I copied this from the Outdoor Channel. In addition to being dichromatic, able to see far fewer colors than most humans, The have poor detail rendering, 20/200 in human terms, and only see in a narrow horizontal band.
"Another major difference between human and deer vision is visual acuity, which is the ability to focus on fine detail. Humans have an area on the retina called the optic fovea, a retinal depression with a high concentration of cone cells. Furthermore, about half of humans’ optic nerves are connected to the fovea. This combination gives us the ability to see fine detail, especially for activities such as reading, driving or watching television.
In contrast to a human’s round pupil and concentrated cones on the optic fovea, a deer’s horizontal-slit pupil and retinal structure give them a “visual streak” with areas of concentrated cone cells. As the concentration of cone cells on the retina increases, so does the ability to see detail. Deer have much less concentration of cone cells than humans, which means they don’t see the same fine detail. Research out of the University of Georgia points to deer vision being in the range of 20/200, which means a deer should be able to see detail at 20 meters that a human eye can see at 200 meters. That’s the same as a legally blind person.
Because of the horizontal pupil and cone concentration along the visual streak, scientists believe deer probably see greater detail along a horizontal swath in the middle of their field of vision. For an idea of how this might look from a deer’s perspective, imagine a television screen divided into horizontal thirds, with the screen’s mid"
- See more at:
http://outdoorchannel.com/article.aspx?id=3531&articletype=article#sthash.3MCzkm6H.dpuf