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

      Photo Review 8.9

      In summary

      The RF-S 18-45mm f/4.5-6.3 IS STM is a surprisingly good performer for a kit lens, and represents very good value for money. Its main weaknesses are its 2.5x zoom range and limited wide-angle coverage. Build quality is decent for a mostly plastic lens.

      Full review

      The RF-S 18-45mm f/4.5-6.3 IS STM is one of two kit lenses announced in late May, along with the EOS R7 and R10 cameras and designed for the cropped-sensor format. Compact and light in weight, it features a retractable design and, while not particularly fast is a decent ‘take everywhere’ lens and represents good value for money when purchased with a camera body. Integrated optical stabilisation claims up to 6.5 stops of camera shake correction, a useful feature with the unstabilised EOS R10.

      Angled view of the RF-S 18-45mm f/4.5-6.3 IS STM lens without its end caps. (Source: Canon.)

      The zoom range is equivalent to 29-72mm in 35mm, which is quite modest at both the wide and the telephoto ends. Also modest is the optical design, which contains 7 elements in 7 groups and includes two PMo (Precision Moulded optics) aspherical elements. Canon’s Super Spectra Coating minimises ghosting and flare. No lens hood is supplied but the EW-53 hood is available as an option for between AU$20 and $33, depending on where you buy it.

      Like the RF-S 18-150mm f/3.5-6.3 IS STM, this lens employs a lead-screw-type stepping motor for focusing. It’s fast and almost silent, allowing the lens to be used for shooting video. We reviewed the lens on the EOS R10 camera, which is reviewed separately.

      Who’s it For?
      This lens is really only suitable for use with the EOS R7 or EOS R10 cameras and any future cropped-sensor EOS models Canon releases. It’s worth bundling it with a camera if you buy either model since you’ll get a $569 lens for $150 – which could be seen as a bargain. We’d recommend adding the lens hood to the bundle, particularly if you can negotiate a competitive price.

      Like the RF-S 18-150mm f/3.5-6.3 IS STM, the RF-S 18-45mm f/4.5-6.3 IS STM has a variable aperture that changes quickly as the lens is zoomed in. Maximum and minimum apertures at the main focal length settings are shown in the table below.

      Focal length Maximum aperture Minimum aperture
      18mm f/4.5 f/22
      24mm f/5.0 f/25
      28mm f/5.0 f/29
      35mm f/5.6 f/29
      45mm f/6.3 f/32

      However, it’s not really worth stopping down beyond f/11 at any focal length due to the effects of diffraction.

      Build and Ergonomics
      The small size and light weight of this lens suggest it’s made mostly from plastic, with a plastic mounting plate. Like the RF-S 18-150mm f/3.5-6.3 IS STM, this lens is made in Taiwan.

      The front element of the lens is approximately 15 mm in diameter. It bulges outwards   from its recessed location inside a 23 mm diameter partially-ribbed black plastic ring with a raised edge that carries the threading for 49 mm screw-in filters. The bayonet fitting for the lens hood is on the outer edge of this section of the inner barrel.

      Two side views of the RF-S 18-45mm f/4.5-6.3 IS STM lens showing the change in length when the inner barrel is extended to the 18mm position. (Source: Canon.)

      Because the lens retracts (as shown above), you have to zoom the inner barrel out to the 18mm position before any photos can be taken. You’ll encounter a slight resistance during this process, which adds about 28 mm to the overall length of the lens, which is greatest at the 18mm position.

      Zooming the lens from 18mm to 45mm pulls the inner barrel back by approximately 5 mm mid-way between the 35mm and 45mm focal length marks.  The inner barrel doesn’t rotate during zooming facilitating the use of the lens with angle-critical filters.

      The 7 mm wide control ring is located at the leading edge of the outer barrel, where it does double duty as a manual focusing ring. It has a hatched surface to provide a secure grip. Switching between the focus and control modes is done via the camera’s menu since there are no dedicated controls on the lens barrel.

      The zoom ring is located just behind the control ring. It is 17 mm wide with a 10 mm wide band of moulded ribbing around its middle. The trailing edge of the zoom ring is stamped with markings for the 18mm, 24mm, 28mm, 35mm and 45mm focal length settings. These line up against an index mark located just in front of the Canon branding on the fixed, 11 mm wide section of the barrel, which flares gently out to become the lens mount.

      A grey, faux metal band runs around the mount at this junction, carrying the red index mark for attaching the lens to a camera body. The mount itself is made from plastic.


      Our Imatest tests showed the review lens to be a surprisingly good performer for a fairly basic kit lens. The best measured performance was at the 35mm focal length with an aperture of f/5.6, although resolution for JPEG files comfortably exceeded expectations in the centre of the frame at similar apertures at the 18mm, 24mm and 28mm focal lengths.

      Resolution was significantly higher for CR3.RAW files, which also recorded a noticeably wider dynamic range. This difference was measurable across the aperture and focal length ranges of the lens.

      We found resolution dropped a little at 45mm and edge softening could be seen at all focal length settings, as shown in the graph below. A further decline occurred at longer focal lengths with a sharp drop from about f/8 on due to diffraction.

      Lateral chromatic aberration is corrected by default in Canon’s cameras so it’s no surprise to find it remained well down in the negligible band for all focal length settings with JPEG files, as shown in the graph of our test results below. The red line marks the boundary between negligible and low CA.

      A check of CR3.RAW files recorded simultaneously and converted into TIFF format with all optical corrections disabled in the Adobe Camera Raw showed chromatic aberration to be higher than we measured for JPEGs, which was anticipated. However, it never ventured into the ‘low’ band.

      Without a lens hood it was easy to force the lens to flare, resulting in both veiling and flare artefacts. Interestingly, we also found a lot of colour effects in sunstars when we examined the raw files from the camera, which appeared nice and sharp. As expected, they weren’t visible in the JPEG files where they seemed rather muddy-looking as a result of automatic corrections.

      Sunstars were nice and sharp at both ends of the focal length range. Bokeh was much as expected from an extended-range kit lens; acceptable but not inspiring. Readers should note some of the test shots were captured in overcast conditions, which made it difficult to push this aspect of the lens performance.

      Autofocusing was generally fast and accurate, provided the appropriate focus mode and focus area were selected. We had few problems with getting sharp pictures, even with moving subjects, although when we left selection to the camera, there were a few times when the focus landed on the wrong part of the frame. An example is provided in the Samples section below.

      With all in-camera optical corrections disabled, there was slight vignetting at the widest apertures across all focal lengths, which became a little more obvious at 45mm, where the maximum aperture is f/6.3. Enabling the optical corrections eliminated most vignetting and the problem is easily corrected when raw files are converted into editable formats.

      Rectilinear distortion had to be assessed through CR3.RAW files with all optical and profile corrections disabled in Adobe Camera Raw. We found noticeable barrel distortion at the 18mm but it gradually reduced to barely visible at 28mm.

      No distortion was evident at 35mm and only barely visible pincushion distortion at 45mm. Both vignetting and rectilinear distortions are largely irrelevant since they are corrected automatically in JPEGs and most raw file converters.


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      Picture angle: 64 degrees30 minutes to 28 degrees 20 minutes
      Minimum aperture:  f/22-32
      Lens construction: 7 elements in 7 groups (including 2 PMo aspherical elements), Super Spectra coating
      Lens mounts: Canon RF-S
      Diaphragm Blades: 7 (rounded aperture)
      Weather resistance: Not specified
      Focus drive: Stepping motor
      Stabilisation: Yes (up to 4 stops; 6.5 stops with coordinated IS control)
      Minimum focus: 14-25 cm at 18mm; 16-26 cm at 45mm
      Maximum magnification: 0.16x
      Filter size: 49 mm
      Dimensions (Diameter x L): 44.5 x 69.0 mm
      Weight: 130 grams
      Standard Accessories: Front and end caps
      Distributor: Canon Australia; 1800 021 167



      Based on JPEG files recorded with the EOS R10 camera.

      Based on CR3.RAW files recorded simultaneously and converted into 16-bit TIFF format with Adobe Camera Raw.



      Vignetting at 18mm f/3.5.

      Vignetting at 24mm f/4.0.

      Vignetting at 28mm f/5.0.

      Vignetting at 35mm f/5.6.

      Vignetting at 45mm f/6.3.

      Rectilinear distortion at 18mm.

      Rectilinear distortion at 24mm.

      Rectilinear distortion at 28mm.

      Rectilinear distortion at 35mm.

      Rectilinear distortion at 45mm.

      18mm focal length, ISO 100, 1/250 second at f/8.

      45mm focal length, ISO 100, 1/125 second at f/8.

      45mm focal length, ISO 100, 1/200 second at f/10.

      Close-up with the Scene preset; 18mm focal length, ISO 100, 1/250 second at f/7.1.

      Close-up in Av mode at 45mm focal length, ISO 100, 1/250 second at f/6.3.

      Bokeh in evenly-lit close-up; 31mm focal length, ISO 250, 1/80 second at f/5.6.

      Bokeh in brightly-lit close-up; 45mm focal length, ISO 100, 1/500 second at f/6.3.

      22mm focal length, ISO 160, 1/5 second at f/20.

      Backlighting: 20mm focal length, ISO 100, 1/200 second at f/8.

      Sunstar at f/22 with 18mm focal length; ISO 200, 1/160 second.

      Sunstar at f/32 with 45mm focal length; ISO 100, 1/30 second.

      32mm focal length, ISO 100, 1/85 second at f/7.1.

      32mm focal length, ISO 100, 1/60 second at f/7.1.

      45mm focal length, ISO 320, 1/60 second at f/6.3.

      45mm focal length, ISO 500, 1/80 second at f/7.1.

      18mm focal length, ISO 100, 1/125 second at f/6.3.

      45mm focal length; ISO 100, 1/13 second at f/20.

      45mm focal length, ISO 100, 1/320 second at f/8.

      Additional image samples can be found with our review of the Canon EOS R10 camera.



      RRP: AU$569

      • Build: 8.6
      • Handling: 8.6
      • Image quality: 9.0
      • Autofocusing: 9.0
      • Versatility: 8.5