With 425 phase-detection AF points, continuous shooting at 11fps with autofocus, a 24.2-million-pixel APS-C CMOS sensor, 4K video capture and a whole host of other features, the Sony Alpha 6300 takes APS-C compact system cameras to a new level. Richard Sibley puts it through its paces.
Sony Alpha 6300 review – Continuous autofocus
With image quality from compact system cameras just as good as from a DSLR, manufacturers are now trying to tackle the areas that are typically weaker, including the speed of autofocus and, in particular, continuous autofocus. Panasonic has made good headway in this area over the past few years, and now it seems it is Sony’s turn to take up the mantle.
The first big step in taking on the the AF systems of DSLR cameras was when CSC’s introduced on sensor phase detection. This was a start in developing an AF system that was as fast as a DSLR in single AF mode, however continuous AF still struggled. With better algorithms and more processing power, this issue is slowly being addressed, and the Alpha 6300 may just be the tipping point where we can say that the £1,000 camera can continuously autofocus as good as an equivalently priced DSLR.
There are two high-speed continuous AF modes, and the camera is able to focus and meter from frame to frame in both. The difference is what happens between shots. The 11fps mode is faster, but doesn’t quite show a real-time preview between shots, whereas the 8fps mode does. The result is that the 8fps mode allows you to frame your subjects just as well as a DSLR.
Using the continuous AF tracking mode, the A6300 utilises a range of phase-detection points across the whole frame; however, it uses a higher concentration of points over the subject, so the camera uses the wide array to detect big jumps in motion, and the more defined range for the more precise jumps. This allows the camera to quickly process the AF position, but without having to continuously monitor all 425 AF points, which would take up a large amount of processing power. You can see the continuous AF in action quite clearly when you are using the camera. When you lock focus on to a subject you will see the AF points change shape and jump around as the subject moves, and although it doesn’t always seem very precise on the live view display, the resulting images are accurately focused.
In our tests, we found that the camera had no problem continuously autofocusing with a moderately moving subject such as a boat or a person walking or jogging. We tested it with a mountain biker, going downhill at a speed of approx 15-20mph, and found we were able to fire off a burst of shots in raw and JPEG mode, and nearly every single one was sharply focused. Where the images were out of focus were where the subject was very close to the camera, and therefore the lens had to make relatively greater jumps in the autofocus compared with the slighter ones from further away.
During testing we used the 16-70mm f/4 Zeiss lens, and tracking our mountain biker we found that the camera hadn’t locked the AF to the subject face, but to his coat, or the front of the bike. Knocking the aperture down to f/5.6 made a difference with the increased depth of field helping to improve the sharpness on the subject’s face.
Overall, the continuous AF is extremely impressive and can rival DSLRs in the same price bracket. However, as with all continuous autofocusing, the key is to make sure you familiarise yourself with how the system works so you can get the best results in a required situation.