Sorry, but there were some major factual inaccuracies in the second post:
Prime: Yes a prime is a fixed focal length lens... by definition, not a zoom. But it doesn't necessarily give you a "perspective" of the human eye. A 25mm prime is no more or less a prime than a 150mm fixed focal length, and obviously those two give two very different perspectives. In summary, a prime is simply a lens that has a fixed focal length. This is useful because since there is less glass, you generally get a sharper and more defined image. The rule of thumb is basically that the less glass in front of the lens, the less distortion (i.e. vignetting, color distortion, sharpness).
Zoom: A zoom lens does not inherently have greater depth of field than a prime. Depth of field is controlled by focal length (the longer the focal length, the less the depth of field), f-stop, and distance from subject. More accurately, a wide angle lens has greater depth of field than a telephoto lens. The fact that a lens zooms or not does not have anything to do with whether or not it has greater depth of field or not. Also, zooms do not "usually go from 18-200mm". There is a huge range of zoom lenses for every situation.
Wide angle lens: A wide angle lens is defined as any lens that is under 50mm. 50mm roughly simulates what one sees if one eye is covered, and is considered the middle ground that separates wide from telephoto (this is in 35mm standards...). Maybe the first post was in reference to 16mm cinematography... A 49mm lens, if such existed would be considered a wide angle lens. In the wide angle realm, you can get into fisheyes where there is controlled distortion, and other special effect lenses. On high end wide angle lenses, distortion is almost non-existent, and is primarily controlled 1. by the quality of the lens and the glass, and then 2. by the distance the lens is from the subject. The closer you are to a subject with a wide angle lens, and the wider the lens, the greater the distortion.
Telephoto lens: This is any lens that is over 50mm in focal length. They inherently give the ability to achieve a shallower depth of field. Telephotos compress objects in space, and can be used to make distant subjects appear much closer than actuality. The difference between a telephoto and a macro lens is as follows: A macro brings objects that are close even closer, whereas a telephoto brings objects that are far away, closer. This is an important distinction, because many telephotos have a minimum focus of at least 3 ft, although this varies with the focal length obviously.
Video Lenses: Whatever this really means..... Just to clear this up, a so-called "video lens" does not have any shallower or greater depth of field than a non-video lens. In this scenario, the depth of field is determined by the CCD inside the camera. Since most consumer and prosumer video cameras have extremely small sensor chips, there is greater depth of field. If you want a more complete answer on depth of field, ask M. David Mullin, who is a technical genius at this stuff (he'll probably start with the circle of confusion). I understand all the principles of depth of field, but have not internalized all of the concepts in such a way that I can express them verbally yet...
As far as things to remember, depth of field is affected by:
1. Distance of camera from subject
2. Focal length of lens.
3. F-stop
4. If more than one subject, distance between subjects in relation to camera.
I'd highly recommend checking out Blaine Browns book on cinematography, or also the new one by Kris Malkowitz and M. David Mullin is good as well. And also checking out cinematography.com, which is a phenominal resource of world class cinematographers sharing knowledge.
