Canon EF-S lens mount

An example of a plastic EF-S lens mount.

The Canon EF-S lens mount is a derivative of the EFlens mount created for a subset of Canon digital single-lens reflex cameras with APS-C sized image sensors. Itwas released in 2003. Cameras with the EF-S mount arebackward-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 tobe closer to the sensor than in the EF mount. Only Canoncameras released after 2003 with APS-C sized sensorssupport the EF-S mount.The “S” in EF-S comes from “Small image circle”, mean-ing the lens is designed to provide a small (relative to anormal EF lens) image circle to match the sensor.[1] Thesmaller mirror used in APS-C cameras also allows opticalelements to protrude further into the camera body, whichenhances the possibilities for wide angle and very wideangle lenses, enabling them to be made smaller, lighter(containing less glass), faster (larger aperture) and lessexpensive.Although not all Canon EF-S lenses use this short backfocus, they cannot be mounted on non APS-C cameras.However, some lenses produced by third-party manufac-turers may feature the standard EF mount if they do notrequire the shorter back focus but only have a small im-age circle. Such lenses will give noticeable vignetting ifused on a 35mm film or full frame sensor cameras. To alesser degree, vignetting also occurs with APS-H sensorsizes, such as several (now discontinued) cameras of the1D series.

1 Compatibility

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

An EF-S compatible body, the Canon EOS 400D, with open lensmount

An EF-S compatible mount close-up, from the Canon 30D. Notethe circular indent inside the mount, which corresponds to theraised ring on the lens.

Canon designers have taken steps to ensure it is physi-cally impossible to mount EF-S lenses on EF-only cam-eras. This is because the increased proximity of the lensto the sensor means that on full-frame sensor or 35mm

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2 4 EXTERNAL LINKS

film EF cameras the lens itself would obstruct themirror’smovement and cause damage to the lens and/or camera.While it is possible to modify the lens such that the phys-ical obstruction is removed, allowing for mounting to EFmount cameras, the rear of the lens would still obstructthe mirror. An additional reason is that the lenses pro-duce a smaller image circle of even illumination (circleof no vignetting). An EF-S lens alignment mark is indi-cated by a small white rectangle, whereas the EF employsa small red dot. The lens will insert into the body whenthe alignment marks on each are matched, and the lenscan then be rotated and locked into the operating posi-tion. EF-S camera bodies have both EF-S and EF align-ment marks, while EF bodies have only EF marks. Somehave reported success attaching EF-S lenses to full-framebodies with the use of an extension tube; however, thisdoes not eliminate the vignetting problem, and also re-moves the lens’s ability to achieve infinity focus.[2] Also,attachment of EF-S lenses on EF bodies can often be ac-complished by removing the small plastic ring seen in thephoto above. Although vignetting is still an issue, photoscan be taken, and infinity focus achieved. This modifica-tion comes with caveats, one being that on some lenses,like the EF-S 10-22mm, at the 10mm setting, the elementprotrudes too far back toward EF mount camera bodies.The 10D, D60, and earlier cameras share the EF-onlymount with the full frame EOS camera bodies, and alsowith the APS-H size EOS camera bodies (1D series priorto the 1D X), despite having a smaller sensor and there-fore a smaller mirror.

2 List of EF-S lenses

See also: List of EF lenses

The EF-S lens mount is a relatively new offering fromCanon, so the selection of available lenses is limited com-pared to the full EF range, but it is backward compatiblewith the EF mount, and can therefore still accept all EFlenses. As of September 2014, no EF-S lens has beenproduced with the “L” designation or with Diffractive op-tics, and only two EF-S prime lenses have been produced.

3 References[1] “Technical Hall - Technical report 2004.1”. Canon.com.

Retrieved 2013-06-10.

[2] “Canon EF-S 17-55mm f/2.8 IS USM Lens Review”.The-digital-picture.com. Retrieved 2013-06-10.

4 External links• Canon Camera Museum

EF lens (left) and EF-S lens (right). Note raised ring on EF-Slens.

• EF Lens Lineup at Canon USA

• EF/EF-S lens chart

• EF-S lenses compatible with a 10D

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5.1 Text• Canon EF-S lens mount Source: http://en.wikipedia.org/wiki/Canon_EF-S_lens_mount?oldid=626660453 Contributors: Heron, Egil,JidGom, Traal, Dale Arnett, Reub2000, Jason Quinn, Christopherlin, DaveJB, Mouser, Slivester, Cynical, Rich Farmbrough, Phule, Mvd-hout, Cyron, Johnteslade, Courtarro, Keenan Pepper, Ashley Pomeroy, Hu, Cburnett, Gene Nygaard, Stuartyeates, Kenliu, Mindmatrix,Hbdragon88, Magister Mathematicae, Lauri Kosonen, Reisio, GreyCat, Tedder, WikiWikiPhil, Jmorgan, Digitalme, Sukitrebek, Diliff,Splette, Hellbus, Ragesoss, Brandon, Brian Crawford, Voidxor, Zwobot, Shotgunlee, Kakero, RamirBorja, SmackBot, ElectricRay, Slo-man, Bluebot, Jkruis, Wuffyz, Hateless, Dodgens, Thijs!bot, Klausness, SNx, Bernopedia, Atorero, GermanX, I B Wright, Thegreenj,Silphage, Gonzalo M. Garcia, Avijaikumar, VolkovBot, V Gabor, Der Wolf im Wald, DragonLord, Matthewchj, SieBot, NJJ.Rocher,ClueBot, Nebrot, Sun Creator, SchreiberBike, Jovianeye, SilvonenBot, Addbot, Pachard, Luckas-bot, Yobot, Rubinbot, ArthurBot, Ober-sachsebot, SCΛRECROW, Locobot, Chaheel Riens, FrescoBot, Avidiax, LucienBOT, YvesRenard, Joaotaveira, Necror, Ripchip Bot,Steroid Maximus, AvicBot, Rangoon11, Reatlas, GodeNehler and Anonymous: 64

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