A camera obscura can help students of drawing trace outlines of their subject. The camera obscura can aid students of drawing in learning proportions, angles, perspective, and forshortening. To make an obscura you will need a light source, such as a window, and a wall or screen opposite to the window. You will need to block out the light from the window with a piece of cardboard or thick fabric with a small hole cut in the center. The hole can be fitted with a lens, which can be borrowed from an old toy telescope or flashlight. An alternative to the open obscura is a box construction. The box can be constructed of wood or cardboard. This version is constructed with a lens on one end and a hole cut into the top back with a mirror placed inside at a 45 degree angle. To learn more, read:
Vermeerβs Camera: Uncovering the Truth Behind the Masterpieces