Article about Ray diagrams for converging (convex) lens
If an object is on one side of the convex lens, the convex lens can form the image of the object. If the position of the object on one side of the convex lens is known, how to draw the image formation of the object? Suppose an object is on the left side of the convex lens, as shown below.
Orange line = convex lens
Blue line = principal axis
Arrow (green) = object
F1 = focal length 1 and F2 = focal length 2
Orange line = the concave lens