WE’VE ALL SEEN THE CARTOON of the artist in beret holding out his thumb with one eye closed. He is using his thumb as a measuring stick. If a house in the landscape is the height of the thumb, and another house is half a thumb tall, then it easier to paint them accurately: two to one in height.
Down to the present, painters still rely on such techniques. They typically hold out a brush handle and measure, say, the height of a person’s head in relation to width of shoulders, or length of torso. At the least, this gives a numerical grasp of how things relate, especially if it’s difficult to calculate in the visual abstract.
The common alternative is to forego all measurement and begin a trial-and-error process. Here, the painter wings it, putting down reference points, dabs, and lines and then, back and forth, adjusts them all to match what the painter is seeing.
It would seem that the two choices are a matter of "live and let live." But in the inside-baseball world of painting, the question of measuring has often become a heated debate—and a matter of pride.
Two extremes define the dispute. On one side is what has been called "sight-size" painting. Today, it is advocated at one notable art studio in Florence, Italy, and has had some academic art school advocates in the U.S.
Sight-size works best in portrait and still life, but can be applied to landscape. In the first two, the painter stands the canvas exactly next to the subject to make the visual measurements, and will make the painting the exact size of the subject. At this close range, using a held-out brush handle, for example, exact points and lines can be transferred from the subject to the blank canvas. You can stand back and see the subject and the drawing on the canvas in the identical sizes.
Today, on the Internet, many painters display their just-completed outdoor landscape painting against the actual landscape, showing a perfect match-up, like a piece in the puzzle; this to is a kind of sight-size. Here, the painter stands back and aligns his painting marks with the distant landscape features around the canvas.
Either way, proponents of sight-size can be dogmatic. Yet it is also a common sense practice for its advantages. John Singer Sargent, no dogmatist for sure, positioned his canvas next to his subject while painting. When standing back, he could compare the two more precisely.
Perhaps the more doctrinaire advocacy of sight-size in some places over recent history has produce bitter critics of it as “not true” painting. True painting, in this second extreme, says painting is a matter of assessing relationships of elements, and working them out on canvas by trial and error. A top figure painter at the celebrated Studio Incamminati in Philadelphia once was asked whether it was helpful to hold up a brush handle to measure proportion. "We don't do that here," he said. Jokingly, he recommended the "superpower" of drawing abstract relations.
He is referring to what is called the abstract, constructive, analytical, or relational “method” of drawing and painting. This, too, can tend toward a dogmatic creed. One favorite is to evoke the painter Claude Monet, who put down marks and colors all across the canvas until, changing and adjusting, all the elements settled in place.
There are other techniques that take a more middling path. The portrait Painter John Howard Sanden advocates four opening steps to begin a painting: Put down marks to position the size of the subject, draw the basic angles of the head, establish the central top-to-bottom line of the face, and define the negative space (i.e. background).
In another example of measurement techniques, one top watercolorist begins with the thumbnail sketch. He starts with a focal point—a single point—in the scene, then develops its linear perspective lines going outward to suggest the size and angles of other objects. Only after those lines are in place does he define the edges of the painting (in other words, he could crop it smaller or larger in the thumbnail sketch).
Then there’s the grid. In the old days, painters would produce a "cartoon," or large corrected and perfected drawing, and then draw grid lines over it. To enlarge the drawing on a mural-sized surface—canvas or wall—a similar grid was inscribed. This way the painter could replicated his prefect drawing on a larger scale.
Some painters, who need no measurement techniques, do have the remarkable "superpower" of abstracting exact relationships of images "out there" and replicating them. It’s often trial-and-error, and often a fast-and-sure process. Other painters clearly don't have the superpower.
For such mere mortals, some tools of measurement are eminently useful. They are not crutches, so to speak, but a tool like any other. To put up a brush handle to get a rough sense of proportions is not full-blown "sight-size" technique. It’s a way to start. Degas and Sargent used a straight edge to get their basic lines correct.
Such debates over sight-size versus relational eyeballing are just part of the rivalrous, inside-baseball art world, even among sanguine painters. It’s not only in art practice. As a Harvard academic once put it, "The smaller the disagreement on an academic point, the greater the passions."