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Thread: Perspective of lenses vs focal length

  1. #1

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    Originally posted by Jed

    Okay, this is a very common misconception which a lot of people have. The reality is that perspective doesn't change with zooming or by changing lenses. In reality a 14mm lens has exactly the same perspective as a 400mm lens. The only thing that changes perspective is your feet, or your subject's feet. In other words, the distance between camera and the subject. That creates the perspective and it's up to the photographer to then pick a lens that will frame the subject correctly.
    Could you elaborate on this a little more?

    I seem to be suffering from the misconception you mention.

    Assuming the subject is, say, 3 feet from me, the perspective using a 14mm lens would definitely be different from that of a 400mm lens, wouldn't it? How would I move the camera relative to the subject to retain the same perspective using the different lenses?

  2. #2

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    Streetshooter :

    Perspective is determined by camera-to-subject distance. Whether you have a normal, wide-angle, or telephot lens, perspective is the same if the camera-to-subject distance remains the same. When you get close to a subject, as you might with a wild-angle lens, nearby objects look unusually LARGE, and distant objects look small and far away. This is because the distance between the near and far subjects is great compared to the distance from the camera to the near subject. The wild-angle lens exaggerates space relationships by expanding the appearent distance between nearby and distant objects. You'll increase the feeling of vastness in scenic pictures by using wild-angle lens and including a nearby foreground object, such as a person, tree, or automobile, for size comparison.

    For the same reason-exaggerated perspective-a close up picture of a person's face made with a wild-angle lens gives the features a DISTORTED APPEARANCE. The nose, because it is close to the camera, look bulbous, while the more distant ears look exceptionally small. IF you use a wild-angle lens to take a picture of an automobile(car, boat) from a front angle, it will look especially LONG and SLEEK. A hand or leg stretched toward a wild-angle lens looks as large as or larger than the head of the person offering the greeting.

  3. #3

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    I think we need to define perspective.... but this belongs in a different thread.

  4. #4
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    Done.

  5. #5

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    like that like no head no tail, u should also move your thread :


    Could you elaborate on this a little more?

    I seem to be suffering from the misconception you mention.

    Assuming the subject is, say, 3 feet from me, the perspective using a 14mm lens would definitely be different from that of a 400mm lens, wouldn't it? How would I move the camera relative to the subject to retain the same perspective using the different lenses?

  6. #6
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    Originally posted by StreetShooter
    I think we need to define perspective.... but this belongs in a different thread.
    From dpreview ( http://www.dpreview.com/learn/Glossa...pective_01.htm )

    Perspective is an effect caused by the picture angle which the focal length of the lens produces, it changes the way an image looks both in the size of objects and depth of view in the image. At wider angles (read smaller focal lengths, eg. 28mm) the background appears to be MUCH further away from any subject in the foreground than your eye would normally see (exaggerated perspective) and narrow angles (reader longer focal lengths, eg. 200mm) the distance between background and foreground objects seems much shorter (compressed perspective).
    Perspective is affected by subject distance, which is defined as:

    http://www.dpreview.com/learn/key=subject_distance
    Subject distance is just the distance from the camera (lens) to the main subject, varying this distance along with the focal length will produce different perspectives.

    Varying the subject distance with the same aperture will produce different a depth of field.

    Regards
    CK

  7. #7
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    Originally posted by ninelives
    like that like no head no tail, u should also move your thread :


    Could you elaborate on this a little more?

    I seem to be suffering from the misconception you mention.

    Assuming the subject is, say, 3 feet from me, the perspective using a 14mm lens would definitely be different from that of a 400mm lens, wouldn't it? How would I move the camera relative to the subject to retain the same perspective using the different lenses?
    done too.

    Regards
    CK

  8. #8
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    Rather than talk about it, a picture is worth a million words. Go here for some understanding on Focal Length, Depth of Field and Perspective, and how they all live together sinfully....

    Luminous Landscape Article

    p.s. after going thru the article again, realised it was more related to DOF, but what the hey....

  9. #9
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    9lives has explained it very well in his reply.

    A 14mm lens from 3 feet and a 400mm lens from 3 feet yields exactly the same perspective (not to be confused with angle of view). Only, to shoot the same subject, you would have to back up A LOT with the 400mm, and it's this backpeddling, not the lens, that results in the visible diffence in perspective.

    Nice to be able to make a correction without getting bitten into... and a credit to you Streetshooter.

  10. #10

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    OK, I get it now.

    With a wide angle lens you need to get closer to the subject to frame the picture reasonably whereas with a telephoto you need to get further away to frame a similar picture. The difference in distance from the subject determines the change in perspective, not the focal length of the lens or the angle of view.

    Which makes my original point still valid - you want a certain perspective, you need a certain lens!

  11. #11
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    Originally posted by StreetShooter
    OK, I get it now.

    With a wide angle lens you need to get closer to the subject to frame the picture reasonably whereas with a telephoto you need to get further away to frame a similar picture. The difference in distance from the subject determines the change in perspective, not the focal length of the lens or the angle of view.

    Which makes my original point still valid - you want a certain perspective, you need a certain lens!
    That's right in that perspective (pun intended). But we are just trying to say, focal length does not affect perspective if subject size is not kept constant.

    Regards
    CK

  12. #12

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    Yes, that's it. The corollary is that if subject size is to remain constant within the frame, perspective changes dramatically with the use of different focal length lenses.

  13. #13
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    Originally posted by StreetShooter
    Yes, that's it. The corollary is that if subject size is to remain constant within the frame, perspective changes dramatically with the use of different focal length lenses.
    Right on.

    On a related note, DoF of a lens does not change if you keep subject size constant, regardless of the len's focal length.

    Regards
    CK

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