If there's one thing that you can say about Sony's digital camera business, it's that they've experimented with many different concepts. From SLRs with dual autofocus systems and Translucent Mirror Technology to its NEX mirrorless line-up, Sony has gone down virtually every avenue in digital imaging. Its latest products - the Alpha 7 and Alpha 7R - may be the most exciting products to come out of the Sony labs in some time. The company has managed to create full-frame cameras which are about the same size as the Olympus OM-D E-M1. In other words, the Alpha 7s are much smaller than their full-frame interchangeable lens peers (such as Nikon's D610 and the Canon EOS 6D), an achievement made possible primarily because they're not SLRs.

In addition, Sony is also unifying the Alpha and NEX brands, so all future interchangeable lens cameras will now fall under the Alpha umbrella. Being mirrorless, the a7 would have otherwise likely been prefixed with the letters NEX.

The a7 and a7R are identical in terms of physical design, with the main differences being the sensor and autofocus system. The a7 features a full-frame 24 megapixel CMOS, while the a7R has a 36 megapixel CMOS sensor with no optical low-pass filter. The a7 uses a Hybrid AF system (with on-chip phase detection) similar to the one found on the NEX-6, while the a7R has traditional contrast detection. The a7 is also capable of electronic first curtain mode, which allows for a quieter shutter, and reduces the potential for 'shutter shock' vibration; this is absent from the A7R. Both cameras use Sony's latest Bionz X processor and also have XGA electronic viewfinders, tilting LCDs, Wi-Fi, and weatherproof bodies that resemble that of the Olympus E-M1.

As you'd expect, Sony had to come up with new lenses to take advantage of the full-frame sensors, and they'll be known as 'FE-series'. Five lenses were announced to start with (listed below), with ten more promised by 2015. Existing E-mount lenses will work, though the image will (necessarily) be cropped. If you have A-mount lenses laying around, those too will work, as long as you pick up either of Sony's full-frame-ready adapters (the LA-EA3 or LA-EA4).

Sony a7 key features

  • 24.3 megapixel full-frame CMOS sensor with OLPF
  • E-mount with support for FE, E, and A-mount lenses (with adapter)
  • Bionz X image processor
  • Hybrid AF system with 25 contrast-detect and 117 phase-detect points
  • Sealed alloy and composite body
  • Multi-Interface Shoe
  • 3-inch tilting LCD with 1.23 million dots (640x480, RGBW)
  • XGA (1024x768) electronic viewfinder
  • Diffraction correction technology
  • Full HD video recording at 1080/60p and 24p; uncompressed HDMI output
  • Wi-Fi with NFC capability and downloadable apps

The a7 uses a 24.3 megapixel CMOS sensor with a low-pass filter and on-chip phase detection. This 'Hybrid AF' is supposed to result in speedier AF, supporting the camera's ability to shoot at 5 fps with continuous autofocus. The more expensive a7R, on the other hand, has a 36 megapixel sensor with no optical low-pass filter and a more conventional contrast-detect AF system.

Both the a7 and a7R can record video at 1080/60p and 24p, with manual exposure control, headphone and mic ports, an audio meter, zebra pattern, XLR support (via adapter), and live, uncompressed HDMI output.

Bionz X Processor

The company's latest processor, dubbed Bionz X for reasons that presumably made sense to someone, is considerably more powerful than the previous generation, allowing what the company says is more sophisticated processing.

Sony is being a little vague on specifics but is touting the new processor as offering 'Detail Reproduction Technology' which appears to be a more subtle and sophisticated sharpening system. The company promises less apparent emphasis on edges, giving a more convincing representation of fine detail'.

Another function promised by the Bionz X processor is 'Diffraction Reduction', in which the camera's processing attempts to correct for the softness caused by diffraction as you stop a lens' aperture down. This processing is presumably aperture-dependent and sounds similar to an element of Fujifilm's Lens Modulation Optimization system (introduced on the X100S), suggesting it's something we should expect to see become more common across brands in the coming months.

Finally, Sony says the Bionz X chip offers a more advanced version of its context-sensitive, 'area-specific noise reduction', which attempts to identify whether each area of an image represents smooth tone, textured detail or subject edges and apply different amounts of noise reduction accordingly. Later in the review, we'll show you just how well this system works, and also the problems it can create.

Lenses

While the a7 has an E-mount, you'll need to use Sony's new FE-series lenses to take advantage of its full-frame sensor. Existing E-mount lenses will still physically fit, but as they're only designed for use with APS-C sensors, their image circles won't cover the entire frame properly (just like using Sony's DT lenses on full-frame Alpha mount cameras). While five FE lenses were announced at launch, they were not all available at 'press time', and the 28-70mm F3.5-5.6 OSS will only be sold as a kit lens for the a7. All of the lenses are weather-sealed, but while the zooms include optical stabilization, the primes do not.

Here are the five FE lenses that have been officially announced:

Model MSRP Availability
24-70mm F4 Carl Zeiss OSS $1199/£1049 February 2014
28-70mm F3.5-5.6 Sony OSS Kit only Now
70-200mm F4 Sony G OSS TBD TBD
35mm F2.8 Carl Zeiss $799/£699 Now
55mm F1.8 Carl Zeiss $999/£849 Now

Sony plans to have a total of fifteen FE lenses by 2015, including macro and ultra-wide models.

The first five Sony FE lenses include two standard zooms, two primes, and a tele zoom

We're slightly surprised by Sony's strategy here: it seems a bit odd to be making two different standard zooms to start with, rather than adding a wide-angle zoom. And while it's great to see a couple of primes, both look somewhat slow given their prices. The 55mm F1.8 is a bit long for a 'normal' lens too. We'd have loved to see a fast 'portrait' lens in the 85-135mm range early on, but hopefully Sony will offer one soon.

The two cameras are perfectly capable of using existing E-mount and A-mount lenses, and you have the choice as to whether the image is cropped. If you choose to crop, the resolution will drop to 10 megapixels on the a7, and the equivalent focal length will increase by 1.5X. Sony also gives you the option to not crop and use the entire sensor, though this is likely to lead to strong vignetting.

Image 1
24mm full-frame lens - APS-C Crop Off
Image 2
24mm APS-C lens - APS-C Crop Off
Image 3
24mm APS-C lens - APS-C Crop On

The camera offers three options for its APS-C crop mode - Off, Auto and On. With it switched Off, you'll see Image 1 with a full-frame lens and Image 2 if you're using an APS-C lens. With it switched to Auto mode, you'll get Image 1 or Image 3, depending on whether you're using a full-frame or an APS-C lens. And finally, with it On, you'll see Image 3, regardless of which lens type you put on the camera.

The a7R with LA-E4 A-mount adapter and 50mm F1.4 Zeiss lens

Sony's A-Mount lenses will require the use of an A- to E-mount adapter. Somewhat confusingly Sony now offers no fewer than four such adapters, which differ in their autofocus capabilities and format coverage. The LA-E1 and LA-EA3 offer contrast detect autofocus for lenses that have built-in focus motors (i.e. SAM and SSM), but only manual focus with other lenses, while the LA-EA2 and the new LA-EA4 use Sony's Translucent Mirror Technology to offer autofocus with all lenses. The LA-EA1 and LA-EA2, however, were designed for APS-C NEX cameras and will vignette strongly when used on the a7(R); the LA-EA3 and LA-EA4 are needed to give complete sensor coverage with full-frame lenses.

Adapter Full autofocus? Full-frame ready?
LA-EA1
No
No
LA-EA2
Yes
No
LA-EA3
No
Yes
LA-EA4
Yes
Yes

It's well worth noting that the a7 and a7R are able to accept a huge range of other lenses via readily-available third-party adapters, including old manual focus lenses from long-dead systems such as Minolta MD, Olympus OM, and Canon FD, as well as those from current systems such as Nikon F, Pentax K and Leica M. What's more, in principle these lenses should offer the angle of view they were originally designed to give - so a 24mm will be a true wide-angle again, for example. So if you have a cherished collection of old manual focus primes sitting a closet, the a7 may be just the camera to bring them back to life. More on that later in the review.

Kit options and pricing

The 24 megapixel Alpha 7 sells for $1699/£1299 body only and $1999/£1549 with the 28-70 F3.5-5.6 OSS lens. For those who are curious, the 36 megapixel a7R is priced at $2299/£1699 body only.

The most notable accessory for both cameras is an optional battery grip (VG-C1EM) - a first for an E-mount camera. This grip adds controls for vertical shooting and holds an additional battery, and will set you back around $300/£259.

The a7 does NOT come with an external battery charger, instead relying on internal charging over USB. USB charging is quite slow (and it makes having a spare battery on hand more difficult), so picking up the BC-VW1 or BC-TRW external chargers is probably a smart move.

Other accessories include camera cases, an off-shoe flash adapter, wired and wireless remotes, and screen protectors.