perspective"

    >>Here's the definition of the word "perspective" from the Cambridge dictionary as it applies to art:<<

    Of course, the the definitions in your dictionary are not specialized ones--and as photographers--large format photographers no less--we are by talking about a specialized field with specialized words.

    For example, in my dictionary the definitions for fall, rise, shift, tilt, etc don't quite capture what I mean and what you, as a specialist, immediately understand me to be talking about. It is the same with perspective.

    The idea of perspective is usually introduced to students (students of a specialized field) in a sort of reverse way--to counter misconceptions they have that changing lenses changes perspective. They are shown that the telephoto shot is just a cropped shot of the wide angle one--the relationships between the objects in the scene remain unchanged.

    Thus the definition of perspective sneaks in--it is the relationship between objects from a single location, from a single point. Changing lenses is like cropping the scene. Moving the rear standard is like cropping the crop of the scene. Moving the front standard crops, too, but it also moves the position (and, by the specialist definition, the perspective).

    So, "perspective," as used by photographers, is a specialized term with a slightly (and more precise) meaning than the general term found in a regular dictionary.

    For fun:

    Position = choice of perspective
    Lens selection = a crop of the view from that perspective
    Rear standard movement = a crop of the crop of the view from that perspective

    --Darin

  8. #8

    Join Date
    Aug 2007
    Location
    Indianapolis, Ind.
    Posts
    587

    Re: That elusive term: "Perspective"

    I like Darin's approach. I considered proposing that perspective is completely determined by the position of the lens (the front nodal point in particular) and depends on nothing else.

    Would anyone follow the implications of that formulation to the point of concluding that rear swings and tilts also do not affect perspective. They just introduce keystone distortion?

  9. #9
    Ed Rucker
    Join Date
    Dec 2008
    Location
    Longview, Texas
    Posts
    97

    Re: That elusive term: "Perspective"

    well, IMHO you can call it keystone distortion if you like. the end result is that it changes the perspective of an image the same as if an artist were to change the vanishing point in a drawing. using rear swing/tilt in very small amounts will undoubtedly have a substantial impact on your composition. This change, especially in architectural subjects, can only be described by the end viewer as a change in perspective (vanishing point).

    moving your camera a foot one way or the other during set up will likely change your perspective (relative positioning of subjects) a noticeable amount. moving your camera an inch one way or another during setup will almost certainly not change your perspective a noticeable amount. based upon this, it is very unlikely (to me anyway) that using front rise/fall/shift is going to make any noticeable impact on the resulting image (unless of course you are shooting macro).
    Ed

  10. #10

    Join Date
    Mar 2008
    Location
    Beaverton, OR
    Posts
    650

    Re: That elusive term: "Perspective"

    Quote Originally Posted by Doremus Scudder View Post
    2. Back shift and rise/fall do not change the position of the viewpoint, just crops a different part of the projected image and, therefore, does not change perspective since the relation of objects in the scene remains the same. However, back swings and tilts change the way parallel lines are rendered in the image and, therefore, change perspective in this way, without changing the relationship of objects in the scene.
    I agree that the lens's veiwpoint and the projection created by the lens does not change with backshift.

    What I'm suggesting is that from the perspective of the film/ground glass, any shift (front or rear), imparts a change in the composition and therefore a change in the "viewed" perspective.

Similar Threads

  1. printer long term storage
    By vicgin in forum Digital Hardware
    Replies: 10
    Last Post: 10-Mar-2009, 09:30
  2. A Blog and discussion about that *$%%# elusive Swirly Bokeh!
    By Jim Galli in forum Style & Technique
    Replies: 55
    Last Post: 12-Mar-2008, 16:32
  3. Long Term Frozen Storage
    By John Cook in forum Darkroom: Film, Processing & Printing
    Replies: 14
    Last Post: 6-Sep-2004, 02:02
  4. flash sync on LF lens without sync term (compound shutter)
    By Mike Netecke in forum Lenses & Lens Accessories
    Replies: 9
    Last Post: 22-Jun-2004, 09:21
  5. More Long Term Cataloguing of these Archives
    By Andre Noble in forum Announcements
    Replies: 2
    Last Post: 10-Nov-2001, 19:07

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •