Introduction

Ease of Use

Weighing a mere 125g and measuring just 23cm in length, the Canon EF-S 24mm f/2.8 STM is the slimmest and lightest Canon EF-S lens ever produced. Being an EF-S lens, you can only use it on a Canon EOS APS-C body like the 7D Mark II that we tested it with, for a 38mm equivalent angle of view.

The Canon EF-S 24mm f/2.8 STM lens mounted on an EOS 7D Mark II

The Canon EF-S 24mm f/2.8 STM lens mounted on an EOS 7D Mark II

The Canon EF-S 24mm f/2.8 STM lens mounted on an EOS 7D Mark II

As you would expect from such an inexpensive lens, build quality is adequate rather than outstanding. The Canon EF-S 24mm f/2.8 STM feels fairly solid in your hand, despite the all-plastic construction, and the metal mount is very welcome. As you'd expect on such a small lens, the focusing ring is very narrow but has a ridged, rubberised grip band that assists with the finger-tip operation.

Front of the Canon EF-S 24mm f/2.8 STM lens

Front of the Canon EF-S 24mm f/2.8 STM lens

Rear of the Canon EF-S 24mm f/2.8 STM lens

The final control on the lens barrel is a focus mode switch with the usual AF/MF settings. Note that this lens offers full-time manual focusing even when AF is selected.

Front of the Canon EF-S 24mm f/2.8 STM lens

Rear of the Canon EF-S 24mm f/2.8 STM lens

The Canon EF-S 24mm f/2.8 STM lens in-hand

The lens doesn't ship with either a lens hood or a protective bag. It accepts 52mm filters.

Focal Range

At the 24mm focal length the angle of view is 59º 10'.

 Field of view at 24mm

Focusing

The Canon EF-S 24mm f/2.8 STM lens has a very narrow focusing ring that doesn't really encourage you to use it - perhaps Canon thinks that most users of this lens will never manually focus. There are no hard stops at either ends of the range, making it more difficult to set focus at infinity. Manual override of the autofocusing system is available at any time. Polariser users should be pleased that the 52mm filter thread doesn't rotate on focus.

When it comes to auto-focusing, the Canon EF-S 24mm f/2.8 STM zoom is a quick performer, only taking about 0.15 seconds to lock onto the subject when mounted on the Canon EOS 7D Mark II that we tested it with. We didn't experience too much "hunting" though, either in good or bad light, with the lens accurately focusing almost all of the time. It's also a virtually silent performer too, thanks to the built-in STM (Stepping Motor), which makes this lens well-suited to video recording and more candid photography.

Chromatic Aberrations

Chromatic aberrations, typically seen as purple or blue fringes along contrasty edges, are pretty well controlled with this lens, only appearing in a few of our test shots. The examples below show the worst-case scenario.

Light Fall-off

With the lens wide open at f/2.8, you can see some obvious light fall-off in the corners, although Canon's latest APS-C bodies can automatically correct for it when shooting JPEGs. There's also some mild barrel distortion.

Vignetting at 24mm

Macro

The Canon EF-S 24mm f/2.8 STM usefully doubles up as a macro lens, with the close-focus point 16cm/0.52ft from the film/sensor plane, and Canon quotes a maximum reproduction ratio of 0.27x. The following example illustrates how close you can get to the subject, in this case a CompactFlash card.

Close-up performance

Bokeh

Bokeh is a word used for the out-of-focus areas of a photograph, and is usually described in qualitative terms, such as smooth / creamy / harsh etc. The Canon EF-S 24mm f/2.8 STM has an iris diaphragm with 7 rounded blades for a pleasing rendering of the out-of-focus highlights. Below you'll find some examples, but you are also encouraged to check out our sample images.

Sharpness

In order to show you how sharp this lens is, we are providing 100% crops on the following page.