in photography, a lens that is said to approximate closely what the human eye sees. It is normally a lens whose focal length is equal to the diagonal of the film format.
Thus for 35mm photography, where the photogram is 24 x 36 mm, the normal lens is sqrt(242 + 36 2) mm, being about 43 mm.
Interestingly enough, most "normal" lenses for 35mm cameras are in fact 50 mm, although 45 mm do exist (Pentax makes one).
What about other formats, says the Large Format dude, in chorus with the Minox freak ? A bigger piece of film means a longer normal lens.
- 6x6 (120 film) -> 80 mm
- 6x9 -> 110 mm
- 4"x5" -> 162 mm, I think that 180 mm is more usual
- 8"x10" -> 240 mm
And what about the Minox freak, you ask ? Well, he is shooting on an itty bitty frame of film, which means that his normal lens will be shorter. For a typical 8mm x 11mm negative, we have 14mm. Which also explains why on this kind of cameras you can almost dispense with focusing: the depth of field keeps everything in focus.
Contrast the normal lens with the telephoto lens and the wideangle lens. Of course, what I said above about the human eye should be taken cum grano salis, and should be adjusted to each person's perception.
I will probably write something about the human eye compared to a camera.
Uses of the normal lens
The normal lens is, always, a good, light and cheap lens. In fact, if you look at the ratio of lens_quality/dollars, the normal lens always wins, especially over zooms.
You might ask yourself, so why I am not getting one with my new camera ?
You must be talking about 35 mm low-end cameras, because professional cameras usually come with no lens at all (or, to see it more positively, with the lens you prefer).
The market wants zooms, because of their vast convenience and of their (apparent) ease of use - or, on some cameras, a mild wideangle (a 35 mm usually). In fact nobody makes a compact camera with a 50mm lens, because not enough people would buy it.
Over and over, it has been proven (by the 110 format, for example), that people will choose convenience over quality, over and over.
But you can be a wise guy, and you may become a better photographer: spend 100$, and get yourself a nice normal lens, if you don't already own one. Experiment with available light photography, and enjoy a light and responsive piece of glass.
Years will pass before you hit the limits of the normal lens.
Good photographers already know all this, and will excuse me for this rather obvious rant in favour of the normal lens. Large Format dudes, just chuckle and go back to your dark cloths, bellows and Velvia - OK ? :-)
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