One of the reasons for choosing a CSC is the ability to change lenses
cameras add two more. The smallest is the 1-inch sensor size used in Nikon 1 cameras. The picture quality takes a hit, but this sensor is still a lot larger than the average compact’s, so the pictures still look good.
The next size up is the Micro Four Thirds format used by Olympus and Panasonic. This is about half the size of the APS-C format, but these sensors have come a long, long way, to the point where they’re closer in quality to APS-C sensors than they have any right to be.
APS-C is the next size up and is used by Fuji in its X-mount cameras, as well as by Sony in its mirrorless Alpha models.
But Sony also makes the full-frame A7series cameras. These are pitched pretty high, and while they’re just about affordable for amateurs, Sony is aiming at the pro market.
Autofocus systems are constantly evolving, and they make a major selling point for CSC makers. The areas to look out for are AF points, AF speed and what kind of AF is offered.
Generally, the more AF points the better, because it usually means they’re spread over a larger area of the screen and form part of a more sophisticated autofocus system.
AF speed is trickier because makers like to quote the minimum response times, assuming the best-possible conditions. Usually, though, if a maker boasts about the response time, it’s probably engineered a pretty fast system.
As for the different kinds of autofocus, phase-detection AF is the big story right now. This overlays image data from two different positions, which tells it not only how much to refocus the lens, but in which direction too.
Regular sensor-based contrast AF – the primary system for CSCs until now – moves the lens one way and then the other to find the point where the image is at its sharpest. It’s precise but the process is slower.
Until now, phase-detection autofocus has been exclusive to DSLRs via dedicated AF sensors in the camera’s body. But makers have figured out how to incorporate phase-detection pixels into the design of the camera sensor to produce hybrid phase-detection-and-contrast AF systems that offer the best of both worlds. Phase-detection AF is a feature worth having, and has helped close the AF performance gap between DSLRs and CSCs, particularly for action photography and subject-tracking.
Making movies
CSCs also have advantages for movie makers. The always-on live view is perfect for filming, and compact system cameras generally offer much better live-view autofocus (though Canon does offer Hybrid CMOS AF and Dual Pixel CMOS AF in some of its DSLR models).
CSC makers are working hard to stay ahead of the movie-making game, especially with 4K video. Right now, you might think 4K is overkill, but in a few years’ time you might be glad you shot your home movies in proper high-res and not in old-fashioned HD.
Aside from 4K, there’s also the rise of in-body 5-axis image stabilisation, which goes beyond steadying up stills photography to control the type of camera movement characteristic of handheld video. Olympus and Sony have got this working nicely now.
Lens choice
As you might expect, each maker uses its own bespoke lens mount, and in the case of Sony – which makes cameras with two sensor sizes – you get two ranges of lens even within that brand (Sony E-mount lenses come in APS-C and full-frame varieties).
Things are somewhat simpler if you choose a Panasonic or Olympus camera. They both use a common Micro Four Thirds lens mount. This is one of the earliest mirrorless formats, so not only have lenses been coming out for longer, they’ve been arriving from two different makers. These lenses are interchangeable between brands. There may be certain restrictions on functions but, broadly, you can freely use Olympus lenses on Panasonic cameras and vice versa.