Canon ef lenses have been around since the film slr days.
Ef s lenses on full frame.
Canon have done this to prevent you from using an ef s lens on a full frame camera body and forcing it will very likely damage the mount resulting in a hefty repair bill.
The first is mechanical.
Using ef s lens on full frame canon bodies.
This article covers canon ef full frame lenses but there is another world of ef s or aps c lenses for the company s entry level and mid range dslrs.
Essentially there are two reasons why ef s lenses won t work on a full frame body.
Ef s lenses manufactured by canon have an extra tab that prevents them from being mounted on full frame and aps h canon bodies.
They were designed to cover a 35mm film frame.
In short ef s lenses are not compatible on full frame cameras.
To start most native canon ef s lenses will not physically mount on canon full frame cameras.
Many digital lenses made by third party manufacturers do not.
You should be careful when using them on full frame bodies because the full frame mirror passes much closer to the lens mount flange than the mirror on crop bodies does.
As you know ef s lenses are designed for use on aps c crop sensor cameras so you wouldn t normally be able to use them on full frame dslrs.