What a surprise for me when I finally realized how small most daily paintings are. Looking through blog after blog of these little jewels, I automatically sized them mentally at least as large as 9" x 12". I could plainly read 6" x 6" or 5" x 7" or even "postcard," but this data failed to translate into true perception until one of the bloggers showed his little daily side by side with a coffee mug.
Light bulbs! Either the mug is huge or the painting is teeny, which brings up the first requirement for size as a visual element: Size requires clues--there must be a comparison, else size doesn't translate.
Size and Proportion
Seeing a photo of a marble or a tennis ball singularly tells us absolutely nothing about the size of either, but a photo of the two spherical objects together tells us about the size of both because we can see their relative proportion to each other.
We can draw the human body's proportion accurately by comparing the length of the head to its other parts. Keeping all the parts' sizes relative to the head (or any other part for that matter) will guarantee we render individual parts the right size therefore enabling us to create a human image in proportion to itself.
Leonardo shows this in a diagram he did for us with his famous Proportions of Man.
In fact, just as the proportion of ingredients in cooking determines the flavors in food, proportion of sizes plays an important spatial role for every artwork we make whether drawing, painting, or sculpting. Once we make the first shape, the size of every shape to follow will affect and will be affected first shape we made.
Size and Proximity
One way size affects shapes is to show their distance from one another. Our vision is such that the further away a thing is, the smaller we see it compared to anything in front of it. Looking out my window I can see trees. I can hold up one finger and totally block out a tree not thirty feet away from me. The same finger can block out five trees a hundred feet away. My finger is certainly much smaller than any of those tree trunks, yet its proximity to my eyes makes it appear larger by comparison.
In the above painting by Richard Schmid, the height of figure (Nancy) measures a little taller than the huge boulders behind her. That size puts Nancy closer to us and the boulders further away, showing them to be some distance behind her. If Schmid had painted Nancy within a couple of feet of the boulders, in the painting they would dwarf her in size. That's called size relationship.
Size and Foreshortening
But size plays yet another role-- it also enables us to foreshorten. So what does it mean to foreshorten and why is it important to know?
(To stray a bit), prowling the internet, I was hoping to find a clear explanation for foreshortening, but all I could find was a lot of dense rhetoric that I think fails to communicate exactly what foreshortening does. So let's begin with an illustration. Look below at the two photos of the same male cardinal.
The photo on the right is a side view where we can perceive the bird's full length head to tail. The other is a rear view where we can see his tail and his head, but we see them substantially closer to each other than in the side view. In the rear view, the space between the cardinal's head and tail is foreshortened.
The space between two ends of an image is shortened any time the image's length is other than parallel to our eyes.
Here's another example. Notice the cow on the left, more parallel to our eyes. Its measured length head-to-tail is greater than the length head-to-tail of the cow on the right.
Because the middle cow's rear end is closer to our eyes than its head, we see it shorter from head-to-tail than the cow on the left, but longer than the cow on the right whose backside is much further from our eyes than its head. So how much a thing is foreshortened depends upon the proximity of each it's two ends to the viewer's eyes.
Head spinning? Not to worry. None of this is necessary to know if you're a keen observer of what your eyes are actually seeing rather than what your left brain tells you you're seeing. However, when we know this stuff, we can feed it to the left brain so that it will reinforce what our right brain is responding to.