Wide-angle lens

This exaggeration of relative size can be used to make foreground objects more prominent and striking, while capturing expansive backgrounds.

[2] Longer lenses magnify the subject more, apparently compressing distance and (when focused on the foreground) blurring the background because of their shallower depth of field.

Wider lenses tend to magnify the distance between objects while allowing greater depth of field.

Another result of using a wide-angle lens is a greater apparent perspective distortion when the camera is not aligned perpendicularly to the subject: parallel lines converge at the same rate as with a normal lens but converge more due to the wider total field.

Because different lenses generally require a different camera–subject distance to preserve the size of a subject, changing the angle of view can indirectly distort perspective, changing the apparent relative size of the subject and foreground.

Ultra wide angle lenses have a focal length shorter than the short side of the film or sensor[citation needed].

Many of the lenses in this range will produce a more or less rectilinear image at the film plane, though some degree of barrel distortion is not uncommon.

Lens manufacturers have responded by making wide-angle lenses of much shorter focal lengths for these cameras.

Short-focus lenses are generally made up of multiple glass elements whose shapes are more or less symmetrical in front of and behind the diaphragm.

The retrofocus lens solves this proximity problem through an asymmetrical design that allows the rear element to be farther away from the film plane than its effective focal length would suggest.

A Canon wide-angle 17-40 mm f/4 L retrofocus zoom lens
How focal length affects photograph composition. Three images depict the same two objects, kept in the same positions. By changing the focal length and adjusting the camera's distance from the pink bottle, this bottle remains the same size in the image, while the blue bottle's size appears to dramatically change. Also note that at small focal lengths, more of the scene is included.
Field of view in APS-sized digital cameras is the same as that of a longer lens, increased by crop factor , on a full-frame 35 mm format camera.
Cross-section of a typical short-focus wide-angle lens.
Cross-section of a typical retrofocus wide-angle lens.
Effective focal length is measured from the sensor to where the light cone going to the sensor is the same size as the lens front opening.