Pancake lens

Apancake lensis a colloquial term for a flat, thincamera lensassembly (short barrel). The majority areprime lensesof anormalor slightly widerangle of view, but some arezoom lenses.
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 conventionalSLRbodies 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 afocal lengthto fit in front of the retractable mirrors used inreflex cameras. In such a situation, a pancake lens focuses in front of, rather than on, thefocal plane(film or light sensor) of the camera.  This has necessitated the design ofretrofocuslenses 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 greatly depending upon the lens' build quality, focal length, and maximum aperture.
In the 1960s and 1970s the Nikon GN lens was a notable example, while in the 1970s and 1980s pancake lenses were used in compactsingle lens reflex(SLR) cameras.
Throughout the 2010s, the design has seen a resurgence due to the growth of themirrorless interchangeable-lens digital cameramarket. Pancake lenses have increasingly become lighter and feature thinner profiles than years past. An extreme example of this trend would be thePentax DA 40mm F2.8 XS, released in 2012 and measuring only 9.14 millimetres (0.360 in) long.
Abody-cap lensis an extreme type of pancake lens that is designed to both protect the camera internals as a body cap normally would, yet still allow the user to take photos. These lenses are manual focus only and generally have no more than a couple of optical lens elements, no image correcting elements, a very-slow fixed aperture, an extremely thin focusing ring (if any), and a retractable lens element cover. Due to this compromise in design, body-cap lenses generally suffer from numerous image quality issues such as heavy vignetting and poor image sharpness.
Examples of body-cap lenses include the Olympus 9mm F8 Fisheye and Olympus 15mm F8 forMicro Four Thirdsand the Fujifilm XM-FL 24mm F8 forFujifilm X-mount.
Panasonic released a manual-focus lens for theL-Mountthat is nearly the size of a body cap, but it does not have a retractable lens cover: the Lumix S 26mm F8.
This is a list ofautofocusprime lensesdesigned formirrorless camerasthat measure less than 30 millimeters in length — limit one per brand andfocal lengthcombination.
In 2024, Viltrox released the thinnest autofocus pancake lens ever produced for full-frame sensors: a 28mm F4.5 lens that is only 15mm thick. It is closer in size to a body-cap lens than to other pancake lenses.
This is a list ofautofocuszoom lensesdesigned formirrorless camerasthat measure less than 33 millimeters in length.
This is a list ofautofocusprime lensesdesigned formirrorless camerasthat measure between 30 and 38 millimeters in length.
The term pancake lens also refers to a specific type of image forming lens used invirtual realityandmixed realityheadsets. This type of lens uses the principle thatcircular polarizationis flipped at reflections at optical boundaries to lengthen the light path across the lens. This enables shortening the distance between the eye and the screen, therefore making the goggles more compact.