Fast Focus in Low Light
If you can see it. You can shoot it. Because of the high sensitivity of it’s sensor, the Sony A7S can focus quickly and accurately in extremely low light. The A7S has a Focus Sensitivity Range of EV -4 to EV 20 (at ISO 100) which makes it a whopping 16 times more sensitive than A7/A7R which have a Focus Sensitivity range EV 0 to EV 20 (at ISO 100). EV -4 is the equivalent of the light from a single candle, but I actually found the A7S did a great job focusing in low light too dark to see with my eyes.
The Sony A7S relies on the same 25 Contrast Detection Auto Focus points found on A7R. But in extremely low light (EV -4 to EV 0) where the A7 and A7R can struggle to hit focus, the A7S CDAF is both fast and accurate.
Phase Detect Auto Focus is better at tracking moving subjects using AF-C zone focusing but Contrast Detect Auto Focus is more accurate at focusing on stationary subjects. This is why CDAF is the best choice for AF-S mode using a selective focus points. Because of the A7S senor’s extreme sensitivity, focus is both fast and accurate even in low light.
Sony A7S | FE 55mm F1.8 ZA | 1/320 | F/1.8 | ISO 3200 | CLICK TO SEE 100% CROP
Sony A7S | FE 24-70mm F4 ZA at 24mm | 1/400 | F/4.5 | ISO 3200
Sony A7S | FE 55mm F1.8 ZA | 1/400 | F/1.8 | ISO 6400
Sony A7S | FE 55mm F1.8 ZA | 1/160 | F/1.8 | ISO 6400
Sony A7S |Â Sony FE 35mm F2.8 ZA | 1/60 | F/2.8 | ISO 6400
Sony A7S |Â Sony FE 35mm F2.8 ZA | 1/400 | F/2.8 | ISO 12,800
Improved EVF Performance in Low Light
Forget about about graininess in the EVF display in low light. While the A7S EVF is physically identical to A7 and A7R, the EVF no longer needs to apply gain to in low light due to the high sensitivity of the senor ensuring the Sony A7S’s EVF rocks even in extremely low light making it Sony’s best EVF ever.
Sony A7S Camera (Amazon | B&H)
Sony A7R Camera (Amazon | B&H)
Sony FE 35mm F2.8 ZA Lens (Amazon | B&H)
Sony FE 55mm F1.8 ZA Lens (Amazon | B&H)
Sony FE 24-70mm F4 ZA Lens (Amazon | B&H)
Sony FE 70-200mm F4 G OSS Lens (Amazon | B&H)
Sony LA-EA4 Lens Mount Adapter (Amazon | B&H)
Sony SAL 70-400mm F4-5.6 G II Lens (Amazon | B&H)
Sony Sling Bag Carrying Case (Amazon | B&H)
Sony Alpha DSLR Camera/15″ Laptop Backpack (Amazon | B&H)
Sony 32GB SDHC Class 10 UHS-1 Memory Cards (Amazon | B&H)
Processed in Adobe Lightroom 5 (Amazon | B&H)
SONY A7S FIELD TEST: PART 1 – WORLD CUP FUTBOL FEVER
SONY A7S FIELD TEST: PART 2 – HIGH ISO. LOW NOISE.
SONY A7S FIELD TEST: PART 3 – HIGH DYNAMIC RANGE
SONY A7S FIELD TEST: PART 4 – FAST FOCUS IN LOW LIGHT
SONY A7S FIELD TEST: PART 5 – SILENT SHOOTING MODE
For more tips and tricks about getting the most out of your Sony a7 series camera, check out my book ‘Sony a7-Series: From Snapshots to Great Shots’. It’s your guide to all of the Sony a7 Series I & II cameras. While the camera manual explains what the camera can do, it doesn’t show how to use the camera to create great images! Starting with the Top Ten things users need to know about the cameras, author Brian Smith, a Pulitzer Prize-winning photographer and Sony Artisan of Imagery, carefully guides you through the operating features of Sony a7, a7R, a7S, a7II and a7RII and how to use them. Get practical advice from a pro on which settings to use when, great shooting tips, and assignments at end of chapter to practice what you’ve just learned.
‘Sony A7 Series: From Snapshots to Great Shots’ is available NOW from Amazon
15 thoughts on “Field Test: Sony A7S for Still Photographers – Part 4”
Thanks for the detailed and interesting review.
Thanks for the informative review.
How did you determine the DR of the A7S to be +15 stops?
DXO rated it at less than 14 stops.
Manufacturer specs. I don’t put too much weight on DxO.
Hi Brian, is there a limit to the ISO when the silent shutter is activated or can you go up to 400k?
Thanks and great review.
I’m not certain about that. I happened to test it at ISO 3200, simply because I didn’t have the need to go higher.
I had a sneaky feeling the FE 24-70 would be a better match for the A7S, especially in the corners. What were you observations Brian?
Thanks Chris, I don’t pay a lot of attention to extreme corners, so I honestly didn’t notice one way of the other.
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Great review, thanks. Canon and Nikon better innovate to keep up!
If I was to buy today, I’d probably get the A7S for what I do, but at this point too invested in a Canon 5D Mark3 to make a switch.
Hi Brian, is there a way to adapt autoficus Nikon lenses to the A7s? I heard that Commlite are making an adapter but I donno much yet
I’ve seen a few videos showing a prototype Commlite adapter auto-focusing pretty well with a Nikkor 50mm F1.4 G. How it will work with other lenses is at this point a mystery. The 50mm 1.4 has relatively small moving elements. Don’t expect the same performance from a 500mm F4. one of the easier lenses in terms The video does not show There are a couple MAJOR factors that help explain why no Nikon AF adapters have actually hit the market. It probably makes more sense to detail them in a full post rather than relegating them here. I’ll work on it.
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