Sony has revealed the Alpha A7S, capable of 4K video and delivering a vast ISO range of 50 to 409,600. Billed the world's first full-frame sensor camera that's capable of full pixel read-out - without any pixel binning process - for movie and 4K HDMI video output, the A7S joins the Alpha A7 and A7S as a compact, interchangeable-lens alternative to bulky DSLRs and video cameras.
At its heart is a new full-frame 35mm Exmor CMOS sensor which eschews chasing high megapixel counts in favor of boosting individual photoreceptor pixel size. As a result, the A7S has a 12.2-megapixel equivalent sensor, but with what Sony says is considerably improved low-light performance in both stills and videos.
That means a 50-409,600 ISO range (for photos; for videos it's 200-409,600) as well as a new 25-point Fast Intelligent AF system which will work in light conditions as low as EV-4. Inside there's Sony's BIONZ X processor, swift enough to push 4K video out the HDMI port - with 4:2:2 color sampling - to external displays or storage. It's worth noting that you'll need an external recorder in order to actually capture 4K resolution: on its own, the A7S can record 1080p at most.
In 35mm full-frame mode, XAVC-S Full HD video can be stored at 50Mbps, while in APS-C crop mode there's support for 120fps or 100fps in Full HD. 120fps can be played back at 1080/24p for a 5x slo-mo effect.
As for hardware, there's an XGA OLED Tru-Finder viewfinder, integrated WiFi b/g/n and NFC, and support for Sony's PlayMemories apps for smartphones and tablets. The 3-inch 921k-dot TFT display is adjustable up and down, and the whole thing measures in at 126.9 x 94.4 x 48.2 mm and weighs 489g with the battery - good for between 320 and 380 shots, depending on viewfinder/display usage - and a memory card, though with no lens.
On the topic of lenses, as well as taking advantage of existing E-mount lenses for the A7 and A7R, the A7S will debut alongside a new full-frame E-mount power zoom 28-135mm F4 lens intended for movies. Sony is also planning an XLR adapter kit for audio.
Sony isn't saying how much the new Alpha A7S will cost, but it's expected to go on sale this summer.