Sony A7s vs A7R vs A7 comparison: 04 Continuous shooting and battery life
Smaller raw files and a faster sensor read speed enable the new A7s to match the A7 when it comes to burst speed.
Both the Sony A7s and A7 can hit a continuous shooting speed of 2.5fps, which increases to 5fps in Speed Priority mode.
The large file sizes of the Sony A7R mean that it's capable of a continuous speed of just 1.5fps in normal shooting mode, increasing to 4fps in Speed Priority.
The Sony A7s uses the same NP-FW50 battery as the A7/R but puts in a better battery life performance.
Sony claims the A7s's battery lasts for approximately 320 shots when using the viewfinder and 380 shots with the LCD screen when shooting stills.
That's a marked improvement over the A7R and A7, which have been measured at around 270 shots (viewfinder) and 340 shots (LCD screen) according to Sony.
Disappointingly, for a camera that's so focused on film-making, the Sony A7s doesn't see quite the battery performance boost when it comes to continuous movie recording.
According to Sony, the A7s offers approximately 90 minutes of continuous recording - that's the same as the A7R and 10 minutes less than the A7.
It's a given that you'll need a bag of spare batteries if you plan on doing day-long video shoots with the A7s.
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Sony A7s vs A7R vs A7 comparison: 05 Autofocus and metering
One of the problems of the A7R is its comparatively slow contrast-detection autofocus - it's not a camera for high-speed action.
The more 'general purpose' Sony A7 offers an improved autofocus performance, as it uses a a hybrid autofocus system which combines both phase-detection AF (for speed) and contrast-detection AF (for accuracy).
Like the Sony A7R, the A7s features contrast-detection only, with 25 AF points.
However, its low-light AF performance is improved: according to Sony, the A7s can focus from EV-4 to EV20 (at ISO 100 with an f/2.0 lens attached).
The A7 and A7R can autofocus within a sensitivity range of EV0 to EV20 (ISO 100, f/2.8 lens).
When you develop a camera that enables photographers to shoot in near-darkness with an ISO 409,600, you need to make sure that camera can focus with little available light too; the A7s has the potential to offer useable autofocus in moonlight.
Exposure metering follows a similar pattern, with all three A7 cameras using a 1200-zone evaluative metering system.
But while the metering sensitivity of the A7 and A7R runs from EV0 to EV20 (ISO 100, f/2.8 lens), the A7s extends that to EV-3 to EV 20 (ISO 100, f/2.0 lens).
On paper at least, the Sony A7s appears to be the camera of choice for low-light photography.
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Sony A7s vs A7R vs A7 comparison: 06 Price
There's still no official Sony A7s price yet, but, with camera manufacturers adding a premium for high-end video features - they have to make up for the slow down of compact camera sales, after all - we expect this to be the most expensive model in the A7 line so far.
On the Sony A7s specifications website, Sony refers to the camera in two instances as the 'Diamond' - clearly a working title that's slipped through - which gives an indication of the value they place on the A7s.
The official price for the Sony A7R is £1,699, while Sony recommends a price of £1299 for the A7.
The Sony A7R street price is no different, while the A7 can be found for just a fraction under the official price.
We anticipate a Sony A7s price to be in the region of £1,700-£1,900.
PAGE 1 - Sony A7s vs A7R vs A7 comparison: Sensor resolution, ISO; Video; Design
PAGE 2 - Sony A7s vs A7R vs A7 comparison: Continuous shooting, battery life; AF, metering; Price
PAGE 3 - Sony A7s vs A7R vs A7 comparison: our conclusion
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