The difference between form and shape
We use the words “form” and “shape” interchangeably. There is however a distinction. This article What Is the Difference Between Shape and Form In Photography provides a basic explanation that distinguishes between the two, and how they correlate to the concept of “space” and how, when combined, creates the element of photographic composition. We’ve been exposed to shapes early on – triangles, rectangles, squares and those with many sides (hexagon, pentagon, etc.). In a photograph, an object comes across as two-dimensional. In the accompanying photo, we know the shape of the ball, in the same manner that we know the shape of a wheel, a plate, saucer, a complete pizza, a coin as examples. When viewed flat, they are all round or circular in shape. When light falls on the subject, like the ball in the picture, it produces dark areas and shadows, highlighting its length, width and depth, and producing a three-dimensional form with the negative space around it. Learning to use this concept of space in combination with the shape and form of central subjects will help in determining the viability and effectiveness of our composition. We know the shape of a tree. When we photograph that tree with the light of a sunset in the horizon, it will cast long shadows and create a dramatic form. Composition comes to fore when we combine our focal point (the tree, already in its interesting form) with other elements in the space around it, say distant mountains in the background or a verdant field surrounding it. The thinking photographer already envisioned the scene, and it is a matter of arranging these elements in the frame to come up with a compositionally pleasing shot.