Getting the right proportions onto the canvas is a key to creating a pleasing painting.
For a beginning artist, getting the right proportions on the canvas is one of the most common problems. A minor miscalculation can change a sparrow into a hawk or a cute little dog into a hunkering bear. There are a few quick tricks that can help any artist make sure that the painting's proportions are correct.
Distance Proportions
When you are sketching out your initial drawing for your painting, it helps to use a visual device to help you determine the spacial relationship between the objects you are painting. Hold your pencil out in front of you at arms length and measure each object in your composition. The relationship between the real world objects and those on your canvas should be in the same proportions. If a barn takes up one half of your pencil and a cow takes up one quarter, then on the canvas the barn should be twice as big as the cow. Use your thumb to mark the visually measured points. The key here is keeping your arm straight when you measure. A bent arm is not a consistent measuring length.
Shadow Proportions
Once you've placed the first shadow on the canvas, all other shadows must conform to the proportions given by that shadow (unless you have multiple light sources in your painting). Measure the length of the shadow and divide it by the length of the object which cast it. Use this value to determine the length of all subsequent shadows by dividing the object height by the number you got in your initial calculation. If you have multiple shadows, you can use this technique to determine the lengths of those shadows as well but not the intensity.
Human Body Proportions
You can use the head of a human body to determine the lengths of other facets. This means that once you've determined the size of the head of a subject, all other parts will fall into nice proportions. The shoulders will be three heads wide, the length of the elbow to the fingertip is two heads, the wrist to the fingertip is one head, the entire body is seven heads high (including the head), the hips rise up four heads, and the pelvic region is about one head high.
The Rule of Thirds
Determining the number of focal points in a painting and where to place them fall into the design proportion category. The "rule of thirds" is an ancient Greek artistic composition rule. It states that you should divide your canvas into three equal vertical and three equal horizontal regions. This will look like you've divided your painting into a giant Tic-Tac-Toe board. The focal point of the painting should appear on one of the four points where the lines cross. This type of focus helps to imply movement and draws the viewer's eyes away from the center of the image. There can be multiple focal points as long as they seem to be moving in equal and opposite directions.
