Often when I show people pictures that I have taken using a wide-angle lens, they say - I really like pictures taken with a fish-eye lens. And indeed it is a widespread belief that pictures that have that wide-angle look are fish-eye images. However fish-eye refers to a very particular kind of lens and look that simulates the kind of view of the world that we assume that fishes have. This assumption about the way in which fishes see the world is based on the physical structure of a fishs eye (and the assumption that it only looks through one eye). Of course we dont have any idea about how a fish visualises the world, or even if that is meaningful way of thinking about a fishs perception. However, there is one very important difference in photography between that images produced by a fish-eye lens and those produced by a wide-angle lens. Both make images that show more of the world than the human eye naturally sees, sometimes much more, but a fish-eye lens shows real-world straight lines as curved lines, whereas a wide-angle lens (a so-called rectilinear wide-angle) shows real world straight lines as straight lines. Both exaggerate perspective, but critically, the fish-eye changes the shape of objects - particularly of objects near the camera. The fish-eye effect can be produced very easily, and you can buy cheap fish-eye lenses (and auxiliary lenses that fit on the front of existing lenses), although such lenses dont produce sharp images. (You can spend a lot of money on a fish-eye lens that produces pin-sharp images.) Rectilinear wide-angle lenses are typically quite expensive because the design is necessarily more complex. This much more easily shown than explained - the first image accompanying this post was taken with an 8mm fish-eye lens that cost less than £200 - lots of things in are curvy despite not being so in the real world. The second image was taken with an 8mm (rectilinear) wide-angle lens that cost over £600 - in this image straight lines in the real world end up straight in the picture
Posted on: Tue, 09 Sep 2014 11:55:00 +0000
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