Mossy Oak Obsession: a green-leaf pattern ideal for early-season hunts. Photo by Rod Hunter.

You've spent the last hour slipping quietly through a massive stand of oak trees. You were careful to keep the wind in your face, move slowly, and pause frequently. Stopping next to the trunk of a mature oak, you scan the large clearing in front of you. A slight movement 50 yards ahead catches your eye. You freeze, just as an 8-point buck pokes his nose out of the brush.

The buck quickly scans the clearing, his gaze moving to you, pausing briefly, and then moving on. A second later, convinced that all is well, he steps into the clearing.

That's the good scenario.

The bad scenario is that the buck locks his eyes on you, snorts once, and bolts back into the brush.

Which scenario plays out depends on what that buck sees as his eyes sweep across you.

Just what a white-tailed deer sees when it encounters a hunter in the woods has been a matter of considerable debate, and quite a bit of study. Do deer see the same colors we do? Do they see them under the same lighting conditions we do? Do they see the same degree of contrast we do?

The best available scientific evidence would suggest that the answer to all of those is: not exactly.

As with the human eye, the retina of the white-tailed deer's eye is furnished with cells known as "rods" and "cones" The cones are what mammals use for bright light, daytime vision, while the rods come into play in the very dim light of dusk or night. In humans, a lack of visible light causes the cones to retract slowly and the rods to extend, providing what is commonly referred to as "night vision." For a human with normal vision, this usually takes about 45 minutes. Any harsh white light almost immediately reverses the process.

Deer have the same basic physical eye structure, but with a twist. All aspects of normal color vision depend upon the photoreceptors present within the rods and cones. These determine what wavelengths of light from the spectrum are recognized and processed. Without getting into serious scientific verbiage, a whitetail's rods are similar to those in most other mammals' retinas. That's not a factor, since legal deer hunting doesn't occur after dark.

The whitetail's cones are another matter: The deer actually have two sets of cones. The photo pigments that process the light spectrum in one set are maximally sensitive to the middle wavelengths, while the other set shows peak sensitivity to the short wavelengths; thus, while the longer red-to-orange wavelengths are not seen well, the shorter blue wavelengths are perceived as vivid. In layman's terms, white-tailed deer -- according to the best scientific data available -- exhibit the same type of "color blindness" that some humans do, seeing blues as blues, and the rest of the visible light spectrum as some degree of yellow. Their vision is basically "dichromatic" -- they see their world in two basic colors.

That, however, is in standard daylight. When light levels are low during dawn and dusk, the short wavelength photo pigments kick in and deer begin to see the blue wavelengths that are heavy on ultraviolet light. Humans can't even see these. This light wave is perceived as bright blue in the two-color world of the deer and can be very intense. Deer still see in, basically, two colors. But, objects that reflect a great deal of UV light stand out vividly against surroundings that do not also reflect it.

On the surface, it would seem that the precise colors of a hunter's garment are not overly critical. Both blaze orange and popular green/ brown camo patterns blend in with green leaves, brown tree trunks, yellow grass, and other natural items because all would be seen as some shade of yellow by the deer.

Unfortunately, color is only one factor in the ability of a hunter to disappear. Deer can still see shapes, patterns, degrees of brightness, and movement. They invariably know their home turf as well as we know our own houses, so when they see something out of place, they tend to react the same way we would: They look more closely and investigate it.

Color factors aside, becoming invisible is best achieved by not appearing out of place.

Deer hunters have been trying to do that for years as part of their sport. The military has also studied the matter in depth as part of their survival training. When they teach the art of camouflage to the troops they start with three Ss -- Shape, Shine, and Silhouette. Irrespective of the colors one is wearing, each of these three factors can quickly give you away if they are ignored.