Image Stabilization

One of the a99 II's major selling points is the inclusion of 5-axis sensor-shift image stabilization, something that we've only seen on a full-frame sensor in Sony's own a7 lineup and the Pentax K-1. That alone makes it a bit rare.

24mm SteadyShot Off 24mm SteadyShot On 200mm SteadyShot Off 200mm SteadyShot On

We determined this system provided about 2 2/3 stops of compensation for this test. It is a strikingly similar performance to the a7R II, meaning there's no real advantage to choosing one or the other in terms of image stabilization.

Buffer Depth

The a99 II is the fastest shooting full-frame camera in Sony's lineup. The 'Hi+' drive mode fires with full AE/AF capabilities at 12 fps with the previous image captured displayed during the burst rather than a live update. The 'Hi' setting brings back live view in between shots, and reduces the speed to 8 fps. With the a7R II, the camera could only manage 5 fps without live view, and about 2.5 with.

The new front-end LSI chip brings a deeper buffer to the a99 II, as well as the ability to report back how many images are being written, and how far progress is on the file being currently written. You can even check focus on the shots that have been written to the card while the camera is still clearing its buffer - which makes the camera feel eminently more responsive than previous Sony cameras (like the a7R II).

When shooting uncompressed Raw in 'Hi+', the camera fired at a measured 11.5 fps at 1/250sec. The buffer filled up after 25 frames, and then took 35 seconds to clear with an SDXC U3 card. At this speed, the buffer will fill up after just over 2 seconds of continuous firing. The camera also allows reviewing of shots while the buffer clears, with a countdown of files being written displayed at the top. Annoyingly, the camera locks out the menus and certain functions in the Fn menu while the buffer clears, which forces the photographer to  waste time waiting for the buffer, instead of possibly making any on-the-fly adjustments.

Given the size of the files and the great speed at which they're being shot, we can't help but look at the a99 II's two card slots and wonder why a company that co-developed XQD cards and readers didn't put an XQD slot in place of one of the two SD slots. It would have helped the camera clear its buffer even quicker, which should be a primary concern when 12 fps is available. In our experience, however, using compressed Raw opens up a useful bit of space in the buffer, at the slight cost of quality when pushing files extensively.