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Sony A7S Preview – A low resolution marvel for low-light & video?


Sony A7 cameras are the world’s first full-frame hybrid cameras, with the recently released 12.2Mp A7S boasting 4K video output and an ISO 50-409,600 sensitivity range for stills.

Sony A7S Specification – Less pixels, better light gathering?

The evolution of Sony digital cameras certainly isn’t conservative as they continue to push boundaries on several fronts. In recent years we have seen mirrorless cameras with APS-C sensors in the NEX range, full-frame RX1 & RX1R compacts, as well as Translucent Mirror DSLRs like the SLT A77. Not satisfied with that, their latest A7 range become the world’s first mirrorless hybrid cameras built around a full-frame sensor. Six months on from the dual launch of the 24.2Mp Sony A7 and 36.4Mp Sony A7R, the new Sony A7S features a lower resolution 12.2Mp CMOS sensor, with an improved sensitivity range for stills of ISO100-102,400 (expandable to ISO50-409,600).

Sony A7S Sensor

With less pixels on the Sony A7S full-frame sensor the pixels can be physically larger to improve the camera’s light gathering capabilities. Sony go so far to say that the sensor has “extraordinary sensitivity… to collect dramatically more light than traditional cameras”. We’ll certainly be testing that as we put the Sony A7S through its paces in our lab tests in the coming weeks, but if its predecessor are anything to go by the signs are very encouraging. With an Overall Score of 95 the 36.4Mp Sony A7R ranks 2nd on our database, just behind the Nikon D800E, with the 24.3Mp A7 finishing a very respectable 9th overall and 2nd for Sony mirrorless cameras. 

Sony A7R DxOMark ranking

With Overall Scores of 95 and 90 the Sony A7R and A7 are among the best sensors we’ve tested.

Sony A7S Specification – 4K video output via HDMI

Other headline grabbing specifications are the Sony A7S’s video capabilities. Billed as the world’s first camera to use the entire full frame sensor for video capture, the A7S can output 4K video over HDMI at 30p. This means you can record 8-bit 4:2:2 4K QFHD (3840x2160px) footage to an external 3rd party 4K recorder, but not directly to a memory card. The Sony A7S will however record full HD 1080/60p video to a compatible memory card, and also offers 120fps capture at standard HD (1280x720px) when used in its APS-C crop mode. Offering great low-light shooting for movies too, the ISO ranges from 200-102,400 in video mode, there’s a tilting LCD screen for waist-level shooting, and alongside the AVCHD codex used on the Sony A7 & A7R cameras, the A7S also offers the more versatile XAVC S system with bit rates of up to 50Mbps.

Sony A7S Preview

Back to stills, the 25-point autofocus system is the same one found on the Sony A7 and A7R, there’s a built-in 2.3m dot EVF for composition, and the 3” LCD boasts a 1.2m dot resolution. Whilst there’s no built-in flash an external flash can be connected to the Sony A7S via the standard Multi Interface Hotshoe, which is the standard U shaped variety. This is a bit of an oddity, as to benefit from TTL flash using Sony flashguns with the old Minolta hot shoe, such as the HVLF 58, you’ll need to use an adapter. 

Sony A7S Preview

With the new full-frame mirrorless format a range of new FE mount lenses have been specifically designed for the A7 series. There are currently five FE lenses available, including two f/4 standard zooms, a 70-200mm f/4 telephoto zoom and a couple of fast primes – 55mm f/1.8 & 35mm f/2.8 – with more FE lenses promised in 2015. If you’re after more specialist optics however, for now you’ll have to use Sony E or A mount lenses via an adapter, and many of these won’t take advantage of the A7S’s full-frame sensor as they produce a smaller image circle designed for APS-C sensors.

Pricing and availability for the Sony A7S is still to be confirmed.

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