Canon SX720 HS review - biggest ever 40x zoom in a compact

The Canon SX720 HS is a compact camera with a 40x zoom lens, smashing the record of 30x jointly held by Canon, Nikon, Panasonic and Sony. This is great news for people who like to shoot distant subjects but who don’t want to lug a bulky camera around. However, this extra zoom extension is only useful if the camera can produce sharp photos at the full zoom extension. It’s a challenge not just for the lens optics but also for stabilisation and noise handling.

These issues are all the more pressing in a compact-shaped camera. Cramming a 40x zoom into a camera that’s just 38mm thick can’t be easy, or else everyone would be doing it. It remains to be seen whether Canon’s move to 40x is based on technical progress or demands from the marketing department.

Stabilisation is harder, too — or to be more precise, it’s harder to hold a small, slim camera steady. An SLR-shaped camera’s additional size and weight give it some inertia. With a slim compact camera, the slightest movement can make the subject disappear out of shot.

Noise is perhaps the biggest challenge for a compact camera with a big zoom. Zooming in exaggerates camera shake so faster shutter speeds are necessary. Zooming in also shrinks the maximum aperture — in this case from f/3.3 for wide-angle to f/6.9 for telephoto, or a quarter the amount of light. A faster shutter speed and smaller aperture both mean less light hitting the sensor, so the ISO speed must be raised to compensate, and this raises noise levels. Noise is always an issue for cameras with tiny 1/2.3in sensors, and it’s particularly challenging here.

So the SX720 HS has its work cut out if it wants to impress. It makes a good first impression with a smart appearance in a choice of gunmetal grey or dusky red finishes. The layout of buttons is geared more towards point-and-shoot users but it’s good to see an exposure mode dial and a rear wheel for quick adjustment of settings.

There’s not much of a handgrip but the rubber texture and the position of the mode dial means it feels secure in the hand. I found that the optical stabilisation was just as useful when composing shots as when taking them. Tracking moving subjects at the full 960mm (equivalent) zoom position is virtually impossible, so thankfully there’s a button that quickly zooms out to help find the subject. Releasing the button zooms back in again. The same button can be used to make the camera zoom automatically to frame a person’s face, upper body or whole body. I don’t believe there are many people who wouldn’t prefer to use the zoom lever and makes these decisions for themselves, but somebody somewhere might appreciate it.

Big zooms are useful for sports and wildlife photography, but these also require fast performance. The SX720 HS fared reasonably well in this respect, taking around half a second to focus and 0.9 seconds on average between shots. Flash photography was less impressive, taking 8.5 seconds to recharge at full flash power. Continuous mode ran at 6fps until the card was full. Enabling continuous autofocus delivered 2.8fps shooting, but I saw little evidence of it successfully tracking moving subjects.

A bigger frustration are the limited autofocus options. There’s a choice of multi with face detection, centre or tracking, but no option to position the autofocus point anywhere in the frame. Most compact cameras don’t really need this but focus becomes more critical for telephoto shots where there’s a narrow depth of field. I selected the Centre AF mode and regularly had to focus on the subject, reframe it off-centre and then take the shot.

Video quality

Video mode can be a pocket ultra-zoom camera’s secret weapon, as the smaller 2-megapixel resolution of 1080p video is more forgiving of lens sharpness and sensor noise issues. I certainly appreciated the 40x zoom when shooting videos of wildlife at Minsmere RSPB reserve. Video stabilisation worked well, although the results were invariably better when I had something solid to prop my arms against. 

Video quality was good rather than great, with a slight coarseness to details. Shooting in low light resulted in a fair amount of noise but noise reduction kept it under control. It’s disappointing that there’s no option to control the video exposure manually.

Image quality

Photo quality is what really matters for most people, and in the majority of my test shots the SX720 HS punched well above its weight. Colours were vibrant and flattering, although even in bright conditions there was some evidence of noise, particularly in skin tones, and dense foliage and grass lacked clarity. These problems are hard to avoid with a small 1/2.3in sensor.

Focus was pretty good through most of the zoom range but telephoto shots weren’t so impressive, with a distinct haziness to details. I also found that the autofocus in telephoto shots was often slightly off the mark, and sometimes completely off.

Overall exposure levels were expertly judged but the camera sometimes chose odd shutter and ISO speeds. This appears to be down to the camera attempting to raise the shutter speed to avoid motion blur in moving subjects. Sometimes this worked well, but on other occasions it appeared to be confused by camera shake just before taking a picture.

Another issue was that the ISO speed rarely ventured beyond 800, which sometimes meant excessively slow shutter speeds, particularly for telephoto shots. Raising the ISO speed manually to its maximum 3200 setting resulted in heavy, detail-smudging noise reduction, but the results were still on the right side of acceptable.

^ A perfectly exposed shot with flattering colours and plenty of detail in the clouds and shadows. The castle looks sharp but focus deteriorates a little towards the edges and the grass texture is lost to noise reduction.  (1/800s, f/4, ISO 80, 24mm equivalent)

^ Another successful exposure, although there’s a slight graininess to skin textures on close inspection. (1/640s, f/4, ISO 80, 52mm equivalent)

^ The subtle textures in this wide-angle shot are smudged by noise reduction but it’s not a bad result. (1/50s, f/4, ISO 80, 24mm equivalent)

^ It’s a different story at the long end of the zoom in overcast weather. The narrow f/6.9 aperture has pushed the ISO speed up to 800, and combined with slightly soft focus, it’s a bit of a syrupy mess. (1/30s, f/6.9, ISO 800, 960mm equivalent)

^ Shooting at the long end of the zoom in direct sunlight gives much better results. There’s enough light to keep the ISO speed at its minimum setting. Focus isn’t pin sharp, though. (1/320s, f/6.9, ISO 80, 960mm equivalent)

^ Considering that some noise is visible even in bright conditions, image quality holds together well in low light. (1/20s, f/3.3, ISO 1000, 24mm equivalent)

^ I had to raise the ISO speed manually to 3200 to avoid motion blur in this telephoto shot in shady conditions. Details are smudged but it’s a surprisingly respectable result nonetheless. (1/20s, f/6.9, ISO 3200, 960mm equivalent)

^ For some reason the camera chose a 1/1,000s shutter speed for this static shot, pushing the ISO speed up to 250. There’s more noise reduction than is necessary but it’s far from a bad result. (1/1000s, f/3.3, ISO 250, 24mm equivalent)

^ This shot, on the other hand, could have done with a faster shutter speed to avoid motion blur. (1/60s, f/5, ISO 100, 131mm equivalent)

Conclusion

I’m not convinced that the 40x zoom is a big asset compared to the 30x and smaller zooms in other pocket ultra-zoom cameras. Personally, I’d much rather have a Panasonic FZ330 (or its more affordable predecessor, the FZ200) with its 24x zoom and constant f/2.8 aperture, but then that’s a bulkier camera so it’s an unfair comparison. I did manage to capture a few telephoto shots where everything came together — direct sunlight, a relatively sedentary subject with high contrast to help the autofocus — and the 40x zoom proved its worth.

Ultimately, though, the record-breaking zoom isn’t this camera’s defining feature. Its best photos are taken at more modest zoom positions, and these shots were generally excellent. The extra bit of zoom is there when you really need it, but don’t expect pixel-perfect shots. There’s not much to choose between this and the Panasonic TZ80 for image quality, so it’s more a question of whether to spend more on the TZ80’s superior video mode, touchscreen and electronic viewfinder.