Image Stabilization

Upon first shooting with the a7 II, we were really disappointed with the IS performance. One firmware update later, and the a7 II was a whole new camera. Firmware 1.1 gave the camera the ability to start IS when the shutter is half pressed, making a massive difference in the a7 II's real world stabilization capabilities.

We tested the a7 II's IS performance by shooting 10 frames at our test target, starting with one over the focal length, and working our way downward in intervals of 2/3-stops. We first did this with IS on, and then with IS off. The images were then assessed to the following standard:

Excellent Some softness
Noticeable blur Unusable

1) Excellent - the best the camera is capable of
2) Some softness - only distinguishable from Excellent by comparison
3) Noticeable blur - blur can be perceived without reference to another image
4) Unusable - significant motion perceptible

24mm Equivalent
55mm Equivalent
200mm Equivalent
Stabilization On Stabilization On Stabilization On
Stabilization Off Stabilization Off Stabilization Off

To ensure we could keep our aperture consistent at each of the tested shutter speeds, we shot using a variable neutral density filter on the front of each lens used. All of the images were shot at f/5.6. For some of the faster shutter speeds we did have to push the ISO up a bit, but the vast majority of the test images were shot at ISO 200.

With IS on at 24mm, the a7 II was able to churn out usable images (images that we rated either 'Excellent' or 'Some softness'), more than 50% of the time, down to 1/3-sec, and with IS off, only down to 1/30 sec. This is approximately a 3 1/3 stop advantage at 24mm. Interpreting the data slightly differently, with IS on, the a7 II hit a 20% success rate at .8 secs. It never hit a 20% success rate with IS off, but it did hit 30% at 1/13 sec and 10 sec at a/8 sec. Assuming 1/10 sec was a 20% hit rate, that would give the a7 II a 3EV advantage at 24mm.

At 55mm the a7 II hit more than 50% usable images until 1/13 sec. Unfortunately it was not even able to maintain a 50% hit rate with IS off, even at 1/50 sec, it hit 40%. If we round that 40% up to 50%, that would give the a7 II 2 extra stops at 55mm. Likewise, with IS on the a7 II hit 20% success at 1/8 sec and with IS off it hit a 20% success rate at 1/30 sec, again giving the a7 II 2 extra stops of hand-hold-ability at 55mm.

And at 200mm, the a7 II maintained 50% or greater success rate down to 1/30 sec, with IS on, and 1/200 sec with IS off, giving it a 2 and 2/3 stop advantage. At 1/200 sec with IS off, the a7 II maintained a 60% hit rate. With IS on, it hit 90% at 1/30 sec and 40% at 1/20 sec. Assuming it would hit around 65% at 1/25 sec, that would give the a7 II exactly a 3 stop advantage.

So depending on your focal length, you can assume between 2 and 3.3 stops of hand-hold-ability.

IBIS only or IBIS with OSS?

When using an OSS lens, the a7 II lets the lens-based IS handle pitch and yaw while the sensor takes on X and Y­-axis movement as well as roll. We were curious as to how this compared against the sensor taking on all IS responsibilities, and so we put a non-OSS lens - the Sony Sonnar T* FE 55mm f/1.8 ZA - on the a7 II for another go.

At 55mm, the a7 II performed better with a non-OSS lens using just the IBIS, than it did with a combination of IBIS and OSS.

Curiously, the a7 II was able to stay above the 50% success mark down to 1/8 sec. It's not until 1/5 sec where the IS fails. Shooting with the 24-70mm f/4 OSS, the a7 II was able to keep a 50% or greater success rate down to only 1/13 sec. This equates to an extra .6EV advantage using the 55mm f/1.8 over the 24-70mm f/4 OSS. So does this mean that IBIS-only outperforms IBIS coupled with OSS? Not necessarily. The 55mm f/1.8 is a much smaller lighter lens than the 24-70mm f/4, making it easier to handle, and potentially easier to hold steady. It's also possible that the lens-based IS in the 24-70 FE just isn't that great, or as good as what IBIS provides.

How Does it compare to other cameras?

Simply put, the IS system in the a7 II is very good. But how does it compare? For now, it's one of only two full frame stabilized cameras on the market, the other being the Sony a99. We haven't had the chance to test the a99 with the same protocol we used for the a7, but we have tested the Olympus OM-D E-M5 II using the same test. It's IS system scored between 2.3 and 3 stops of hand-hold-ability, quite similar to the results we found with the Sony, except with a much smaller sensor.