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Saterdag 27 April 2013

Canon Powershot G15 Review


A few years ago Canon's G-series was the place to look if you were in the market for a 'serious' compact, but more recently there has been a lot of development in this sector of the market. These days there is an entire range of cameras to choose from - all with slightly different strengths and weaknesses. As a consumer this is fantastic, but it does mean that your buying decision is harder now than it was. You need to honestly assess what's most important to you in your photography and then make the appropriate choice.

If you are looking for a pocketable 'enthusiast' camera the Sony RX100 with its large 1" sensor provides the greatest pixel count, the Panasonic LX7 comes with the fastest lens, and Fujifilm's X10 and XF1 offer the innovative EXR sensor with its impressive dynamic range and high ISO performance options (in 6MP mode). However, if an abundance of external controls, responsive operation, bomb-proof build quality and pocketability are high up on your list of priorities the G15 is definitely worth looking at.

In reality the choice for many buyers will be between the G15 and the Nikon P7700, which with its 28-200mm lens is the only other camera in this class to offer a lens longer than 120mm. That said, at F4 its lens is a stop slower than the G15 at the tele end. The Nikon comes with an articulated screen and a similar level of external control as the G15, but its body is larger than the Canon and lacks an optical finder. We're looking forward to putting the Nikon through our review process and see how the two cameras perform head-to-head, but for now, you can use our image noise and studio scene widgets to compare the cameras' image quality.

Ultimately the competition is fierce in the enthusiast compact sector and no matter what camera you choose you'll have to compromise in some area or another. That said, with its combination of very decent image quality, responsive operation, quick AF, excellent build quality and its versatile and fast lens, the Canon Powershot G15 is a safe bet for most photographers looking for a 'serious' compact.
Image Quality

The Canon Powershot G15 produces very good image detail at lower sensitivities and shows a good balance between noise reduction and detail retention as you go up the ISO scale. Focus and metering are consistently reliable, even in difficult lighting situations.

However, the Canon G15 has a relatively small 1/1.7" CMOS sensor that comes with the limitations we are used to seeing on many small-sensor cameras. Dynamic range in highlights isn't fantastic, and the camera tends to deliver relatively bright midtones, and what this means is that in high-contrast scenes you'll often have to deal with overblown skies and other burnt out image areas. Some of this lost highlight detail can be pulled back in raw conversion, though.

High-ISO noise is well-controlled by the JPEG engine but a lot of fine detail is blurred by noise reduction from ISO 400 upwards, at default NR settings. That said, even the highest ISO settings 6400 and 12800 are usable at modest output sizes. The G15's fast lens also means you can keep the ISO sensitivity lower than on cameras with smaller maximum apertures, which means better image quality, or alternatively use faster shutter speeds - great news if you're shooting moving subjects.

Ultimately the G15 offers very good image quality for the size of its sensor, but if you are in the market for a compact camera and image quality is your highest priority cameras such as the Sony RX100, Canon's own G1 X or slightly larger mirrorless models such as the Panasonic GX1 or Olympus E-PL5 might be a better option. Of course none of these models offer the same combination of a fast and versatile lens, compactness and manual control as the G15.
Handling and Operation

In our review of the Canon Powershot G12 we found the G15's predecessor to be one of the best-handling compact cameras on the market. The new model, with its two customizable control dials, dedicated exposure compensation dial and sensible ergonomics throughout follows right in those footsteps. However, there are a few differences you should be aware of.

In terms of operation and handling the main differences between the G12 and G15 are the increased AF speed and the lack of a swivel-screen and dedicated ISO dial. The AF speed on the G15 is noticeably and measurably snappier than on previous G-series models which, in combination with the responsive overall operation, makes the camera very pleasant to use. While the loss of the ISO dial is a shame, it's compensated by the much better positioning of the exposure compensation control which is very easy to use with your thumb. ISO can still be accessed quite easily via a dedicated hard-button on the multi-controller.

The loss of articulated screen will annoy some people but it's not all bad as it means you get a slimmer camera with a larger screen. The G15 feels indeed more pocketable and compact than its predecessor but there's no doubt that a swivel screen offers more flexibility when shooting from high or low angles.

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Canon's PowerShot G-series is one of the most iconic lines of digital compact cameras, with the original G1 having debuted right back in September 2000. The original models sported fast lenses, articulated LCDs, optical viewfinders, Raw data recording and lots of external control, and were aimed at tempting enthusiasts who usually shot with 35mm SLRs to dip a toe into the brave new waters of digital photography.

The line took a hiatus for a couple of years between 2004-6 when affordable APS-C SLRs started to appear, before being reinvented with the smaller, slimmer G7 - redesigned as a compact camera for SLR-owning enthusiasts. To the dismay of many G-series fans, the G7had a slower lens, fixed screen and didn't record Raw. Since then the G7's design has provided the basis for a number of subsequent models, adding back Raw and the swivel screen along the way, right up to the G12 that's been on the market for two years. In the meantime Canon created the G1 X - a variant on the same basic design with a much-larger sensor, and at a correspondingly higher price-point.

Now, with the launch of the G15, Canon has added back one of the original selling points of the G-series; a genuinely fast zoom lens. This covers the same 28-140mm equivalent focal length range as the G12's, but is a stop and a third faster, at F1.8-2.8 rather than F2.8-4.5. This gives the G15 a distinct advantage over its predecessor not only in low light, but also in the ability to blur backgrounds a bit more when shooting at the long end of the zoom.

But while Canon gives with one hand, it takes away with the other. The G15's rear screen is fixed, rather than articulated, a move that Canon says was necessary to make the camera smaller and more pocketable. The G15 is indeed significantly slimmer than its predecessor - by about 15% with the lens retracted - but we can't help but feel that as many potential buyers will be dismayed by the loss of this useful feature as there will be enthusiasts who are delighted by the camera's portability. The G15's screen itself is a large, high-resolution 3" 920k dot unit with a tempered glass cover and a wide viewing angle.
Canon PowerShot G15 key features

    12MP 1/1.7" Canon CMOS sensor
    28-140mm equivalent F1.8-2.8 lens, 4-stop 'Intelligent IS'.
    DIGIC 5 processor
    ISO 80-12800
    Fixed 3" 920k dot PureColor II G screen
    Optical viewfinder
    Raw format recording
    Dual-axis electronic level

The G15 uses a Canon-made 12.1MP 1/1.7"-type CMOS sensor, the same as that found in the co-announced S110 (and similar to the one used on the S100), which offers an ISO range from 80 to 12,800 in concert with the DIGIC 5 processor. As we'd expect, Full HD movie recording is available, at a framerate of 24 fps and stereo sound from the built-in microphones. The G15 also (finally) gains a dedicated movie record button, for the first time on a small-sensor G, and the lens can zoom and focus during recording.

One notable improvement from the G12 is distinctly quicker autofocus - 53% faster, according to Canon - which if true, would make the G15 the fastest-focusing compact the company has made. The G15's CMOS sensor also enables rapid continuous shooting at 10 frames per seconds, although only in the somewhat-restrictive High Speed burst HQ mode. In other modes the G15 will shoot at 2.1 fps.

Body & Design

The G15 sports an angular, minimalist design that takes many of its cues from the G1 X, although it's not quite so sharp-edged. Aside from the fixed screen the body layout is almost identical to its larger-sensored cousin, which means the loss of the ISO dial compared to the G12, with this function now accessed via the 4-way controller. The flash is now of the pop-up type, released by a sliding switch on the top plate.

The G15 sports a huge array of external controls for such a small body, including twin control dials front and rear to go with the top-plate mode and exposure compensation dials. The G15 is also one of those increasingly rare cameras that still has an optical viewfinder, and the side views above show how the fixed LCD has allowed Canon to create a distinctly more-slender body than the G12, as well as fitting in a slightly larger screen.

Operation & Performance
The G15's top-plate is home to the pop-up flash on the left and power button, shutter button/zoom rocker, mode dial and exposure compensation dial to the right of the viewfinder hump. The layout is very similar to the G1 X, but the repositioning of the exposure compensation dial means it's easier to operate using your thumb without loosening your grip of the camera.

The hand grip is slightly less protruding than on the G1 X, but thanks to its soft rubber material and the G15's lower weight and smaller dimensions, it works well and ensures a stable hold of the camera. Like on the G1 X the pop-up flash on the left is operated with the adjacent slider ( the G12 had a fixed unit at the front of the camera).

The G15 is very similar to both the G12 and G1 X in terms of operation. For a compact camera it has an unusually large number of external controls, including a dedicated video button. This allows you to change many crucial shooting settings at the press of a button or, in the case of exposure compensation, the turn of a dial. The new model is only marginally smaller than its predecessor, but without the protruding swivel-screen the G15 feels noticeably less chunky than the G12 and is an easier fit for many coat pockets.

The build-quality is as good as it gets. The camera feels like a mini-EOS 1D, extremely solid with soft and comfortable rubberized hand grip and thumb rest. The magnesium alloy surfaces have been very slightly roughened, giving them a quality feel. It'll be hard to find another compact camera that feels this well put together. That said, the new G15's metal body is a touch more matt than the G12's, and while this gives the camera a very attractive appearance the surface is more prone to scratches and abrasion.

The camera rear features exactly the same control layout as the the G15's large-sensor cousin, the G1 X. Most buttons are located to the right of the screen. There's also a combined control dial/multi-controller that lets you access ISO, focus mode, flash settings and display mode. A press of the center button opens the FUNC-menu that lets you adjust further shooting parameters. The function of both the front and rear dials is customizable.

Above and below the multi-controller you find another four buttons - AF area selection, AE-lock, metering mode and the Menu button. The top right corner of the camera rear is the location of the video button, the play button is just to the right of the viewfinder and the only button on the left side is the customizable Shortcut-button. It can be programmed to have one of the following functions:

Overall handling and performance

The G15 is an evolutionary update from the G12, and on the whole the changes Canon has made look sensible and well-considered. In terms of operation and handling the main differences are the increased AF speed and the lack of a swivel-screen and ISO-dial.

Canon says the G15's AF is 53% faster than the (already quite snappy) G12 at wide-angle (CIPA-standard) and while we have no way of precisely measuring the differences we have tried both cameras side by side in varying conditions and can confirm that the G15 is noticeably quicker and one of the fastest focusing compact cameras we have tested. In real-life conditions we would estimate the G15 to be between 20 and 30% faster than its predecessor. The AF also works reliably down to fairly low light levels, although it slows down a little in dimmer conditions.

In terms of continuous shooting the G15 has been improved over its predecessor as well. That said, at 2.1 frames per second it is still not blisteringly fast. The table below shows you our measured frame rates for JPEG and Raw. The good news is that you can shoot at these rates until your card runs full, the bad news is that you only achieve these rates at the long end of the zoom and at certain settings. The JPEG rate goes down to approximately 1.8 fps at wide-angle and slows down a little further at higher ISOs and with noise reduction set to 'High'.

If you need more speed you can switch to the High-speed Burst HQ mode. However, this being a scene mode you have no control over shutter speed, ISO or indeed any other shooting parameter, although you can apply exposure compensation. In this mode the camera will take exactly 10 frames in one second. You'll then have to wait for the buffer to clear, which takes approximately five seconds, before you can press the shutter button again to shoot the next burst.

While the loss of the ISO dial is a shame, it's compensated by the much better positioning of the exposure compensation control which is very easy to use with your thumb. ISO can still be accessed quite easily via a dedicated hard-button on the multi-controller.

What's bound to be contentious, though, is the reversion to a fixed, rather than articulated, screen. This means you get a slimmer camera with a larger screen - something Canon is at pains to point out - and the 920k dot unit used is one of the best on any compact. But there's no doubt that a swivel screen offers more flexibility while shooting.

Despite the removal of the ISO dial the G15 offers one of the most extensive sets of external controls on any compact camera. Like its predecessor the G15 has both rear and front control dials which pretty much means you can operate the G15 like a mini DSLR. The rear dial is fine, but like most dials on a multi-controller is a little tricky to operate with cold or gloved fingers. By default, the front control dial changes aperture and shutter speed in Av and Tv modes, and shutter speed in manual exposure mode, but the behaviour of both dials can be customized if desired.

Overall the Canon Powershot G15 is one of the best-handling compact cameras we have seen for a while. It turns on very quickly and is generally very responsive, all important shooting settings are accessible via a dial or button, and with its high quality materials it simply feels nice in your hands.

Features


The G15's feature set, design and operation is very close to its predecessor G12 but there are some key differences. The G15 has a faster lens, a higher resolution movie mode and offers ISO 6400 and 12800 at full resolution. On this page we will concentrate on examining these new features but we have also included some features that were available on the G12, such as Raw shooting, in-camera HDR and digital filters.
Fast lens

With the launch of the G15, Canon has added-back one of the original characteristics of the G-series; a fast zoom lens. It covers the same 28-140mm equivalent focal length range as the G12's, but is a stop and a third faster, at F1.8-2.8 rather than F2.8-4.5. As we mentioned in the introduction to this review, this should give the G15 a distinct advantage over its predecessor in poor light since the G15's faster lens means that at any given light level you can keep the ISO at a lower setting, capturing better image quality with more detail.

The different sensor sizes of the cameras in this class make it difficult to directly compare their lenses. The graph below shows the equivalent apertures* of each camera available at each equivalent focal length. This makes it easy to visualize the lens ranges of the cameras and also means you can see which camera will offer shallowest depth-of-field at any given focal length.

RAW shooting

The Canon Powershot G15's ability to record Raw files allows you to modify many shooting and image parameters such as white balance, sharpening, noise reduction, and to a degree even exposure in post-processing. As you can see if you look at the full-size version of the sample shot below converting your Raw files in Adobe ACR 7.3. only gets you a minimal amount of additional detail, the G15's JPEGs simply show very good detail already.

However, Raw processing can still be very useful to recover highlight detail that has been lost in the out-of-camera JPEG. In our JPEG sample the sky has been 'blown out' and shows no detail at all. By pulling the Highlights slider in Adobe ACR 7.3 Beta all the way back we have been able to recover much of the blue sky and clouds, greatly improving the image.

 Resolution Chart Comparison (JPEG and RAW)

Images on this page are of our standard resolution chart which provides for measurement of resolution up to 4000 LPH (Lines Per Picture Height). A value of 20 equates to 2000 lines per picture height. The chart is shot at a full range of apertures and the sharpest image selected. Studio light, cameras set to aperture priority (optimum aperture selected), image parameters default. Exposure compensation set to deliver approximately 80% luminance in the white areas.

What we want to show here is how well the camera is able to resolve the detail in our standard test chart compared to the theoretical maximum resolution of the sensor, which for the charts we shoot is easy to work out - it's simply the number of vertical pixels (the chart shows the number of single lines per picture height, the theoretical limit is 1 line per pixel). Beyond this limit (which when talking about line pairs is usually referred to as the Nyquist frequency) the sensor cannot faithfully record image detail and aliasing occurs.

This limit is rarely attained, because the majority of sensors are fitted with anti-aliasing filters. Anti-aliasing filters are designed to reduce unpleasant moiré effects, but in doing so, they also reduce resolution (the relative strength and quality of these filters varies from camera to camera). In theory though, a sensor without an AA filter, when coupled with a 'perfect' lens, will deliver resolution equal to its Nyquist limit. Therefore, even though it may be effectively unattainable with normal equipment in normal shooting situations, an understanding of a sensor's theoretical limit provides a useful benchmark for best possible performance. Nyquist is indicated in these crops with a red line.

On this page we're looking at both JPEG and Raw resolution. For a (more) level playing field we convert the latter using Adobe Camera Raw. Because Adobe Camera Raw applies different levels of sharpening to different cameras (this confirmed) we use the following workflow for these conversions:

  1.     Load RAW file into Adobe Camera RAW (Auto mode disabled)
  2.     Set Sharpness to 0 (all other settings default)
  3.     Open file to Photoshop
  4.     Apply a Unsharp mask tuned to the camera, usually 100%, Radius 0.6, Threshold 0
  5.     Save as a TIFF (for cropping) and as a JPEG quality 11 for download

The Canon Powershot G15 does well in our resolution tests, resolving all nine lines accurately up to around 2250 LPH in the camera's JPEG mode. Converting your RAW files gives you some additional detail, resolving the chart up to around 2400 LPH with some 'false detail' beyond that. This is getting pretty close to the Nyquist limit, which is equal to the G15's vertical output pixel count - i.e. 3000 pixels/LPH.

Conclusion - Pros
  •     Good low-ISO image detail and reliable metering
  •     Versatile, sharp and fast 28-140mm F1.8-2.8 lens
  •     Good balance between noise reduction and detail retention at higher ISOs
  •     Fast and responsive operation
  •     Very pocketable format
  •     Fast and reliable AF system
  •     Very effective Image Stabilization system
  •     Excellent 920k dot screen
  •     Optical viewfinder useful in very bright light (but is relatively inaccurate, and has no shooting info)
  •     Lots of external controls including two control dials and an exposure compensation dial
  •     Customizable control dials and Shortcut-button
  •     Excellent build quality and body materials
  •     Decent battery life

Conclusion - Cons
  •     Exposure compensation dial does not work in video mode (but you can set exposure compensation using the AEL button when the mode dial is set to movie)
  •     No swivel screen (vs predecessor and some competitors)
  •     No automated panorama mode (only stitch-assist)
  •     HDR mode only works well with the camera on a tripod
  •     Auto ISO only uses up to ISO 1600
  •     Matt surface a little prone to scratches


Overall, despite the removal of the ISO dial the G15, like its predecessor, offers one of the most extensive sets of external controls on any compact camera. It has customizable rear and front control dials and can therefore be operated in an almost DSLR-like fashion. Its compact size in combination with the snappy operation and well thought-out user interface make the G15 a great camera to shoot with.

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