Sony’s press conference was all about 4K, as expected. We got our first look at the Sony A7s and, again, Sony has stepped up the game.
Instead of bumping up the resolution again, Sony has placed a full frame 12.2MP sensor inside the camera. And while the A7s can capture 4K video, it will not capture 4K video to on-board memory cards – only to an external recording device via the HDMI output. The clean HDMI output signal is 3840 × 2160 (30p/24p) or 1920 × 1080(60p/60i/24p) 4:2:2 8 bit.
Sony references no dedicated external recorder, only pointing to an “optional external 3rd party 4K recorder” as being required for 4K capture.
The Sony A7s records 1080p HD video at up to 60fps with the XAVC S codec at 50MB/s and AVCHD at 28MB/s. The XAVC S codec also allows the A7s to capture 720p video at 120fps at a 50MB/s bit rate – making it the first mirrorless or DSLR deliver 120fps video in HD resolution.
The α7S camera is also equipped with S-Log2 gamma, which expands the dynamic range by up to 1300% to minimize clipped highlights and loss of detail in shadows.
The other big feature is the sensitivity of the 12.2MP sensor. In what is most likely a side benefit of the lower resolution (and larger photosites), the A7s delivers up to ISO 409,600. To take advantage of this low-light imaging power, Sony claims that the low-light AF sensitivity that can go as low as -4EV.
Alongside the A7s, Sony also unveiled an in-development, full-frame power zoom 28-135mm f/4 lens E-mount lens for use with the A7 series.
Pricing and availability have yet to be announced for the A7s or 28-135mm f/4 power zoom lens.