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Thread: Observation on focal length and portrait drawing

  1. #1

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    Observation on focal length and portrait drawing

    I share the following in case it may be of interest to other portraitists, expecially those relatively new to the field,. I am by no means new to it but am taking a new turn in my course and am discovering along the way some things I hadn’t previously recognized fully.

    Many have seen examples, in books or on the web, of the effect of focal length on the way the lens “draws,” or renders, the face. A model, head height filling the frame, is photographed repeatedly, starting with a very wide-angle lens and each time with a longer focal length while the photographer backs away to maintain constant head size. The increasing spacial compression widens the face and neck in a straight-on frontal view.
    Although about 6 feet (2 meters) lens to subject is often cited as a minimum distance for proper facial drawing, my curiosity had been aroused by numerous images taken from much closer distances than I for many years would have used, and with shorter lenses, while maintaining an apparently normal view (i.e., no obviously unusual effect.) Over the weekend, I made a series of tests, in three formats (4x5, 645, 35mm) with the lenses I have, making images from as close as about 3.5 feet, then 4, 5, 6, 8, and 10 feet. I chose a few of the negs from each format and enlarged them to keep the head size fairly constant.

    Instead of a fronal view, however, I chose a 3/4 view, which is more typical for my work. Although I did not have a professional model and the tests show more variation of pose “slippage” than I’d like, they show something that in hindsight is ovbious. Rather than thinning the face, the 5’ and closer images make it appear a bit fuller. The cause is the same as that in frontal views of course: parts of the face closer to the camera are enlarged more than those further away, a simple result of perspective. In this case, the cheek and close jaw side bulge slighly. The effect is subtle with the distances I used (no extreme close-ups) but notable.

    These photos also confirmed for me that the close shoulder and arm, though subject to the same optical law, do not appear unusually large, although arms and legs extended toward the camera, if included with a short or normal focal length fron these distances, certainly did. Certain poses with hands would similarly.

    I like the expression (not mine) that there are no recipes, only solutions to problems. Each artist has his or her vision. My observation is just one, small aspect of the infinite facets of portrait photography, affected by angle, lighting, head gesture (turn, tilt, etc.), and so on. Just something I will be aware of now that I have done the experiment myself and feel comfortable moving in closer with a shorter lens than I would have previously.

    (My lenses range from 35mm to 90mm, in 35mm approximate equivalents.)
    Last edited by Ulophot; 9-Sep-2019 at 12:39. Reason: typos
    Philip U.

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  2. #2
    Vaughn's Avatar
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    Re: Observation on focal length and portrait drawing

    Distance to subject will determine perspective (especially the type called foreshortening). The desired perspective is subjective...and I believe we are getting use to increased foreshortening as 'normal' -- most likely due to viewing phone images.

    That was a good exercise -- it is good to know how our lenses see.
    "Landscapes exist in the material world yet soar in the realms of the spirit..." Tsung Ping, 5th Century China

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    Re: Observation on focal length and portrait drawing

    Lookup foreshortening.

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    Re: Observation on focal length and portrait drawing

    Quote Originally Posted by Vaughn View Post
    Distance to subject will determine perspective (especially the type called foreshortening). The desired perspective is subjective...and I believe we are getting use to increased foreshortening as 'normal' -- most likely due to viewing phone images.

    That was a good exercise -- it is good to know how our lenses see.
    Distance to lens has absolutely nothing to do with perspective.
    Perspective is only changed by the angle of the camera to the subject.
    Foreshortening is not perspective. It is an optical effect controlled by focal length and distance and, to some degree, subject pose.

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    Re: Observation on focal length and portrait drawing

    A very good observation. We all see many phone images even if we are not on the big social sites.

    News and TV is affecting our vision.


    Quote Originally Posted by Vaughn View Post
    Distance to subject will determine perspective (especially the type called foreshortening). The desired perspective is subjective...and I believe we are getting use to increased foreshortening as 'normal' -- most likely due to viewing phone images.

    That was a good exercise -- it is good to know how our lenses see.
    sin eater

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    Re: Observation on focal length and portrait drawing

    Quote Originally Posted by Bob Salomon View Post
    Distance to lens has absolutely nothing to do with perspective.
    Perspective is only changed by the angle of the camera to the subject.
    Foreshortening is not perspective. It is an optical effect controlled by focal length and distance and, to some degree, subject pose.
    Distance has everything to do with perspective. The relative sizes of objects in the frame is changed by distance from the camera, with things closer looking larger than things farther away. Keystoning is a different issue.

    And foreshortening is not an "optical effect," it arises from different parts of the body being closer to the camera. The amount of foreshortening would not change with focal length, but changes when the distance to subject is changed to get the same framing.
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    Re: Observation on focal length and portrait drawing

    Quote Originally Posted by Corran View Post
    Distance has everything to do with perspective. The relative sizes of objects in the frame is changed by distance from the camera, with things closer looking larger than things farther away. Keystoning is a different issue.

    And foreshortening is not an "optical effect," it arises from different parts of the body being closer to the camera. The amount of foreshortening would not change with focal length, but changes when the distance to subject is changed to get the same framing.
    Sorry, but foreshortening is not perspective. It is only angle that changes perspective.

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    Re: Observation on focal length and portrait drawing

    I had hoped not to spawn this debate.
    Philip U.

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    Re: Observation on focal length and portrait drawing

    Quote Originally Posted by Bob Salomon View Post
    Sorry, but foreshortening is not perspective. It is only angle that changes perspective.
    ... and the angle of objects near the lens but on the side of the field of view changes greatly with lens-to-subject distance. Hence, using your own definition, foreshortening is perspective of a type.

    Really, common usage of the word "perspective" includes just about all the ways objects are projected through a lens onto whatever surface as well as lensless geometric projections (think cartography).When I explain camera movements to beginners or interested parties, the easiest introduction is to say that "we can use camera movements to control perspective..." I can't imagine a simpler way. Maybe we shouldn't limit the definition of the word so strictly.

    Best,

    Doremus

  10. #10
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    Re: Observation on focal length and portrait drawing

    Quote Originally Posted by Bob Salomon View Post
    Sorry, but foreshortening is not perspective. It is only angle that changes perspective.
    Sorry, but you are incorrect. Perspective is the relationship between objects in the frame as seen on a 2D-plane, and these relationships inherently depend on their relative distances from the camera position. Wide-angle "distortion" is an element of perspective, but not the entirety.

    Quote Originally Posted by Ulophot View Post
    I had hoped not to spawn this debate.
    Apologies, but it seems inherent to your topic.
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