Rabu, 02 November 2011

Canon PowerShot SX150 IS review

Canon PowerShot SX150 IS review
Canon PowerShot SX150 IS front view, flash and shutter open

Good

  • Inexpensive
  • Sharp pictures
  • Great colours

Bad

  • AA batteries
  • Some noise in deep blue
This is one of the cheapest digital superzooms you can buy. Just £150 will bag you a 12x zoom and a 14.1-megapixel sensor. Add to that a clutch of creative digital filters and a smart auto-shooting mode, and the plain, chunky PowerShot SX150 IS looks very tempting indeed.

Features

The PowerShot SX150 IS has much in common features-wise with some far more expensive cameras in Canon's current line-up. As well as the regular auto mode in which we performed the majority of our tests, it has eight scene modes. There is a choice of creative filters, including toy camera, monochrome, colour swap and miniature effect, which mimics the results you'd get from using a tilt-shift lens to make your scene look like a model.
Canon PowerShot SX150 screen and features
The PowerShot SX150 IS shares features in common with more expensive cameras in Canon's range.
What it doesn't have is a back-illuminated charge coupled device (CCD) -- the digital camera's equivalent of film that converts light into electrical charges -- that increases the level of low-light captured in night sky photography, for example. Nor does it have the high-sensitivity features rolling out across the upper-end of the range. This is reflected in the lower price.

Shooting stills

Despite this, it demonstrated excellent dynamic range throughout our tests, balancing images with extremes of both highlight and shadow, minimising the amount of clipped detail at the upper end of the scale and retaining plenty of information at the lower end. This allowed us to apply minor tweaks to the fill light, recovery and exposure levels in post-production to bring out parts of the image that would otherwise have been lost.
Canon PowerShot SX150 IS detail test
The PowerShot SX150 IS maintained an excellent level of detail in demanding lighting conditions, as seen in this image, where detail has been retained in the background despite the frame being dominated by a bright chrome ball (click image to enlarge).
It consistently made good use of available light to avoid either hiking the sensitivity -- and thus increasing noise in the image -- or calling on the flash, which in many situations would not have sufficient throw to illuminate the whole scene.
In complex shots with plenty of detail, such as the flower stall below, it maintained a good depth of field. Despite self-selecting an aperture of f/3.4, the stall remained in focus through three-quarters of the frame. There was no evidence of unduly heavy JPEG compression, which we might have expected to see in more complex areas of the image, such as the grass in the lower left corner.
Canon PowerShot SX150 IS detail test
A good depth of field and sharp detail brought this shot to life (click image to enlarge).
There was, however, some fringing on the white paper price tags where the lens had failed to accurately focus each part of the spectrum on the same part of the sensor. In particular, the '8=' tag in the lower left, '7.50' in the upper-left quarter and '£3' in the centre of the frame all showed evidence of a pink fringe -- known as chromatic aberration -- on their top and left edges.
Canon PowerShot SX150 IS - evidence of some chromatic aberration
Examining the shot at close quarters revealed some evidence of minor fringing against strong contrasts.
This effect was evident in other images too, but in all cases it was minor and only visible on close inspection. We would not expect it to impact the quality of a printed image, or indeed any photo used at common web resolutions.
The PowerShot SX150 IS demonstrated excellent colour reproduction right across the visible spectrum. The market stall below features the full gamut of common tones, including man-made blue and red (the bag in the foreground) and natural hues in the vegetables. With white balance left to automatic, the PowerShot SX150 IS rendered each with great clarity, reproducing the colours accurately.
Canon PowerShot SX150 IS colours test
There are plenty of tones in this image that were handled well by the PowerShot SX150 IS (click image to enlarge).
This performance wasn't limited to brightly coloured scenes either. When tasked with capturing a more muted, narrow palette, such as this archway stall, which is predominantly brown and fairly dark, it achieved a good result. It retained plenty of detail in the brickwork with a smooth, controlled transition in the shadow under the archway.
Canon PowerShot SX150 IS muted colours test
The PowerShot SX150 IS did an excellent job of retaining detail in this darker image despite the limited colour palette (click image to enlarge).
To achieve this it increased its sensivitity to ISO 400 and reduced the shutter speed to 1/30 second. This resulted in a noticeably grainier result when zoomed to 100 per cent. This isn't unexpected at such middling sensitivities, but we were more concerned to see this grain also creeping in at ISO 100 in an otherwise well-lit scene.
In the below image of Southwark Cathedral, the sky exhibits considerable dappling where we would have expected to see a smooth, clean blue. When viewed full-screen rather than zoomed to 100 per cent it's not obvious. Even so, we would have expected to see much clearer, cleaner results.
Canon PowerShot SX150 IS noise in sky
The below image zoomed to 100 per cent shows some evidence of noise in the deep blues of the sky.
Canon PowerShot SX150 IS noise test
Despite it being exposed at just ISO 100 there was more-than-expected grain in the sky (click image to enlarge).
This effect was much less obvious on lighter skies such as the one seen in the wide-angle shot of our zoom test, below. This was despite the frame having been shot at a higher sensitivity -- ISO 160 -- indicating that the noise is due not so much to the increase in sensitivity as the tone captured. Here, the blue is far less vibrant than the sky surrounding the cathedral.
Canon PowerShot SX150 IS zoom test
The PowerShot SX150 IS makes short work of finding the exact framing you're after with a 12x zoom (click image to enlarge).
The PowerShot SX150 IS has a 12x zoom lens, equivalent to 28-336mm on a conventional 35mm camera. Even in a fairly chunky camera such as this it remains impressive and makes for far more versatile shooting. This is helped by a lens shift-based stabilisation system to smooth out the effect of shaking hands at long zooms or in low light, which helped greatly in our above potato stall image -- taken without the aid of a tripod -- despite the muted lighting.
The closest focusing distance is just 1cm, which is great for macro photography. At the same time the aperture range is slightly underwhelming. With the lens fully retracted it tops out at a run-of-the-mill f/3.4, and f/5.6 at full telephoto. Meanwhile, sensitivity runs on a scale of ISO 80 to ISO 1,600, with compensation of +/- 2 EV in 1/3 stop increments. The slowest shutter speed is 15 seconds; the fastest being 1/2,500 second.

Shooting video

The PowerShot SX150 IS has both a dedicated video mode, accessed using the mode selector on the top of the body, and a quick-record feature, courtesy of a recording button on the back of the body. The former, naturally, gives you access to more features, including the ability to apply the same effects filters as you can with stills.
The results are impressive, with sharp images and vibrant colours, as we had come to expect from our experience of shooting stills with the PowerShot SX150 IS. It had no trouble maintaining a fix on the focus as we reframed out shots, and the zoom was quiet enough not to be evident on our soundtrack. However, the rotating cuff around the shutter release, through which it is controlled, did click as we released it on each occasion and this can be heard on the finished video.
The soundtrack was extremely clearly recorded, and we were very impressed by the way that the dual front-facing microphones, positioned on either side of the lens, managed to accurately capture distant sound sources, such as the singing of a busker in a bin (yes, really), or the knocking of punting poles, both of which feature in our test footage.

AA batteries

The PowerShot SX150 IS is the most conventional camera we've tested in a long while. Its curvy swoops make it look about 10 years old, while inside the grip you'll find not a single bespoke battery, but a pair of AA cells.
Canon PowerShot SX150 IS curvy design
The curvy swoops of the Canon's conventional design age it by a decade.
That's a shame, as powering a camera, with its illuminated screen and articulated lens array, is a demanding task. It's a job that's often best left to a bespoke battery source designed specifically with that task in mind.
The bundled cells were exhausted after shooting just 65 photos and 3 minutes and 17 seconds of video. While there's much to be said for the ease with which you can buy replacements, that makes this an expensive camera to run. You can, of course, travel with a charger and replacement rechargable AAs, but for our money it's much more convenient -- and preferable -- to use a dedicated camera battery; in our experience they last longer than these did.

Conclusion

The battery issue was our only real complaint where the PowerShot SX150 IS was concerned. However, we do remain a little concerned by the dappled noise introduced when shooting the particular shade of blue that appeared in our shot of the cathedral sky, as it also appeared in a blue sign of a very similar tone.
If you're prepared to invest in a set of rechargable batteries -- even if they're not Canon's optional extras -- and travel with these and a charger, then the PowerShot SX150 IS represents a great, ambitious entry into digital photography. It's a significant step up from a four or five-year-old mid-range shooter.
You're getting an awful lot of camera for £150 here, not only in terms of physical size, but features too.

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