The short answer is better than you do.
Way better. Then again, humans don’t need good night vision nearly as much as elk and other ungulates do.
Research on elk vision has focused more on their ability to perceive color than see in the dark, but here’s what we do know. The eye possesses two types of photoreceptors—cones and rods. Cones are primarily responsible for seeing color. Rods though, are much more sensitive to light. An animal with an abundance of rods can make maximum use of what light is available. Ungulates have a large number of rods in their eyes. They also have a special mirror in the back of their eyes that reflects captured light back through the retina. This mirror—which humans and other primates lack––is what creates “eyeshine” when you point a flashlight at an elk, deer, raccoon or bear. It also allows them to make better use of what light is present, be it moonlight or even just starlight.
(photo credit: David Neils)