Canon RF-S 18-45mm f/4.5-6.3 IS STM review

The Canon RF-S 18-45mm f/4.5-6.3 IS STM is born of necessity. The release of two new APS-C Canon cameras means the release of two new APS-C Canon kit lenses – but is this compact zoom worth picking up on its own merits?

While the Canon RF-S 18-45mm f/4.5-6.3 IS STM is designed to be used with the Canon EOS R10 and Canon EOS R7 (and, primarily, the former as it's much cheaper and lighter), it uses the same RF mount as full frame cameras like the Canon EOS RP and Canon EOS R6 – though these bodies will automatically switch to a cropped APS-C shooting mode. 

So, even if this optic doesn't crack the list of best Canon RF lenses, does it pack enough features to make it a compelling addition to your kit bag – or a worthy bundle with a brand new R7 or R10? Let's take a look…

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Canon RF-S 18-45mm f/4.5-6.3 IS STM: Specifications

Mount: Canon RF
Full-frame: No (APS-C)
Autofocus: Yes
Stabilization: Yes (4 stops / 6.5 with IBIS)
Lens construction: 7 elements in 7 groups
Angle of view (H, V, D): 64° 30'- 28° 20', 45° 30' - 19° 05', 74° 20'- 33° 40'
Diaphragm blades: 7
Minimum aperture: f/22 at 18mm • f/32 at 45mm
Minimum focusing distance: 0.2 (18mm) (Manual Focus: 0.15) • 0.3 (35mm) (Manual Focus: 0.24) • 0.35 (45mm) (Manual Focus: 0.25)
Maximum magnification ratio: 0.14x (18mm) (Manual Focus: 0.25x) • 0.15x (35mm) (Manual Focus: 0.21x) • 0.16x (45mm) (Manual Focus: 0.26)
Filter size: 49mm
Dimensions: 44 x 62mm
Weight: 124g

Canon RF-S 18-45mm f/4.5-6.3 IS STM: Key features

Thanks to the 1.6x crop factor of Canon's APS-C format, the 18-45mm has a full frame equivalent field of view of 29-72mm, giving it a short but versatile focal range (slightly shorter than that of the usual 18-55 / 29-88mm kit lenses).

While its sister kit lens, the Canon RF-S 18-150mm f/3.5-6.3 IS STM, has a much longer focal length, the benefit here is its compact size and weight. The 18-45mm measures just 44 x 62mm and weighs virtually nothing at a paltry 124g.

It also boasts optical image stabilization to the tune of 4 stops of compensation on a body without in-body image stabilization, which goes all the way up to 6.5 stops when mounted on a body with stabilization. 

While the lens retails (in some territories) on its own for around 300 bucks, in a kit with the R10 it only adds about 100 to the price – making it a very compelling option to pick up with a new body.

Canon RF-S 18-45mm f/4.5-6.3 IS STM: Build and handling

The first thing you'll notice about this optic is its almost pancake lens compactness. The second thing you'll notice is that it doesn't actually shoot this way; you need to twist the lens and activate the telescoping mechanism in order to start shooting, which about doubles the length.

As noted, the lens is tiny and weighs virtually nothing, so the fact that it packs image stabilization is very impressive. However, the (understandable) compromise is that there is no weather sealing here.

The 18-45mm features a very discreet manual focusing ring, which doubles as a customizable Control Ring as is standard on Canon's RF-mount lenses (enabling you to adjust exposure values such as ISO, compensation and so on). 

The larger zoom ring sits beneath it and offers snappy, pleasing control with a short throw. On the nose of the lens is a 49mm filter thread, though as you'd imagine there is no provision to attach a lens hood.

Canon RF-S 18-45mm f/4.5-6.3 IS STM: Performance

We were able to get some sharp images with real bite and detail – and not just in "acceptable for a kit lens" terms, either. Certainly there's a world of difference between this and, say, the Canon RF 15-35mm f/2.8L, but then there's a world of difference in the price, size and weight, too. 

The RF-S 18-45mm is designed to be the leanest, lightest lens possible for the EOS R7 and R10, while offering good-to-great image quality for both stills and video – and it achieves those goals admirably.

Obviously this is a slower lens, at f/4.5-6.3, so you're going to need to crank your ISO or slow your shutter to work in challenging light – but when doing the latter, the brilliant stabilization (made brilliant-er with a stabilized body) makes a huge difference.

The STM focusing mechanism is smooth and near-silent, making it great for video as well as stills, and it works impressively with the cutting-edge autofocus systems of the R7 and R10. 

Even when shooting ice skaters in a very murky indoor location, the AF was able to keep up with eyes and faces even when they were moving unpredictably and appearing very small in the frame. 

Canon RF-S 18-45mm f/4.5-6.3 IS STM: Lab results

We run a range of lab tests under controlled conditions, using the Imatest Master testing suite. Photos of test charts are taken across the range of apertures and zooms (where available), then analyzed for sharpness, distortion and chromatic aberrations.

We use Imatest SFR (spatial frequency response) charts and analysis software to plot lens resolution at the center of the image frame, corners and mid-point distances, across the range of aperture settings and, with zoom lenses, at four different focal lengths. The tests also measure distortion and color fringing (chromatic aberration).

Important note: we're testing a pre-production sample of the RF-S 18-45mm, although we've got no reason to expect retail samples to differ considerably in performance.

Sharpness:

Center sharpness is excellent at all focal lengths and apertures. Corner sharpness, however, is much less impressive, and remains so throughout the focal range, regardless of aperture.

Fringing:

With in-camera aberration correction disabled, the 18-45mm generates considerable fringing, which is especially noticeable at 45mm.

Distortion:

Here's another example of how some modern lenses are increasingly reliant on in-camera corrections to compensate for fringing, and in this case, optical distortion. With distortion correction disabled, the RF-S 18-45mm generates huge barrel distortion at 18mm. You'll have to zoom in to 35mm to get an undistorted image.

Canon RF-S 18-45mm f/4.5-6.3 IS STM: Verdict

As a compact companion to the Canon EOS R7 or R10, the RF-S 18-45mm is a fantastic option for everyday stills and video shooting. It's obviously not going to give the same performance as L-series or even mid-rage glass, but it still delivers solid image quality (providing you leave in-camera optical corrections firmly enabled!), along with with fast autofocus and solid stabilization. 

If you own a full frame EOS R camera then there's really no need to look at this optic. If you're buying one of the new APS-C bodies, though, adding this lens to your bundle is an absolute no-brainer.

Canon RF-S 18-45mm f/4.5-6.3 IS STM: Sample images

Read more: 

Hands on: Canon EOS R10 review
Hands on: Canon EOS R7 review
Best Canon cameras
Best Canon RF lenses