Canon EF vs. EF-S Lenses: Differences and Compatibility

EF lenses fit all Canon EOS DSLRs, including full frame. EF-S lenses are made only for EOS DSLRs with an APS-C sensor and cannot be used on full-frame DSLRs^[1]. The difference lies in the smaller image circle and the shorter back focus of EF-S lenses^[2]. On mirrorless EOS R and EOS M cameras, both types work through an adapter.

EF and EF-S: image circle and back focus

Canon's EF-S lenses are tailored optically and mechanically to APS-C sensors. Two things contribute to this^[2]:

• Smaller image circle: It is sized for the APS-C sensor. The lens covers only that smaller area.
• Shorter back focus: The distance between the rear lens element and the sensor is shorter than on regular EF lenses. It suits the smaller quick-return mirror of APS-C cameras.

EF lenses, in contrast, cover a full-frame sensor. That is why they work on both full frame and APS-C.

Because of the short back focus, EF-S lenses cannot be mounted mechanically on cameras that do not support them. A rubber ring on the rear end also protects the camera body if someone tries anyway^[2]. Canon warns that attaching one to an incompatible camera may damage the body or the lens^[1].

How to tell lens and mount apart

The mount on the camera shows what it accepts^[3]:

• Red dot and white square: EOS APS-C DSLR, accepts EF and EF-S.
• Red dot only: EOS full-frame DSLR, accepts EF only.
• Red line: EOS R System, mirrorless (RF mount).
• White dot: EOS M series, mirrorless (EF-M mount).

You align EF-S lenses with the white square mark and EF lenses with the red one^[2]. The type is also in the name, for example "EF-S 24mm f/2.8 STM".

Which lens fits which camera?

Canon shows the compatibility in a chart, summarized here^[3]:

Lens	APS-C DSLR	Full-frame DSLR	EOS R APS-C	EOS R full frame	EOS M
EF	yes, crop 1.6	yes	with adapter, crop 1.6	with adapter	with adapter, crop 1.6
EF-S	yes	no	with adapter	with adapter, crop	with adapter
EF-M	no	no	no	no	yes
RF	no	no	yes, crop 1.6	yes	no
RF-S	no	no	yes	yes, automatic crop	no

Canon names the Mount Adapter EF-EOS R for the EOS R cameras and the Mount Adapter EF-EOS M for the EOS M series^[3].

EF-S lenses on full frame

On DSLRs it does not work. The EOS 5D, 6D, 1D X and the other full-frame and 1D models are listed by Canon as not compatible. The same goes for very old APS-C models such as the EOS 10D, D60 and D30^[1]. If you move from APS-C to a full-frame DSLR, you need EF lenses.

On full-frame EOS R cameras it works with the adapter. Canon lists EF-S there as compatible with the EF-EOS R adapter and points to possible limitations described in the camera's manual^[3]. You get cropped images that match the smaller image circle of EF-S optics^[4]. Fewer pixels also means less resolution for large enlargements^[5]. The same principle applies at Sony, as the article APS-C lenses on full-frame Sony cameras shows.

EF lenses on APS-C cameras

This works on all APS-C models, only the focal length acts longer. Canon uses a crop factor of 1.6: a 50 mm lens equals about 80 mm in 35 mm terms on APS-C^[2]. What the crop factor does otherwise is covered in the article APS-C vs. full frame. EF lenses are built for the larger sensor and are often larger than EF-S lenses^[5]. In the catalog you find Canon EF, split into APS-C and full frame.

EF-M and RF-S: do not confuse them with EF-S

• EF-M is the mount of the EOS M series and works only there. EF-M lenses fit neither DSLRs nor EOS R cameras^[3]. More on the Canon EF-M page.
• RF-S is the APS-C variant of the RF mount and works on all EOS R cameras. On full-frame models, the camera automatically crops to APS-C^[5]. The page Canon RF APS-C lists the lenses.
• EF-S on the EOS M series works with the EF-EOS M adapter: attach the lens to the adapter first, then the adapter to the camera^[1].

Lenses from other makers

On lenses from other makers the format is in the name, for example "DC" for APS-C and "DG" for full frame at Sigma. Sigma writes that an APS-C lens on a full-frame camera vignettes heavily without a crop mode^[6]. Whether such a lens with an EF mount is usable on your full-frame camera therefore depends on the camera and the manufacturer's notes. Check the maker's compatibility list for your body before buying.

Frequently asked questions

Can you use an EF-S lens on a full-frame camera?

Not on Canon full-frame DSLRs. With the EF-EOS R adapter it works on full-frame models of the EOS R series, and the camera then crops to APS-C^[3][4].

Can you use EF lenses on APS-C cameras?

Yes. On EOS DSLRs with an APS-C sensor, all EF lenses fit, and the focal length acts longer because of the factor 1.6^[2].

What is the difference between EF-S and EF-M?

EF-S is for APS-C DSLRs, EF-M for the mirrorless EOS M cameras. The mounts are not interchangeable, and EF-S works on EOS M only with an adapter^[3].

Do EF lenses fit the EOS R?

Yes, with the Mount Adapter EF-EOS R^[3]. On APS-C models of the EOS R series, the crop factor of 1.6 applies.

How can you recognize an EF-S lens?

By the name "EF-S", by the white square mark on the mount and by the rubber ring on the rear end^[2].