Canon: Compatibility and differences between EF and EF-S lenses

When it comes to Canon lenses, it's important to understand the differences between EF and EF-S lenses and their compatibility with Canon full-frame and APS-C cameras.

EF lenses are designed for Canon's full-frame cameras and are compatible with both full-frame and APS-C cameras. EF-S lenses are designed specifically for Canon's APS-C cameras and are not compatible with full-frame cameras.

The main difference between EF and EF-S lenses is the size of their image circles. EF lenses are designed to cover the larger image sensor of full-frame cameras, which means they have a larger image circle than EF-S lenses. EF-S lenses, on the other hand, are designed to cover the smaller APS-C image sensor, which means they have a smaller image circle than EF lenses.

When using an EF lens on an APS-C camera, the smaller sensor crops the image, effectively increasing the focal length of the lens. For example, a 50mm EF lens on an APS-C camera will have an effective focal length of around 80mm due to the crop factor. This can be useful for telephoto photography but can be a disadvantage when shooting wide-angle photos.

In contrast, EF-S lenses are designed to work specifically with APS-C cameras, so they don't have the crop factor issue. However, this also means that they are not compatible with full-frame cameras. If you try to use an EF-S lens on a full-frame camera, the lens will vignette or produce a dark circle around the edges of the image due to the smaller image circle.

It's also worth noting that some Canon APS-C cameras, such as the EOS M series, use a different lens mount called EF-M. EF-M lenses are not compatible with Canon's full-frame or APS-C DSLRs, and EF and EF-S lenses cannot be used on EOS M cameras without an adapter.

In summary, EF lenses are compatible with both Canon full-frame and APS-C cameras, while EF-S lenses are only compatible with Canon APS-C cameras. When using EF lenses on an APS-C camera, the smaller sensor will crop the image and effectively increase the focal length of the lens. EF-S lenses are designed specifically for APS-C cameras and do not have the crop factor issue, but are not compatible with full-frame cameras.