I thought I'd share a little experiment in perspective I conducted some years back. It is not meant to be anything but an observation, because portraiture is very complex, involving far more factors than merely perspective and foreshortening. The artist may use a host of means to accomplish his or her desired effect, and perspective may play a larger or smaller role therein. Examples now abound on the web, showing virtually identical portraits of a subject made at a number of distances, to demonstrate perspective effects. However, my little contribution may be useful for some newcomers to the field.
Since I tend to photograph on location and include more than just the head and shoulders, I was interested in more than just the facial appearance. The possibility of a full-length seated shot in a relaxed pose was a consideration, and I wondered about avoiding a big foot on a crossed leg coming at the camera in a frontal view, though I wouldn’t necessarily choose that orientation. Turning the subject or moving the camera would diminish that problem, but I thought I'd measure the effect of it.
The test I set up was simple. I sat in a chair with one leg crossed and roughly measured the following distances, back to front, along an imaginary axis parallel to the floor: from the middle of my ear to the tip of my nose; from my nose to a comfortably extended hand, as on a chair arm or table; from my nose to the shoe-tip on my crossed leg (farthest point from my body). These distances were about 5.5, 15, and 30 inches.
I made four identically sized, self-standing cards. I then placed the cards along the edge of a long table (see Picture1), those distances apart, marking the four body points described. Then, measuring from the nose card, I marked off 2-, 3-, 6-, and 9-foot distances and photographed the cards, from the level of their centers, from each distance with a (borrowed) digital SLR.
Loading the files in my computer, I measured the relative sizes of the cards in the several images by using Photoshop’s ruler tool on the height, then derived the ratio of heights of the nose to the ear card, the hand to the nose card, and the toe to the nose card, at each photographed distance. Measurements were all approximate; no need to fixate on numbers. Nonetheless, the results are useful in helping to quantify the effects of perspective.
The chart shows the relative heights of the two compared cards and the magnification factor. For example, at 2 feet, the ear and nose cards measured 26.25 and 32.8, respectively, meaning that the tip of the nose was 1.25 times, or 25 percent, larger than the ear, whereas at 6 feet (and even less), the difference in magnification is negligible, although an extended hand, if included, would still appear magnified about 25 percent larger than the face.
Again, these are not offered to suggest rules; they are merely observations for my work that may be useful to some others.
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