Video quality

As with the a7R II, our studio scene shows the difference in detail capture between full frame 4K and Super 35 4K. However, if you ignore the Siemens stars, then you'll see the difference in detail capture isn't as dramatic as you might expect.

1080 footage is still substantially less impressive than 4K capture and there's much more of a difference in quality between full frame and Super 35 capture (with Super 35 mode being significantly less detailed). That difference extends to 120p shooting.

The Slow and Quick shooting modes let you choose the capture and playback speeds. Note that 12Mbps at 1/5th playback implies 60Mbps capture.

As with previous Sonys, if you let the camera slow down the footage from high frame rate capture, you find yourself limited to the 60Mbps mode, so we'd suggest shooting at 100Mbps 120p and performing the slow-down yourself, if you want to achieve maximum quality.

In the real world, all but the industry pros amongst us are unlikely to ever spot the detail difference between the Full Frame and the Super 35 footage.

Unlike the a7R II, there's no longer a significant difference in either the rolling shutter behavior or noise performance between the modes, meaning you can more readily intercut between footage.

Given how small the differences now are, we question Sony's decision to have the video mode default to Super 35 mode. It is slightly better but probably not by a large enough degree to justify the camera constantly reverting to crop mode, unless you disable it in the menus.

This second reel shows us some of the camera's other features, including image stabilization performance, rolling shutter during a pan, 60p and 120p footage and continuous AF.

Our assessment is that image stabilization is good enough to allow you to shoot short, hand-held clips but can't match the walk-and-shoot performance of cameras that combine sensor shift and digital stabilization. Autofocus (here set in 'Wide' area mode), can produce pretty good results if there's an unambiguous subject. For important projects we'd still suggest sticking to manual focus and perhaps using Spot AF to automatically pull focus between two subjects.

In these autofocus samples the camera is set to Wide area with Face Priority on (so chooses its subject based on how nearby it is and how close to the center of the frame, unless it finds a face in the scene). AF Drive Speed is set to fast and Tracking Sensitivity to 'Responsive' so that the camera errs towards refocusing if it detects a significant change in subject distance.

As you can see, the camera is fairly quick to reassess focus when the girl disappears from the center of the frame but reacquires her quickly when she returns. In the second and third clip, the camera stays focused on the nearest face, even if it's temporarily blocked, and generally will only refocus if it finds a closer face to jump to. In the final clip, the 'Responsive' setting prompts the camera to alternate between focusing on the girl's face and the proximal giraffe.