# Object / Image relationship

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What is the relationship between the object and image distances if their sizes are in the ratio 1:1?
Assuming we are talking about a convex lens. From the ray diagram of a convex lens (below), we can see that the ratio of object and image distance is equal to the ration of the object and image heights: $$\frac{s_o}{s_i}=\frac{h_o}{h_i}$$.