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TheCanon EF-S lens mount is a derivative of theEF lens mount created for someCanondigital single-lens reflex cameras withAPS-C sized image sensors. It was released in 2003. Cameras with the EF-S mount arebackward compatible with the EF lenses and, as such, have aflange 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"[1] (the lens projects a smallerimage circle than normal EF lenses to match the sensor), or "Short back focus"[2] (the smaller mirror used in APS-C cameras also allows optical elements to protrude further into the camera body, reducing the minimum distance between the sensor and the back element of the lens). The combination of a smaller sensor and shorterback 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 (containing less glass), faster (largeraperture) and less expensive.
Although not all Canon EF-S lenses use this short back focal length, they cannot be mounted onDSLRs 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 noticeablevignetting or unsharp outer areas if used on a35mm film orfull frame sensor cameras. To a lesser degree, vignetting also occurs withAPS-H sensor sizes, such as several (now discontinued) cameras of the 1D series.
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 smallerimage circle of even illumination (circle of novignetting). 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 anextension tube; however, this does not eliminate the vignetting problem, and also removes the lens's ability to achieveinfinity focus.[3] 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.
The10D,D60,D30, and earlier cameras share theEF-only mount with the full frame EOS camera bodies, and also with theAPS-H size EOS camera bodies (1D series prior to the 1D X), despite having a smaller sensor and therefore a smaller mirror.
The EF-S lens mount is a relatively new offering from Canon, so 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. As of April 2017,[update] no EF-S lens has been produced with the"L" designation or withdiffractive optics, and only three EF-Sprime lenses have been produced.
| Focal length | Equivalent focal length (×1.6crop factor) | Maximum Aperture range | Mark | Introduced | Macro | USM | STM | IS |
|---|---|---|---|---|---|---|---|---|
| 10–18mm | 16–28.8 mm | f/4.5–5.6 | IS STM | 2014 | No | No | Yes | Yes |
| 10–22mm | 16–35.2 mm | f/3.5–4.5 | USM | 2004 | No | Yes | No | No |
| 15–85mm | 24–136 mm | f/3.5–5.6 | IS USM | 2009 | No | Yes | No | Yes |
| 17–55mm | 27.2–88 mm | f/2.8 | IS USM | 2006 | No | Yes | No | Yes |
| 17–85mm | 27.2–136 mm | f/4–5.6 | IS USM | 2004 | No | Yes | No | Yes |
| 18–55mm | 28.8–88 mm | f/3.5–5.6 | I | 2003 | No | No | No | No |
| I (Jpn.) | 2003 | No | Yes | No | No | |||
| II | 2005 | No | No | No | No | |||
| II (Jpn.) | 2005 | No | Yes | No | No | |||
| III | 2011 | No | No | No | No | |||
| IS | 2007 | No | No | No | Yes | |||
| IS II | 2011 | No | No | No | Yes | |||
| IS STM | 2013 | No | No | Yes | Yes | |||
| f/4–5.6 | IS STM | 2017 | No | No | Yes | Yes | ||
| 18–135mm | 28.8–216 mm | f/3.5–5.6 | IS | 2009 | No | No | No | Yes |
| IS STM | 2012 | No | No | Yes | Yes | |||
| IS USM | 2016 | No | Yes | No | Yes | |||
| 18–200mm | 28.8–320 mm | f/3.5–5.6 | IS | 2008 | No | No | No | Yes |
| 55–250mm | 88–400 mm | f/4–5.6 | IS | 2007 | No | No | No | Yes |
| IS II | 2011 | No | No | No | Yes | |||
| IS STM | 2013 | No | No | Yes | Yes | |||
| 24mm | 38.4 mm | f/2.8 | STM | 2014 | No | No | Yes | No |
| 35mm | 56 mm | f/2.8 | IS STM | 2017 | Yes | No | Yes | Yes |
| 60mm | 96 mm | f/2.8 | 2005 | Yes | Yes | No | No |
