Wide Angle Lens
At one time a 28mm lens was considered to be a wide angle camera lens. That was when a 50mm lens was standard on all cameras. As optics improved, due to the use of computer aided design, lens kept getting wider. Now a 12mm is common, along with wide angle zoom lenses. Speeds of f/3.5 to f/4.0 are available at moderate prices.
The real incentive for using a wide angle camera lens is the tremendous depth of field. It will focus as close as 12 inches, and at 5 feet to infinity. That opens up a considerable new realm of photography. A wide angle camera lens is also less unaffected by camera shake or vibration that a longer focal length lens. Shutter speeds of 1/10 of a second are feasible without any noticeable blur.
Now for the trade-offs. Due to design, wide angle lens are not as sharp as a longer focal length lens. The wider they get, the more this is true. Speeds stops at about f/3.5. Flare can be a problem. Lens hoods must be sizeable to keep from cutting off at the corners or vignetting.
This might sound bad, but if you are careful, and understand the problems, and how to counteract them, you will be guaranteed to get surprisingly good photographs. If you remember, parallel or vertical lines will tend to converge. If you are using a12mm, if not careful, your shoes will be in the picture.
