We've come to expect good all-round image quality from Canon, and the new 12.1 million pixel CMOS sensor certainly doesn't disappoint. In our test shots, we found the SX510 HS capable of automatically handling a wide range of light conditions as well as offering full manual flexibility.
Evaluative metering generally provided good results, except in extreme lighting conditions, while spot metering gives good control. The metering system managed to handle complex lighting situations such as dappled sunlight and it felt equally stable in low light situations. White balance provides solid, true to life, colour reproduction on automatic, while a full range of lighting specific options and custom setting allow for full control.
The sensitivity may be capped at the ISO 3200 mark, but this proves to be a good thing, as quality within this range is generally good. The new High Sensitivity system appears to do a great job of preventing loss of detail at high sensitivity settings. You can still expect to see some colour speckling as you pass the ISO 1600 mark, but the quality is very solid compared to other compact cameras.
Although it's not possible to manually select it, the Low Light scene mode offers sensitivity up to ISO 6400, at the cost of resolution. In this way, it's possible to get stable shots even in low light conditions, although you do suffer the same noise you'd expect when increasing sensitivity manually.
Images are sharp across most of the centre frame, and subjects appear crisp overall. There is some understandable chromatic aberration and colour fringing at the very edges of the frame, especially when at the telephoto end of the lens, but it doesn't detract from an overall good image quality. There is a small amount of distortion at the wide end of the lens, which is natural given the focal length.
Autofocus is responsive and fast, even in low light, a fact most likely attributed to a bright and clear focus assist light. In tracking modes, the AF was responsive at following the subject and in Zoom Framing Assist mode, faces were tracked fast and zooming occurred smoothly. Overall, the autofocus is very capable and should be able to cope with almost any situation.
Even though the star feature of this model is the long focal range, it's equally capable at macro photography. A 0cm focusing range means that you can literally press the lens up to the subject and still manage to focus - provided there's enough light, of course. Tracking options work just as well at macro distance as they do in normal conditions and overall it's very easy to focus on just about anything.
The Intelligent Stabilization system is extremely capable and it's possible to get some very clear pictures at surprisingly low shutter speeds – provided you have a steady hand. This is an area where the camera's weight pays off, being so light means that your hand isn't strained and shakes less. The system makes it entirely possible to hold a subject steady at telephoto distances, which makes a big difference with a lens this size.
The 3-inch LCD screen is bright and gives good image previews and field of view is as good as we'd expect. The screen suffers from glare in bright conditions and it can become hard to accurately judge exposure and colours when in direct sunlight. The lack of an optical or electronic viewfinder can make this a problem, but in general, we managed to cope just fine and it certainly isn't a deal breaker. Sadly the screen is neither touch sensitive nor articulated, but we consider this easy to accept given the size of the camera.