Canon EF-S lens mount

The Canon EF-S lens mount is a derivative of the EF lens mount created for some Canon digital single-lens reflex cameras with APS-C sized image sensors. It was released in 2003. Cameras with the EF-S mount are backward compatible with the EF lenses and, as such, have a flange focal distance of 44.0 mm. Such cameras, however, have more clearance, allowing lens elements to be closer to the sensor than in the EF mount. Only Canon cameras released after 2003 with APS-C sized sensors support the EF-S mount.
The "S" in EF-S has variously been described by Canon as coming from either "Small image circle", or "Short back focus". The combination of a smaller sensor and shorter back focal length distance enhances the possibilities for wide angle and very wide angle lenses. Such lenses designed for the EF-S mount can be made smaller, lighter, faster and less expensive.
Although not all Canon EF-S lenses use this short back focal length, they cannot be mounted on DSLRs with sensors larger than APS-C. However, some lenses produced by third-party manufacturers may feature the standard EF mount if they do not have the shorter back focal length but only have a small image circle. Such lenses will give noticeable vignetting or unsharp outer areas if used on a 35mm film or full frame sensor cameras. To a lesser degree, vignetting also occurs with APS-H sensor sizes, such as several cameras of the 1D series.

Compatibility

The cameras that can use the EF-S mount are:

By design, it is physically impossible to mount EF-S lenses on EF-only cameras. This is because the increased proximity of the lens to the sensor means that on full-frame sensor or 35mm film EF cameras the lens itself would obstruct the mirror's movement and cause damage to the lens and/or camera. While it is possible to modify the lens such that the physical obstruction is removed, allowing for mounting to EF mount cameras, the rear of the lens would still obstruct the mirror. An additional reason is that the lenses produce a smaller image circle of even illumination. An EF-S lens alignment mark is indicated by a small white rectangle, whereas the EF employs a small red dot. The lens will insert into the body when the alignment marks on each are matched, and the lens can then be rotated and locked into the operating position. EF-S camera bodies have both EF-S and EF alignment marks, while EF bodies have only EF marks. Some have reported success attaching EF-S lenses to full-frame bodies with the use of an extension tube; however, this does not eliminate the vignetting problem, and also removes the lens's ability to achieve infinity focus. Also, attachment of EF-S lenses on EF bodies can often be accomplished by removing the small plastic ring seen in the photo above. Although vignetting is still an issue, photos can be taken, and infinity focus achieved. This modification comes with caveats, one being that on some lenses, like the EF-S 10-22mm, at the 10mm setting, the element protrudes too far back toward EF mount camera bodies.
The 10D, D60, D30, and earlier cameras share the EF-only mount with the full frame EOS camera bodies, and also with the APS-H size EOS camera bodies, despite having a smaller sensor and therefore a smaller mirror.

List of EF-S lenses

The EF-S lens mount is a discontinued offering from Canon, and the selection of available lenses is limited compared to the full EF range, but it is backward compatible with the EF mount, and can therefore still accept all EF lenses. The variety of EF-S prime lenses is very limited in comparison to EF-S zoom lenses, with three primes to nine zooms. EF-S lenses are very popular due to their lower cost and zoom lenses are preferred by amateur photographers. no EF-S lens has been produced with the "L" designation or with diffractive optics, and only three EF-S prime lenses have been produced.

Focal length	Equivalent focal length	Maximum Aperture range	Mark	Introduced	Macro	USM	STM	IS
10–18mm	16–28.8 mm	4.5–5.6	IS STM	2014
10–22mm	16–35.2 mm	3.5–4.5	USM	2004
15–85mm	24–136 mm	3.5–5.6	IS USM	2009
17–55mm	27.2–88 mm	2.8	IS USM	2006
17–85mm	27.2–136 mm	4–5.6	IS USM	2004
18–55mm	28.8–88 mm	3.5–5.6	I	2003
18–55mm	28.8–88 mm	3.5–5.6	I	2003
18–55mm	28.8–88 mm	3.5–5.6	II	2005
18–55mm	28.8–88 mm	3.5–5.6	II	2005
18–55mm	28.8–88 mm	3.5–5.6	III	2011
18–55mm	28.8–88 mm	3.5–5.6	IS	2007
18–55mm	28.8–88 mm	3.5–5.6	IS II	2011
18–55mm	28.8–88 mm	3.5–5.6	IS STM	2013
18–55mm	28.8–88 mm	4–5.6	IS STM	2017
18–135mm	28.8–216 mm	3.5–5.6	IS	2009
18–135mm	28.8–216 mm	3.5–5.6	IS STM	2012
18–135mm	28.8–216 mm	3.5–5.6	IS USM	2016
18–200mm	28.8–320 mm	3.5–5.6	IS	2008
55–250mm	88–400 mm	4–5.6	IS	2007
55–250mm	88–400 mm	4–5.6	IS II	2011
55–250mm	88–400 mm	4–5.6	IS STM	2013
24mm	38.4 mm	2.8	STM	2014
35mm	56 mm	2.8	IS STM	2017
60mm	96 mm	2.8		2005