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. A lens is generally considered a "pancake lens" when the length of the lens barrel is thinner than 30.0 millimetres (1.18 in).
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 further 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 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.
An early example is the (Zeiss) Tessar of 1902.
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.
List of Pancake Lenses
|Canon EF-S 24mm F2.8 STM||Prime||APS-C||22.9 millimetres (0.90 in)|
|Canon EF 40mm F2.8 STM||Prime||35mm Full Frame||22.8 millimetres (0.90 in)|
|Fujinon XF 27mm F2.8||Prime||APS-C||23.0 millimetres (0.91 in)|
|Nikon 1 NIKKOR 10mm F2.8||Prime||CX||22.0 millimetres (0.87 in)|
|Nikon 50mm F1.8 E AIS||Prime||35mm Full Frame||28.0 millimetres (1.10 in)|
|Olympus 14-42mm F3.5-5.6 EZ||Zoom||Micro Four Thirds||22.9 millimetres (0.90 in)|
|Olympus 17mm F2.8||Prime||Micro Four Thirds||22.0 millimetres (0.87 in)|
|Olympus 25mm f/2.8 ED||Prime||Micro Four Thirds||23.5 millimetres (0.93 in)|
|Panasonic Lumix G Vario 12-32mm F3.5-5.6||Zoom||APS-H||24.0 millimetres (0.94 in)|
|Pentax DA 21mm F3.2||Prime||APS-C||25.0 millimetres (0.98 in)|
|Pentax DA 40mm F2.8||Prime||APS-C||15.0 millimetres (0.59 in)|
|Pentax DA 40mm F2.8 XS||Prime||APS-C||09.14 millimetres (0.360 in)|
|Samsung NX 16mm F2.4||Prime||APS-C/DX||24.0 millimetres (0.94 in)|
|Samsung NX 20mm F2.8||Prime||APS-C/DX||25.0 millimetres (0.98 in)|
|Samsung NX 30mm F2.8||Prime||APS-C/DX||22.0 millimetres (0.87 in)|
|Sony E PZ 16-50mm F3.5-5.6 OSS||Zoom||APS-C||29.9 millimetres (1.18 in)|
|Sony E 16mm F2.8||Prime||APS-C||22.6 millimetres (0.89 in)|
|Sony E 20mm F2.8||Prime||APS-C||20.4 millimetres (0.80 in)|
|Voigtlander 40mm F2.0 Ultron SL II||Prime||35mm Full Frame||24.5 millimetres (0.96 in)|