Rods give us vision in dim light but not in color and not with sharp detail. They are hundreds of times more sensitive to light than cones, letting us detect shape and movement in dim light. This type of photoreceptor takes about 15 minutes to fully adapt to very dim light.
The structures of the human eye. 1 = Cornea; 2 = Iris; 3 = Lens; 4 = Anterior chamber; 5 = Canal of Schlemm; 6 = Ciliary body; 7 = Posterior chamber; 8 = Bony orbit; 9 = Macula lutea; 10 = Retina; 11 = Uvea; and 12 = Sclera. (From Pilliterri, Adele. Maternal and Child Nursing. 4th ed. Philadelphia: Lippincott, Williams & Wilkins, 2003.)