Pancake lens

A pancake lens is a colloquial term for a flat, thin camera lens assembly (short barrel). The majority are prime lenses of a normal or slightly wider angle of view, but some are zoom 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 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 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 (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 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 compact single lens reflex (SLR) cameras.^[1]

Throughout the 2010s, the design has seen a resurgence due to the growth of the mirrorless interchangeable-lens digital camera market. Pancake lenses have increasingly become lighter and feature thinner profiles than years past. An extreme example of this trend would be the Pentax DA 40mm F2.8 XS, released in 2012 and measuring only 9.14 millimetres (0.360 in) long.

A body-cap lens is 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 for Micro Four Thirds and the Fujifilm XM-FL 24mm F8 for Fujifilm X-mount.^[2][3]

Panasonic released a manual-focus lens for the L-Mount that 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 of autofocus prime lenses designed for mirrorless cameras that measure less than 30 millimeters in length — limit one per brand and focal length combination.

This is a list of autofocus zoom lenses designed for mirrorless cameras that measure less than 33 millimeters in length.

This is a list of autofocus prime lenses designed for mirrorless cameras that measure between 30 and 38 millimeters in length.

This list is incomplete; you can help by adding missing items. (February 2017)

• 
  Olympus Pen F/FT (35mm analog film) lens E. Zuiko Auto-S 1:2.8 f=38mm 1966
• 
  Canon EF 40mm F2.8 STM pancake lens
• 
  SMC Pentax-M 40mm
• 
  Pentax DA 1:3.2 21mm
• 
  Sony E PZ 16-50mm F3.5-5.6 OSS pancake zoom lens

The term pancake lens also refers to a specific type of image forming lens used in virtual reality goggles. This type of lens uses the principle that circular polarization is 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.^[4]

• Kit lens
• Standard zoom lens

• List of all pancake lenses by camera format