LENSES

Note: The information in this section refers mainly to the 35mm format.

The wide angle lens is one with a shorter focal length than the normal lens and has a field of view that is wider than the normal lens.
The angle of view of a 28mm wide angle lens is about 75°, compared to 46° for a 50mm lens

Wide angle lenses have focal lengths of between 15 and 35mm. They have the affect of reducing the size of the image on the film plane, so they include more of the scene in the image than the standard lens when used at the same camera position. This can create a sense of space particularly useful in landscape work.
Wide angle lenses have a greater depth of field (DoF) and will be in focus over a wider range for a given aperture, and as result focussing is less critical than with a normal lens.

The wide angle lens, is a fast lens, with a large maximum aperture, in the range of ƒ/1.4 and ƒ/1.8, allowing you to take pictures in low light with reasonably fast shutter speeds. Due to its greater DoF it is easily-focused, it is capable of excellent resolution and color rendition. Some have macro capability, making them useful for close up work but care needs to be taken to avoid distortion of the image.

Typical 28mm f1.4, Wide Angle lens.

16mm f2.8 Fisheye lens.

The wide angle lens is useful when working in confined areas or when one cannot get all the subject in the frame with a normal lens.

The view on the left of Nicosia, is a typical wide angle shot.
Taken with a 28mm lens it gives a much wider view of the city. The use of a small aperture with the extended DoF ensures that both the foreground and background of the image are in focus.
The blue rectangle shows the image that would be obtained with a normal (50mm) lens, taken from the same position.
The picture of the building could not have been taken from this position with a normal lens, shown by the blue rectangle, and moving further away to get all of the building in the frame would have allowed other objects to intrude into the foreground.
Bear in mind that with architectural shots, tilting the camera will cause the verticals to converge excessively, which will make the building appear to be leaning away from the camera. This is not neccesarily a problem as with some subjects it is a technique that can be used to good effect.

Photographs taken with a wide angle lens will have an extended angle of view, and can be used to create an apparent distortion of perpective. This can be used to good effect when used close up to the subject, making the the parts of the subject near to the camera appear much larger relative to those further away.

The photograph of the steam engine was taken with a 28mm lens.
It shows how a wide angle lens exaggerates the parts of the subject that are closer to the camera making the engine appear more massive and emphasizing the power of the engine.
By using a 28mm lens this small church in Cyprus has been made to look larger than it really is.
By getting in close to the nearer corner of the building it appears larger in proportion to the further corner, which appears further away, making the building appear larger.
The extended DoF of the 28mm lens ensures that all the image is in focus.
Notice how due to the camera being tilted, the front of the church appears to be leaning back slightly.

Lenses with focal lengths less than 15mm (commonly known as fish-eye lenses) produce circular images with up to 220° angle of view. The image exhibits extreme distortion and every straight line in the image appears curved.

Using a wide angle lens in portrait format for landscape work can create a feeling of space and height, as can be seen in this cloudscape.
Right hand picture illustrates the effect of a very short focal length 'fisheye' lens. The image is extremely distorted with noticeable curvature of all straight lines. Lenses of this type have very limited use but can be effective with certain subjects.

The diagram, left, shows the depth of field for
a typical 28mm lens at various apertures when
focussed on a subject at 5 and 15metres.

Note the extreme DoFcompared to the normal lens

Conclusion.
The wide angle lens is a useful for those situations where a normal lens will not cover the field of view required. It is particularly good for open landscapes and its greater DoF makes it ideal where the subject extends away from the camera.
Care must be taken with architectural shots as tilting the camera will cause all vertical lines to converge, making the building appear to be leaning backwards.
It is not an ideal lens for portraiture, as it will cause noticeable distortion of facial features, especially in close-ups.