Why a Wide Angle Lens?
Lets compare a wide angle lens to a "standard" 50mm lens. A standard lens (also referred to as a normal lens) provides a view like the one you see with your eyes. A standard lens is a non-zoom lens, but it does allow for a broad range of aperture (light) which allows for pictures in low light. It's a great all purpose type lens. The wide angle lens offers something completely different than a standard lens. The wide angle sees more than the naked eye, it sees wider and takes in more picture than a standard lens. Each wide angle lens is made to take in a specific range of view and sometimes the range is so incredibly wide it is referred to as a super wide-angle and even an ultra wide-angle. The widest wide angle lens is called the fish-eye lens. This lens is so wide in its view that it distorts the image, giving it a rounded, fish-bowl appearance.
Using a Wide Angle Lens
A wide angle lens comes in fixed focal lengths (the distance from the lens to the point of focus)---35,28,24,18, or 14 mm. The focal length adjusts the visual relationships of the objects within the picture. The focal length identifies the angle being viewed. Think of a circle with a dot in the center. Now imagine drawing a slice into the circle, a V-shape with its bottom point being the dot. The area inside the V-shape is the angle being viewed and it becomes narrower or wider depending on which focal length chosen. If you stand in the same spot at the center of the circle and change the lens back to a standard lens, the pie shape becomes very narrow. A telephoto lens becomes a small channel and a wide angle lens gets wider.
Focal Length and Distance
Using an 18mm wide angle lens gives the picture a 100 degree angle (pie slice) and begins focusing at .85 of a foot. Using a 35mm wide angle lens gives the picture a 62 degree angle and begins focusing at 1 foot. The shorter the lens, the wider the angle. An 8mm fish-eye will produce a 180 degree view (that's half a pie) and begins focusing at about .9 of a foot.
The Parts of the Lens
A single-lens reflex (SLR) camera uses a wide-angle lens design called the retrofocus lens. This is an asymmetrical lens design that puts the rear lens element further away from the film plane than one would expect. An 18mm actually sits at about 25mm in the lens. A second type of design called the short-focus lens cannot be used on a 35mm SLR because it would come too close to the reflex mirrors contained in the camera. The short-focus lens is made up of glass elements that are mostly symmetrical on either side of the diaphragm (aperture) but because the SLR needs minimum clearance between the lens and film, the retrofocus design is used for SLR camera and the short-focus design is used on large format cameras.
Tags: angle lens, standard lens, wide angle, wide angle lens, Angle Lens