A pancake lens is colloquial term for a flat, thin

camera lens A camera lens (also known as photographic lens or photographic objective) is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capa ...

assembly (short barrel). The majority are a prime lens of normal or slightly wider

angle of view The angle of view is the decisive variable for the visual perception of the size or projection of the size of an object. Angle of view and perception of size The perceived size of an object depends on the size of the image projected onto the ...

. Some are zoom lenses.

Motivation

Pancake lenses are primarily valued for providing quality optics in a compact package. The resulting camera and lens assembly may even be small enough to be pocketable, a design feature which is usually impractical with conventional SLR bodies and lens assemblies. Pancake lenses can be very short and flat because they do not need large amounts of optical correction, i.e. extra lens elements. The problem arises when such lenses have too short a

focal length The focal length of an optical system is a measure of how strongly the system converges or diverges light; it is the inverse of the system's optical power. A positive focal length indicates that a system converges light, while a negative foca ...

to fit in front of the retractable mirrors used in reflex cameras. In such a situation, a pancake lens focuses in front of, rather than on, the

focal plane In Gaussian optics, the cardinal points consist of three pairs of points located on the optical axis of a rotationally symmetric, focal, optical system. These are the '' focal points'', the principal points, and the nodal points. For ''ideal'' s ...

(film or light sensor) of the camera. This has necessitated the design of retrofocus lenses that refocus the image farther back, which is why such lenses are longer and bulkier than their "pancake" equivalents. Pancake-style prime lenses are generally simpler to manufacture than pancake zoom lenses like Sony E PZ 16-50mm F3.5-5.6 due to the general lack of an internal micromotor and fewer image correcting elements, allowing for a thinner profile. Because of this limitation, pancake zoom lenses are much less common. While there is no specific size and weight in defining a pancake lens, most are light-weight and no more than a few centimeters in length. This varies g