Despite all the ways people have advised us against it, you are totally free to go ahead and see Fifty Shades Of Grey if that's what your heart desires. But, PopSci reminds us that humans can't actually see 50 shades of gray — you know, the color? — in real life. According to a rough estimate, humans can view about 30 shades of the color gray, although some of us may be blessed with the ability to see a few more. And, it depends on viewing conditions, including lighting and the gray surface's texture. In general, we do better with color, PopSci says. The color receptors (cones) in our eyes come in three different varieties: red, green, and blue. Using our six million cones, we can see about a million colors, some estimates say; others put that number closer to 10 million. A few super-special people can see even more. From there, though, the way we interpret color is a more personal thing, and men and women tend to perceive color differently. Then, there's all that stuff about how your own memories and associations shape what you see, making it more likely that our internal experiences of color are specific to each of us, even if we all agree that "blue" is blue. So, whatever kind of gray (or Grey) you see, just know that it's all yours.