The A7 and the A7r redefined compact full-featured digital photography. The new Sony A7s is about to redefine 4k video and low-light performance. Compact mirrorless cameras are accomplishing impressive feats and demonstrating that you don’t need a pro-level DSLR to produce high quality images.

The Sony A7s takes the small mirrorless form factor to the next level. This camera doesn’t just have awesome high ISO performance—it can see in the dark.

Image Sensor

Sony reconfigured their full-frame image sensor. It’s only 12.2 megapixels, much smaller than the A7 and A7R sensors. My guess is that only “pixel peepers” who create massive image enlargements will notice the difference in still shooting. The A7 boasts 24.3 megapixels and the A7R has a 36.4 megapixel sensor. Why did Sony go smaller?

Sony reduced sensor resolution to improve low-light performance and provide optimum video-shooting capabilities. More isn’t always more, especially when it comes to video and low light work. Lower sensor resolution keeps processor time fast enough to make 4k video shooting possible. Larger image sensors require more processing capabilities. In this case, a higher resolution processor would have required a much more expensive processor that would generate enough heat to make the camera inoperable at its tiny size.

There are still enough pixels for professional quality images and more than enough for professional video shooting. The minimum for shooting video in Ultra High Definition (3840×2160) is 9.3-megapixels. Full cinema 4k (4096×2460) requires 8.8 megapixels.

ISO Performance

The lower resolution image sensor was also redesigned with several dynamic range performance adjustments. Together with the full-frame sensor and larger pixels, the Sony A7s promises to be an impressive low-light performer. The ISO sensitivity ranges from 100 to 102,400 for stills and 200 to 102,400 for video. It is expandable up to ISO 409,600.

Recently, we’ve seen similar ISO numbers from Nikon’s flagship D4s, which is an excellent low-light camera. Sony, however, promises to do it better. Larger pixels, redesigned dynamic range, and the ability to adjust dynamic range to suit the shooting environment – a feature that Sony acknowledged but didn’t release much detail on – should provide comparable if not better high ISO performance with limited or no digital noise.

Video Capabilities

The most impressive feature of the Sony A7s is the ability to shoot 4k video at a near 1.1x crop. Even the Canon EOS-1D C has a 1.3x sensor crop for 4k video shooting. This is awesome for getting the most out of your lenses, improving wide-angle shooting and depth of field provided by a full-frame sensor.

There are some drawbacks. The A7s can’t record 4k video internally. You have to attach an external hard drive via HDMI to record 4k video – even when you are shooting at lower bitrates. This where a camera like the Panasonic Lumix DMC-GH4 has a big advantage. Not only does the Panasonic get the edge on the A7s with internal 4k video recording, but it also can shoot at 10-bit 4:2:2 compared to the 8-bit capabilities of the A7s.

The Sony A7s is still great for Full HD resolution (1920×1080) shooting. It can record at 60p, 60i, 30p, and 24p and you don’t need any external storage to do it. One cool feature is the ability to switch to APS-C sensor mode – it crops the sensor and allows 120 frames per second 720p video capture.

Additional Features

Beyond impeccable low-light performance, the A7s matches many of the still shooting features of the Sony A7. It can shoot 5 fps and 2.5 fps allowing for autofocus adjustments. The battery should last around 320 shots with the 2.4 million dot OLED electronic viewfinder active.

Autofocus performance doesn’t match the A7. While the A7 had an impressive hybrid AF system that utilized 25 area contrast detect and a 117-point phase detect system, the A7S only has 25 area contrast points. The lack of the hybrid system will definitely make the A7s worse than the A7 when it comes to autofocus.

Conclusion

Unless you are keen to try out the low-light performance of the A7s, the Sony A7 is going to remain the best compact mirrorless choice for still shooters in Sony’s lineup. The A7s is all about video. It’s small, full-featured, and impressive. Don’t be fooled by the smaller resolution image sensor. It’s actually good to see companies moving away from the megapixel wars. The new battle will be on low-light performance and video capabilities – the two areas where the Sony A7s shines.

Exact pricing on this compact low-light 4k video-shooting machine is not available at the time of writing this article. The price will likely be above $2,100 though. With the need to have an external HD to record 4k video, the Sony A7s will be a video shooter for professionals and consumers with deep pockets.

The Sony A7s is available now via Amazon!

Additional A7s Images