Canon EF 24-70mm f/4L IS USM Lens


    Photo Review 8.8
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    Canon EF 24-70mm f/4L IS USM Lens

      In summary

      The compact size and relatively light weight of Canon's EF 24-70mm f/4L IS USM lens make it an attractive option for wedding photographers and those who cover social events. It could also be handy for landscape photography when used with Canon's 'full frame' camera bodies.

      As a general-purpose standard zoom lens, the 24-70mm focal length range is a bit limited. However, this lens could be nicely paired with a 70-200mm or 70-300mm tele-zoom lens to make the foundation of a kit for a 'full frame' camera body.

      Able to produce sharp images throughout its zoom range, it offers a couple of useful features that will attract serious photographers looking for more versatility than some competing lenses provide.

      Built-in stabilisation is a genuine bonus and the macro function, though it has limitations, could be a key feature for some potential purchasers. Most users will be able to cope with the relatively low levels of distortion for this type of lens and bokeh, while not without slight flaws at normal focal lengths, can be quite nice in macro shots.

      Buy this lens if:
       - You require a professional-quality standard zoom lens for a 'full-frame' DSLR.
       - You want effective built-in stabilisation.
       - You want superior performance across a wide range of aperture settings with all focal lengths.
       - You would like macro capabilities.

      Full review

      Announced towards the end of 2012, Canon's EF 24-70mm f/4L IS USM zoom lens provides a lighter, more affordable alternative to the EF 24-70mm f/2.8L USM, which we reviewed in April of the same year. The latest version of the f/2.8 lens is priced $950 higher than the f/4 lens in Australia (or $800 higher in the USA). Both lenses both allow you to shoot with their maximum aperture at all focal length settings.
       

      The Canon EF 24-70mm f/4L IS USMzoom lens. (Source: Canon.)

      Although the 24-70mm f/4L lens is optimised for 'full frame' DSLRs, it can also be used with Canon's EOS cameras with smaller (APS-C) sensors. The 1.6x crop factor provides an effective focal length range equivalent to 38.4-112mm.

      While it's a stop slower than its sibling, the f/4 lens has a couple of significant advantages. It's roughly 200 grams lighter and stabilised, with a claimed compensation of up to four f-stops for normal shooting. In addition, it includes a special 'macro' setting that will focus down to a couple of centimetres, where the stabilisation system provides 2.5 f-stops of shake correction.

      Both lenses have ultrasonic focusing motors with FTM (full-time manual focusing) over-ride.  The nine-bladed iris diaphragms in both lenses close to circular apertures and both lenses are built to resist dust and moisture – although they're not classified as 'waterproof'.

      The optical design of the EF 24-70mm f/4L IS USM comprises 15 elements in 12 groups and includes two aspherical elements plus two Ultra-low Dispersion (UD) lenses. Super Spectra Coatings have been applied to minimise chromatic aberration, colour blurring and flare.

      According to the box the review lens came in, this lens should be supplied with the new Mark II front and end caps plus the EW-83L lens hood and LP1219  soft case. Only the lens caps were supplied with the review lens but buyers can expect the hood and case to be included. The hood will add roughly 35 mm to the overall length of the lens.

      Build and Ergonomics
      The build quality of the review lens was as good as other Canon L-series lenses we've reviewed and meets professional standards in virtually all respects. Constructed on a metal foundation, it features a solid, chromed mounting plate and high-quality polycarbonate cladding.

      All components are tightly assembled to inhibit entry of moisture and dust and even when the inner barrel is extended, there appears to be no gap so it should be usable in most outdoor situations. The front element does not rotate during focusing or zooming, allowing use of angle-critical attachments like polarisers.

      The focusing ring is 17 mm wide and located approximately 20 mm back from the front of the lens. It carries a 12 mm wide, ridged rubber grip band and turns through about 50 degrees between two 'soft stops' that mark the ends of the focusing range.

      Behind the focusing ring is a distance scale, marked in metres and feet. To the left of this scale are the standard AF/MF and stabiliser on/off slider switches.

      Around the barrel on the right hand side of the distance scale is a new Macro/Lock slider that engages close focusing for a maximum magnification of 0.7x. You have to push the slider forward, hold it in position and turn the zoom ring to engage this 'macro' mode.

      To lock the lens, you set it to 24mm and pull the slider back towards the camera. The review lens showed no tendency to creep when carried facing downwards so we feel you can safely leave the slider between the Lock and Macro positions most of the time.

      Obtaining the maximum magnification in macro mode requires you to shoot with the front element of the lens only a centimetre or so away from the subject. This makes it impossible to use flash (even ring lights could be problematic) and you run the risk of shading the subject in ambient lighting, particularly if you fit the lens hood.

      Nevertheless, this mode can be handy  for close-ups when you don't want to carry a dedicated macro lens. It also delivers surprisingly good results when used correctly.

      Behind the distance scale is the zoom ring, which is 18 mm wide and carries a thickly-ridged rubber grip band. The trailing edge of this ring is stamped with four focal length settings, denoting the 24, 35, 50 and 70mm focal lengths. The inner barrel extends by approximately 32 mm when you zoom in from 24mm to 70mm.

      Zooming is very smooth and controllable, thanks to the wide zoom ring. Small adjustments even can be made with one finger, although the natural operating position requires finger and thumb for fast zooming.

      Performance
       The review lens turned in a sterling performance on the Canon EOS 6D body we used for our tests, which was a good match for this lens. As expected for a Canon USM lens, we found autofocusing to be fast, quiet and accurate when the viewfinder was used but slower when the camera was used in live view mode.

      AF lag was most noticeable when recording movie clips, which is to be expected with contrast-based systems. However, delays weren't so long as to compromise the quality of movie recordings, particularly if zooming and panning were relatively slow.

      We also found focus could shift slightly during zooming when shooting stills. But manual correction in AF mode was easy, thanks to the FTM capability of the lens.

      The image stabilisation system worked as well as expected. Canon's technology is mature so it was no surprise that the claimed four-f-stop advantage proved very credible, as did the 2.5-stop advantage in the macro mode. We were even able to push the limits under optimal conditions and obtain more than 50% of shots with acceptable sharpness. Examples are provided below.

      Imatest showed the lens to be capable of matching the performance of the 6D's sensor with its best performance being around f/5.6 at the 24mm, 35mm and 70mm focal lengths. Slightly lower resolution was recorded at 50mm across all focal length settings up to about f/11, when diffraction reduced resolution across the board.

      Edge softening was detectable at all focal lengths up to about f/5.6, although it became less evident as the lens was stopped down. The central areas in images remained quite sharp, even when stopped down beyond the diffraction limit. The graph below shows the results of our tests.

      Lateral chromatic aberration was consistently negligible at almost all focal length and aperture settings. In the graph of our Imatest results below, the red line marks the boundary between 'negligible' and 'low' CA, while the green line separates 'low' from 'moderate' CA.

       

      Vignetting was relatively low  at the widest aperture settings, but quite noticeable with the 24mm focal length. By 70mm some corner darkening could be seen but it was never enough to impact seriously on image quality. Stopping down to f/5.6 made it disappear at all focal lengths. Most Canon cameras provide peripheral illumination correction to deal with this problem and it is also easily corrected in editing software.

      Distortion was very low for the longer focal lengths, although barrel distortion was evident at 24mm. Between 35mm and 50mm, no significant distortion could be seen. Slight pincushioning was visible at 70mm. These aberrations can be corrected with editing software.

      Without the lens hood, the review lens was slightly flare prone in backlit situations, particularly at wider angles of view. However, this was not as bad as we had expected and overall flare performance can be rated as very good.

      Bokeh varied with focal length, aperture setting and subject distance. In most cases it was fairly smooth and attractive and out-of-focus highlights remained circular in shape. We obtained some attractive background blurring in close-ups taken with the macro mode, particularly at wide apertures.

      Conclusion
      The compact size and relatively light weight of Canon's EF 24-70mm f/4L IS USM lens make it an attractive option for wedding photographers and those who cover social events. It could also be handy for landscape photography when used with Canon's 'full frame' camera bodies.

      As a general-purpose standard zoom lens, the 24-70mm focal length range is a bit limited. However, this lens could be nicely paired with a 70-200mm or 70-300mm tele-zoom lens to make the foundation of a kit for a 'full frame' camera body.

      Although relatively pricey, we found this lens to be a very good performer in a very competitive lens category. Able to produce sharp images throughout its zoom range, it offers a couple of useful features that will attract serious photographers looking for more versatility than some competing lenses provide.

      Built-in stabilisation is a genuine bonus and the macro function, though it has limitations, could be a key feature for some potential purchasers. Most users will be able to cope with the relatively low levels of distortion for this type of lens and bokeh, while not without slight flaws at normal focal lengths, can be quite nice in macro shots.

      Buy this lens if:
       - You require a professional-quality standard zoom lens for a 'full-frame' DSLR.
       - You want effective built-in stabilisation.
       - You want superior performance across a wide range of aperture settings with all focal lengths.
       - You would like macro capabilities.

       SPECS

       Picture angle: 46 degrees 40 minutes
       Minimum aperture: f/16
       Lens construction: 15 elements in 12 groups (including 2 aspherical and 2 UD elements)
       Lens mounts: Canon EF
       Diaphragm Blades: 9 (circular aperture)
       Focus drive: Ultrasonic with FTM
       Stabilisation: Yes,  4 f-stops, 2.5 f-stops in macro mode
       Minimum focus: 20 cm in normal range; 1.5 cm in macro mode
       Maximum magnification: 1:1.4
       Filter size:  77 mm
       Dimensions (Diameter x L): 83.4 x 93 mm
       Weight: Approx. 600 grams

      TESTS

      (based on JPEG files from the Canon EOS 6D)

       

       

      SAMPLES

      Vignetting at 24mm.
       
       

      Vignetting at 50mm.
       
       

      Vignetting at 70mm.
       
       

      Rectilinear distortion at 24mm.
       
       

      Rectilinear distortion at 50mm.
       
       

      Rectilinear distortion at 70mm.
       
       

      24mm focal length; ISO 100, 1/60 second at f/14.
       
       

      28mm focal length; ISO 100, 1/100 second at f/14.
       
       

      Strong backlighting at 24mm focal length; ISO 100, 1/200 second at f/10.
       
       

      Strong backlighting at 70mm focal length; ISO 100, 1/200 second at f/7.1.
       
       

      Stabilisation test: 1/4 second at f/4, 70mm focal length; ISO 3200.
       
       

      Stabilisation test in Macro mode: 1/10 second at f/4.5, 70mm focal length; ISO 4000.
       
       

      70mm focal length; ISO 100, 1/125 second at f/5.
       
       

      Close-up in normal zoom range at 70mm, f/4; ISO 100, 1/60 second.
       
       

      Close-up in normal zoom range at 70mm, f/5.6; ISO 250, 1/80 second at f/5.6.
       
       

      Macro mode; 70mm focal length, ISO 125, 1/80 second at f/4.
       
       

      Macro mode; 70mm focal length,  ISO 320, 1/60 second at f/5.6.
       

      Macro mode; 70mm focal length,  ISO 500, 1/80 second at f/8.

      Macro mode; 70mm focal length,  ISO 1600, 1/60 second at f/8.
       
       

      Macro mode; 70mm focal length, ISO 640, 1/80 second at f/4.
       

      Rating

      RRP: n/a; ASP: AU$1949; US$1499 (MSRP)

      • Build: 9.0
      • Handling: 8.8
      • Image quality: 8.8
      • Versatility: 8.8

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