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.
PAGE 1 – Sony A7s vs A7R vs A7 comparison: 01 Sensor resolution and ISO
PAGE 2 – Sony A7s vs A7R vs A7 comparison: 02 Video
PAGE 3 – Sony A7s vs A7R vs A7 comparison: 03 Design and build quality
PAGE 4 – Sony A7s vs A7R vs A7 comparison: 04 Continuous shooting and battery life
PAGE 5 – Sony A7s vs A7R vs A7 comparison: 05 Autofocus and metering
PAGE 6 – Sony A7s vs A7R vs A7 comparison: 06 Price
PAGE 7 – Sony A7s vs A7R vs A7 comparison: our conclusion
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