No matter how good a photographer you are, it comes to nothing if you don't have a camera to hand. The downside of even the latest and greatest DSLR bodies and weighty collections of top-quality glass is that, when a fantastic photo opportunity presents itself, your kit is fast asleep in its gadget bag back at home.
In contrast, compact cameras are small and slimline enough to fit into a spare pocket, the glove box of the car, or just about anywhere else. Weighing in at 200-400g (0.4-0.9lbs), these cameras are lighter than most DSLR lenses without a camera attached, but can they really deliver in terms of image quality and creativity?
Just like most DSLRs, these cameras feature foolproof, fully automatic point and shoot modes, typically with 'intelligent' scene analysis. This helps them to deliver very good results in anything from portraiture to landscape photography, with the minimum of fuss and bother. However, you didn't go to all the time and trouble of learning advanced photographic techniques just to let your camera make all the important decisions for you.
The most powerful thing about high-end or power compacts is that they're not limited to auto shooting modes and give you full creative control. Advanced PASM shooting modes are supplemented with choices for different metering and autofocus modes, manual focusing, white balance tweaks and more besides. Crafty scene modes are also on hand to make the most of the trickiest of subjects.
However, you can have all the shooting options in the world but if you can't get at them quickly and easily, they might as well not be there. Compared with DSLRs, the physically small size of compact cameras makes it more challenging to put important shooting parameters under photographers' fingers and thumbs. Clever designs and customisable function buttons can go a long way to delivering easy access to the settings you want to get at in a hurry.
Full-frame DSLRs are becoming increasingly popular, even in consumer class cameras, and use an image sensor that measures 36 x 24mm. Even APS-C format DSLRs have (approximately) 24 x 16mm sensors, but just how big are the sensors in current compact cameras?
The Sony RX1 actually boasts a full-frame sensor but, really, who wants to spend £2,500 / AU$3,000 / US$2,800 on a compact camera? We've not included this camera in the test group, instead going for more traditional fare with much lower price tags.
By far the most popular sensor size for this class of high-end compact camera is 1/1.7-inch, which equates to dimensions of 7.6 x 5.77mm. The Fujifilm X20 uses a slightly larger 2/3-inch sensor, which measures 8.8 x 6.6mm. In both cases that's a great deal smaller than the sensor of an APS-C format camera. The Sony RX100 goes even further to bridge the gap, with a 1-inch sensor that measures 13.2 x 8.8mm.
It's a sign of the times that, since we last ran a group test of high-end compacts about a year ago, image resolution has crept up from 10MP to 12MP in most cases. The Panasonic LX7 is the only camera in this group that sticks with the same 10MP resolution as its predecessor, the Panasonic LX5. The Sony leads the resolution race with a 20.2MP image sensor, made more achievable by its physically larger dimensions.
Noise and depth
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A major drawback of the relatively small image sensors fitted to most compact cameras is that each photosite can only gather a relatively small amount of light. Go back a few years and image quality was notoriously poor in very low lighting conditions. This was true even when using low sensitivity settings, while images became horribly noisy when switching to high ISO ratings.
The problem has been tackled with advanced sensor designs, for example using micro lenses so that each photosite can gather more light, along with backlit or 'back-illuminated' sensors.
Here, the wiring and circuitry that does the job of powering the sensor and passing on information to the image processing engine is relocated around the back of the sensor. This means that the amount of light reaching the photosites isn't diminished at all.
Most cameras in this class now also feature 'faster' lenses. These have wider maximum apertures that allow more light to pass through to the sensor. As well as helping in low lighting conditions, there's another bonus when it comes to reducing the depth of field.
Due to the smallness of the image sensors, the actual (rather than effective) focal length of compact camera lenses is very short. This tends to give a large depth of field, ideal for landscape photography, but it's a bit of a pain when you want to blur the background for portraits and still life images.
Wider maximum aperture ranges of around f/1.8-2.8 really help to narrow the depth of field. And to make those wide apertures available even in very bright and sunny lighting conditions, many of the compact cameras in this group feature built-in ND (Neutral Density) filters which you can switch in as a menu option if you want to.