Maybe the only lens you need.
For most of the early days of photography, cameras either had one lens – permanently attached – or were typically sold with one fixed focal length lens. [“Fixed focal length” means ‘non-zoom’, with only one length setting] If the camera was an ordinary 35mm, the lens was almost always 50mm, what is called a “normal lens.” For medium format camera, a normal lens is usually 75mm or 80mm.
How “normal lens” is defined
The normal lens is determined by the size of the film area (or sensor area, in the case of digital cameras). Whether rectangular (like a 35mm Nikon), or square (like a 2 1/4” Hasselblad), the length of the diagonal determines the length of a normal lens. For example, 35mm film is 24mm x 36mm in size. Our old friend Pythagoras figured out that c2 = a2+b2. So 35mm works out to 43.26mm. Manufactures round up to 50mm, as a little bit of extra length works out for most situations (in the past, some made 43mm lenses, but this was uncommon). For a 2 1/4” square, the diagonal is 80.82mm, so almost exactly matching the normal 80mm length.
Characteristics of a normal lens
For a lens design standpoint, normal lenses are relatively straightforward, without too much complexity. They can be physically smaller and lighter than other lenses, and optically faster as well. [ed. Faster refers to the maximum aperture (the amount of light that enters the lens) – see future articles about lens “speed”] Normal lenses are usually cheap, and very good quality for their price.
It is said that, with regards to optical perspective, normal lenses most resemble the human eye. The sense of depth, the relationship of foreground and background, are similar to how we normally see.
Some people call 35mm normal lenses “nifty-fifiies” after their length. To my knowledge, there’s no equivalent for medium or large format cameras… no “awesome-eighties.”
Normal lenses are great!
I personally use a normal lens for most of my photography. The combination of light weight, fast maximum aperture, and high quality make the lens irresistible to me. I highly recommend spending some time shooting with one… and you might discover it works great for your images.
Article originally published on Startphoto on July 14, 2013.