Robertven Loc: Fort Worth

What is the difference between EF & EFS lenses?

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

EF lenses are for any EOS SLR/DSLR

EF-S lenses are only for APS-C (crop sensor) cameras.

Robertven Loc: Fort Worth

Thanks! That is simple enough.

robertjerl Loc: Corona, California

EF mount lenses are designed for full frame cameras, but will work on crop sensor cameras. The sensor only sees the center part of the image so you get the field of view of a longer lens. So a 100mm EF lens on a crop sensor will give an image like a 160mm EF lens on a FF camera.

EF-S mount lenses are designed for crop sensor cameras and will not fit on a full frame body due to a deliberate mount difference done by Canon to protect lens elements and the mirror. Third party EF-S lenses just use the EF mount and will mount on FF bodies but will vignette the image. They build them so the lens element vs mirror confilict/damage doesn't happen.

Canon's high end L series lenses out perform the EF-S lenses but are heavier and larger so most people only use them when after the highest IQ or because they have both types of body and switch lenses back and forth. The EF-S lenses are smaller, lighter and less expensive. They also have about the same IQ as the non L EF mount lenses.

Of course this stuff only applies to Canon.

flyguy Loc: Las Cruces, New Mexico

This is a very good explanation, in fact about the best I've seen here on the subject.

Architect1776 Loc: In my mind

This is my response as well.

Robertven Loc: Fort Worth

Thanks to everyone who answered. That taught me a lot. :)

revhen Loc: By the beautiful Hudson

All great answers. To add a bit, I think EF-S lenses extend further into the camera so that if they are mounted on a FF camera they would damage the mirror or the lens -- or both! Thus you can mount EF lenses on a smaller sensor camera (T5i, 70D, etc.) but not EF-S lenses on a FF camera.

amfoto1 Loc: San Jose, Calif. USA

In some cases, yes... the EF-S lens do protrude a bit into the camera and might interfere with the bigger mirror of a full frame camera when focused to particular settings. Mostly this would just be a concern with wide angle lenses that use a "retro focus" design. It's not an issue with other EF-S lenses.

However, the EF-S lens mount itself is a variation of the EF mount that physically prevents the lens from even being attached to a full frame Canon camera. So, it's really a non-issue... unless you modify the EF-S lens trying to make it fit a camera it's not intended for.

revhen Loc: By the beautiful Hudson

See, some people know more than I!

Captryan Loc: Massachusetts

If the sensor only sees the center of the image, does that affect the speed of the lens due to reduce amount of light ?

Architect1776 Loc: In my mind

No

Peterff Loc: O'er The Hills and Far Away, in Themyscira.

Agreed