Sony's A7s matches full-frame with 4K
Sony's announced its first 4K-video-capable still camera, a surprisingly big reveal for the low-profile National Association of Broadcasters' show. Based on the same body as the A7 and A7R, but once again with completely different insides, the A7S incorporates a lower-resolution -- but still full-frame -- 12-megapixel sensor.
That's a perfect resolution for a camera like this. It's enough pixels for lots of pro work but few enough to keep a broad tonal range and fast sensor readout, which will minimize lag and processing overhead when shooting video. Ultra High Definition/Quad Full HD (3,840x2,160 pixels) requires a minimum of 8.3-megapixel resolution, while full cinema 4K (4,096x2,160 pixels) needs 8.8 megapixels.
Unlike the Panasonic Lumix DMC-GH4, however, the camera can't do any 4K internally, even at lower frame- or bitrates; you've got to rig up an external hard drive and do it via HDMI. And, disappointingly, it only does 8-bit 4:2:2 capture, compared to the GH4's 10-bit. That said, it should have a far better tonal range than the GH4 because of the larger sensor.
And while the potential dynamic range sounds great for still photographers, it has the A7R's wimpy contrast AF system. Sony hasn't yet mentioned pricing, but I suspect that it's destined to sit above the A7R in the product line, which would put the price north of $2,300 (£1,390).
Sony also announced that it has an XLR mic kit and 28-135 f4 FE-mount lens under development.
For your comparative enjoyment:
Canon EOS 70D | Panasonic Lumix DMC-GH4 | Sony Alpha ILCE-7 (A7) | Sony Alpha ILCE-7s (A7s) | |
Sensor (effective resolution) | 20.2MP CMOS n/a |
16.1MP Live MOS 12 bits |
24.3MP Exmor CMOS 14 bits |
12.2MP Exmor CMOS 14 bits |
Sensor size | 22.5 x 15mm | 17.3mm x 13mm | 35.8 x 23.9mm | 35.8 x 23.9mm |
Focal- length multiplier | 1.6x | 2.0x | 1.0x | 1.0x |
Sensitivity range | ISO 100 - ISO 12800/ 25600 (exp) | ISO 100 (exp)/ 200 - ISO 25600 | ISO 50 (exp)/ ISO 100 - ISO 25600 |
ISO 50 (exp)/ ISO 100 - ISO 102400/ ISO 409600 (exp) |
Burst shooting | 7fps 16 raw/65 JPEG |
7fps 40 raw/100 JPEG (12fps with fixed focus; 40fps with electronic shutter) |
2.5fps (5fps with fixed exposure and focus) | 2.5fps (5fps with fixed exposure and focus) |
Viewfinder | 98% coverage 0.95x/0.59x |
OLED EVF n/a-inch 2.36 million dots 100% coverage 1.34x/0.67x |
OLED EVF 0.5-inch 2.4 million dots 100% coverage 0.71x |
OLED EVF 0.5-inch 2.4 million dots 100% coverage 0.71x |
Autofocus | Dual Pixel CMOS 19-pt phase-detection AF all cross-type; center cross to f2.8 |
49-area contrast AF; DFD | Hybrid AF system 25-area contrast AF; 117-pt phase- detection |
25-area contrast AF |
AF sensitivity range | -0.5 to 18 EV | -4 to 18 EV | 0 - 20 EV | -4 - 20 EV |
Shutter speed | 1/8,000 to 30 secs; bulb; 1/250 x-sync | 60-1/8,000 sec.; bulb to 60 minutes; 1/250 x-sync | 1/8,000 to 30 secs; bulb | 1/8,000 to 30 secs; bulb |
Shutter durability | 100,000 cycles | 200,000 cycles | n/a | n/a |
Metering | 63-zone iFCL | 1,728-zone | 1,200 zones | 1,200 zones |
Metering range | 1 to 18 EV | 0 to 18 EV | 0 - 20 EV | -3 to 20 EV |
Flash | Yes | Yes | No | No |
Wireless flash | Yes | Yes | No | No |
Image stabilization | Optical | Optical | Optical | Optical |
Best video | H.264 QuickTime MOV 1080/30p/ 25p/24p; 720/ 60p/50p | MP4/MOV 4096 x 2160/24p, 3840 x 2160/30p/25p/24p @ 100Mbps (IPB); 1080/60p/ 50p @ 200 Mbps (All I) | AVCHD 1080/60p @ 28Mbps, 1080/60i/ 24p @ 24Mbps | XAVC S UHD/30p/25p 4K via HDMI; XAVC S 1080/60p @ 50Mbps; 720/120p |
Audio | Stereo; mic input | Stereo; mic input; headphone jack Optional XLR |
Stereo; mic input; headphone jack | Stereo; mic input; headphone jack |
LCD size | 3 inches inches articulated touch screen 1.04m dots |
3-inch tilting touch-screen OLED 1.04m dots |
3 inches tilting 921,600 dots |
3 inches tilting 921,600 dots |
Wireless | Wi-Fi | Wi-Fi, NFC | Wi-Fi, NFC | Wi-Fi, NFC |
Battery life (CIPA rating) | 800 shots (210 Live View) |
500 shots (1860 mAh) |
340 shots (1080 mAh) |
360 shots (1080 mAh) |
Dimensions (WHD) | 5.5 x 4.1 x 3.1 in 139.0 x 104.3 x 78.5 mm |
5.2 x 3.7 x 3.3 in 132.9 x 93.4 x 83.9 mm |
5.0 x 3.8 x 1.9 in 126.9 x 94.4 x 48.2 mm |
5.0 x 3.8 x 1.9 in 126.9 x 94.4 x 48.2 mm |
Body operating weight | 27.2 oz 771.1 g |
19.8 oz (est) 560 g (est) |
17.2 oz 487.6 g |
17.2 oz 487.6 |
Mfr. price (body only) | $1,119.00 | $1,699.99 | $1,699.99 | tbd |
Primary kit | $1,349.00 (with 18-55mm STM lens) | n/a | $1,999.99 (with 28-70mm lens) | tbd |
Alternate kit | $1,549.00 (with 18-135mm STM lens) | n/a | n/a | tbd |
Ship date | September 2013 | May 2014 | December 2013 | June 2014 |
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