Sony A7 Review
Sony A7 Technical Info
by Mike Tomkins
Sensor. The Sony A7 is based around a 24.3-megapixel, RGB Bayer-filtered, Exmor CMOS image sensor with approximately the same dimensions as a 35mm film frame. Total resolution is 24.7-megapixels, and the design includes on-chip phase detection autofocus pixels. Sensor size is 35.8 x 23.9mm.
Processor. Output from the Sony A7's image sensor is handled by a brand-new BIONZ X-branded image processor. Compared to the previous generation, BIONZ X has improved performance. Sony also says that it has improved area-specific noise reduction, which varies noise reduction strength across the image in an attempt to yield a clean result without disturbing image detail.
BIONZ X also brings two new features. Diffraction-reducing technology combats the effects of diffraction limiting, improving detail at smaller apertures. Interestingly, the effect applied is both lens and aperture specific, and said to work even with Alpha-mount lenses shot through an adapter. It also has what Sony bills as "Detail reproduction technology", which tries to draw out finer details without creating halos in the process.
Sensitivity. The Sony A7's sensor and processor combine to yield a sensitivity range of ISO 100 to 25,600 equivalents. The lower end of this range can be expanded to encompass ISO 50. There's also an Auto ISO function, ordinarily 100 to 6400 equivalents. Upper and lower limits for this Auto ISO function can be adjusted to match the photographer's needs.
Performance. The Sony A7 isn't a camera you'll select for sports, with relatively sedate burst shooting performance. That will likely be forgiven by photographers hooked on its pairing of a huge sensor, compact body and affordable price, though. With focus and exposure locked from the first frame, you can shoot at up to 5 frames per second. With autofocus and exposure between frames, the maximum rate plunges to just 2.5fps. That's one frame per second faster for both figures than its higher-res sibling, the Sony A7R.
Lens mount. The Sony A7 still sports the company's mirrorless E-mount, but it now accepts new Sony FE full-frame lenses. Five Sony FE lenses debut alongside the camera, and Sony tells us it aims to have 10 FE lenses by the end of next year, and 15 lenses by the end of 2015. Of the currently-announced lenses, two are primes, and three are stabilized zooms.
The A7 can also accept standard E-mount lenses, and these can either be used with an APS-C crop (reducing image resolution correspondingly), or you can opt to view the full image circle and decide for yourself if vignetting and image quality outside of the APS-C image circle are acceptable.
You can also use Sony Alpha-mount lenses with an adapter, be they APS-C or full-frame. The latter are catered for with two new full-frame compatible adapters -- the LA-EA3 and LA-EA4 -- which replace both existing APS-C adapters. Although technically, the LA-EA3 isn't actually new, as it's been available for a while. It's just that until now, you could only buy it in a bundle with the full-frame NEX-VG900 camcorder.
Shake reduction. The Sony E-mount uses lens-based image stabilization, meaning that availability of stabilization is lens-specific. For the initial round of Sony FE lenses, all three zooms announced so far feature SteadyShot stabilization, while both primes don't.
Dust removal. As you'd expect on an interchangeable-lens camera, Sony has accounted for the possibility of dust on the sensor. The company is using an ultrasonic vibration system, coupled with a charge protection coating on a filter overlying the sensor.
Focus. The Sony A7, unlike its sibling the A7R, includes on-chip phase detection pixels, allowing for a hybrid autofocus system. There are a total of 117 phase-detect pixels, of which 99 are available when shooting with a Fast Hybrid autofocus-compatible APS-C lens.
The CDAF system in the A7, meanwhile, is branded as Fast Intelligent AF. It's said to offer good performance, thanks to a healthy readout rate from the sensor. The system provides a total of 25 contrast detection autofocus points, and is able to locate and prioritize an individual's eye when focusing.
It also includes the Lock-On Autofocus function first seen in the Sony A58, which tracks your subject as it passes between focus points, or strays outside of the focus point coverage area. (It's the first time this tech has been included by Sony in a camera without phase detection.)
If you prefer to focus manually, you'll find the presence of a manual focus peaking function to be a great aid for getting the point of focus just where you want it.
Viewfinder. Sony has gifted the A7 with a high-resolution XGA (that is to say, 1024 x 768 pixel) Organic LED electronic viewfinder. It's related to that seen previously in the flagship Sony A99 Translucent Mirror camera, but with further-improved optics for a better viewfinder image. (And indeed, it's among the best we've seen to date.)
LCD. On the rear panel of the Sony A7 is an articulated LCD monitor. It has a 3-inch diagonal and a 921600 dot resolution, and its articulation mechanism allows it to tilt up by 84 degrees for low / waist-level shooting, or down 45 degrees for shooting over your head.
There's a five-step manual brightness adjustment, and a Sunny Weather mode is available if you are shooting in bright conditions, where a washed-out-but-bright image is better than no image at all.
External flash. Sony hasn't included a built-in flash in the A7, doubtless in the interest of reducing size. That limits users to external strobes only, and they're attached via the top-deck Multi Interface Shoe mount. This has proprietary intelligent contacts, and can also be used to mount various non-flash accessories.
The A7 also accepts Minolta / Sony iISO strobes using an optionally-available adaptor. No strobe is bundled with the camera.
Exposure modes. The Sony A7 provides a healthy selection of exposure modes. These include Auto (both single-shot Intelligent Auto and multi-shot Superior Auto), Program, Aperture-priority, Shutter-priority, and Manual, plus Scene, Sweep Pano, and Movie. Scene-mode choises are Portrait, Landscape, Macro, Sports Action, Sunset, Night Portrait, Night Scene, Hand-held Twilight, and Anti Motion Blur.
Drive modes. Five drive modes are available: Single, continuous, speed priority continuous, self-timer, and bracketing. Speed priority continuous differs from standard continuous in that focus is locked from the first shot by default, but continuous AF can be enabled. Self-timer options are two or ten seconds.
Metering. The Sony A7 uses a 1,200 zone evaluative metering system, which like all mirrorless cameras operates on information from the image sensor. Three metering modes are available: Multi-segment, center-weighted, or Spot.
Shutter. Available shutter speeds range from 1/8000 to 30 seconds, plus a bulb shutter function. Maximum flash sync is 1/250s, and the A7 offers an electronic front curtain shutter option.
Movie capture. The Sony A7 can record Full HD (1920 x 1080 pixel) movies, with a rate of 60 progressive-scan frames, 60 interlaced fields, or 24 frames per second, using AVCHD version 2.0 compression in an MPEG-4 container. Sound is recorded with a built-in stereo mic, or via a stereo 3.5mm mic port. There's also a stereo 3.5mm headphone jack for audio monitoring, and you can display / adjust audio levels. The A7 is also compatible with Sony's optional XLR adapter, allowing XLR mics to be attached via the Multi Interface Shoe.
You can also output clean video with no overlays on the Sony A7's HDMI port.
Weather-sealing / cold-proofing. Although it doesn't provide a count for the number of seals, Sony describes the A7's magnesium-alloy body as both dust and moisture-resistant.
Connectivity. A generous range of connectivity options are provided for on the Sony A7. These include both Wi-Fi and NFC wireless communications, high-definition Type-D Micro HDMI video output, and a combined USB data / wired remote port, which Sony calls the Multi-Terminal Interface. There's also the aforementioned Multi Interface Shoe for external strobes and accessories, and 3.5mm stereo headphone / microphone jacks.
The Wi-Fi and NFC wireless connectivity is probably the most interesting. This allows you to share your full-frame images with a smart device such as phone or tablet, or even to view them wirelessly from your DLNA-compliant TV. You can also control the camera remotely via Wi-Fi using an available Android / iOS app.
The HDMI port is interesting, too, though. According to Sony, it's the first to automatically detect 4K displays, and provide a 4K ultra high-def video output when one is detected. The HDMI port is also unusual in that it can be used at the same time as the camera's LCD monitor.
Remote control. As well as the ability to control it remotely via Wi-Fi, the Sony A7 lets you trip the shutter release from an infrared remote, using a receiver in the handgrip. It can also accept Sony's Multi-Terminal Interface wired remotes in the USB port.
Power. Power comes courtesy of an 1080mAh Sony InfoLithium NP-FW50 battery pack. This is capable of providing up to 340 shots on a charge, with the LCD active. Note, though, that while it's tested to CIPA standards, the battery life figure doesn't include the typical 50% flash usage, since there is no internal flash in this camera.
If 340 shots isn't enough, you can double battery life by attaching the optional VG-C1EM vertical grip, which accepts two NP-FW50 batteries. With this in place, around 680 shots on a charge should be possible.
Storage. The Sony A7 stores images on Secure Digital cards, including the higher-capacity SDHC / SDXC types, and the higher-speed UHS-I types. Its single flash card slot can also accept Sony's proprietary Memory Stick PRO Duo cards, if you prefer.
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Note: For details, test results, and analysis of the many tests done with this camera, please click on the tabs at the beginning of the review or below.