Sony A7S II Performance

Generally good performance overall for its class, but with some sluggish areas.

Powerup to first shot was quite sluggish at about 2.9 seconds and slower than the A7S's 2.0 seconds. Switching from Play to Record mode and taking a shot was more reasonable at 1.1 seconds, but that's over twice as long as the A7S's 0.5 second in our test results.

The Sony A7S II's autofocus speeds were very good for a mirrorless ILC, and competitive with prosumer DSLRs in our static tests. The Sony A7S II's full-autofocus shutter lag (with the subject at a fixed distance) was 0.190 second in Single-area AF mode. This is just slightly slower than the A7S's 0.178s with the same settings and lens. When manually focused, the Sony A7S II's lag time dropped to 0.111 second, a little faster than the A7S's 0.129 second. The Sony A7S II's prefocused shutter lag time was only 21 milliseconds,which is again a little faster than the A7S's 24 milliseconds, and much faster than DSLRs. Note that these tests we done with Electronic First Curtain shutter enabled, which is the default setting. We did not test the A7S II in all-mechanical shutter mode, however with the A7S full AF shutter lag tested almost twice as long, and prefocused shutter lag was seven times longer.

To minimize the effect of different lens' focusing speed, we test AF-active shutter lag with the lens already set to the correct focal distance.

Single-shot cycle time was 0.56 second when shooting Large/Extra Fine JPEGs (using default Electronic First Curtain shutter). This increased slightly to about 0.6 second when shooting uncompressed RAW + Large/Fine JPEG files, but that's still quite fast. (Note that we no longer test single-shot mode with just RAW files, as the results are usually somewhere in between JPEG and RAW+JPEG. Also note that the A7S II cannot shoot Extra Fine JPEGs together with RAW files, falling back to Fine quality JPEGs when shooting in RAW+JPEG mode.)

Speed Priority Continuous mode managed five frames per second exactly meeting Sony's spec, though keep in mind autofocus is fixed at the first frame of a burst in this mode. (Unlike some other Sony A7-series cameras, the A7S II does not have on-sensor phase-detect AF pixels, so continuous autofocus is not supported in Speed Priority mode.)

Buffer depths were excellent even in Speed Priority mode, ranging 63 Extra Fine JPEGs to a worst case of 25 uncompressed RAW+JPEG frames. Note, though, that our target for this test was designed to be difficult to compress, so maximum burst lengths should be even longer with typical subjects when shooting JPEGs.

Buffer clearing times were long when shooting in Speed Priority mode, especially when shooting Extra Fine JPEGs. The camera does however let you make adjustments or take additional shots while writing to the card.

To see how much of a penalty shooting with the new uncompressed RAW option is for continuous mode in terms of buffer size and clearing times, we also shot with compressed RAW, and here are our results side-by-side:

As you can see in the table above, switching from uncompressed to compressed RAW files in Speed Priority Continuous mode increased the buffer depth by almost a third from 28 frames to 37 frames, and it reduced clearing time from 15 to 9 seconds. When shooting in Standard Continuous mode (which supports continuous AF), RAW mode buffer depth more than doubled from 31 to 71 frames, but clearing time actually increased from 15 to 19 seconds because of the much deeper buffer.

Incidentally, we did confirm the A7S II's uncompressed RAW files are indeed 14 bits by examining their linear data histograms in RawDigger, but only in single-shot mode. In either standard or Speed Priority continuous mode (and we believe in Silent Shutter, multi-shot and continuous bracketing modes as well), the effective bit-depth is reduced to 12 bits and converted to a 14-bit space. However these "12-bit" files are still uncompressed in the sense that they don't use Sony's lossy delta encoding as do compressed files. This drop in effective bit-depth to 12 bits in continuous modes is not new, though, as prior "14-bit" Sony models did the same thing before compression. We speculate this is probably due to sensor read-out speed limitations in 14-bit mode, as a number of cameras from different manufacturers are known to reduce sensor bit-depth in continuous or all-electronic shutter modes for performance reasons.

Bottom line, apart from slower power-on to first shot and play to record times, the Sony A7S II offers performance very similar or slightly improved over its predecessor, though unfortunately buffer clearing is still slow. The addition of an uncompressed RAW format is a welcome option, however the camera only produces true 14-bit ARW files in single-shot mode.

Decent battery life for a mirrorless camera.

The Sony A7S II uses a custom NP-FW50 rechargeable lithium-ion battery pack for power, and comes with a dedicated charger and an AC adapter for in-camera charging via USB. The battery is rated for 370 shots per charge when using the LCD monitor and 310 shots when using the electronic viewfinder, according to the CIPA standard. Although that's down 10 shots compared to its predecessor, battery life is still pretty good for a full-frame mirrorless camera, but poor compared to most DSLRs. An optional VG-C1EM vertical grip is available which doubles battery life with two batteries.

The table above shows the number of shots the camera is capable of (on a fully-charged rechargeable battery), based on CIPA battery-life and/or manufacturer standard test conditions.

(Interested readers can find an English translation of the CIPA DC-002 standards document here. (180K PDF document))