Sony A7 Field Test Part I
Sony A7 Field Test Part I
Initial thoughts, performance and quirks
By David Schloss | Posted: 03/07/2014
The Sony A7 and its sibling the A7R (which we've also reviewed) together mark a pivotal moment in the photographic world. Though at first glance it looks for all the world like a particularly nice fixed-lens camera, the A7 is in fact a full-frame, interchangeable-lens mirrorless cam. Its semi-pro grade body fires a shot across the bow of Nikon and Canon, both of which have taken a more cautious approach to mirrorless than some of their customers would have liked.
A more versatile option. At first glance the Sony A7 might not seem like a game changer, but it most certainly is. The camera pairs a 24-megapixel, full-frame image sensor and phase detection technology to create a camera that, in my opinion, is more versatile and groundbreaking than the higher-res (but slower-focusing) Sony A7R.
In my Sony A7R review, I noted that camera to be perfect for portraits and relatively-slow-moving subjects. It's great for wedding photographers, event photographers and enthusiasts photographing the occasional little league game. With its phase-detection autofocus capability and emphasis on greater performance, the A7 tries to capture a wider market.
It's pretty successful, although it doesn't have the performance of a professional-grade camera. It's more akin to a Canon 6D than it is to the flagship EOS 1D X, but for many users that's more than sufficient. While it would be nice to have the extra resolution of the A7R, it's more important to have a camera that can keep up with your subjects -- and the A7 can do so more often than its higher-priced sibling.
Reasonably swift burst shooting. In its fastest drive mode with focus locked, the Sony A7 will shoot at five frames per second for, effectively, as long as you like at full resolution. With my 60MB/second Lexar UHS-I flash card, I managed 75 frames before the capture rate slowed somewhat, but as with most cameras, reviewing those images is an asynchronous function -- I had to wait for the entire buffer to write to the flash card before I could review even the first image in the burst.
Nor could I access the main menu system until the buffer had cleared, and although the Function menu could be accessed, most options were greyed out. Only metering mode, focus area, DRO mode, and Creative Style could be adjusted before the buffer was empty. But on the plus side, if there was space remaining in the buffer, I could start shooting again straight away -- so I wasn't missing shots unless I needed to change camera settings before continuing.
More sophisticated autofocus. The topic of phase detection autofocus versus contrast detection is a bit technical, but it's worth knowing how it works, because it's directly related to one of the key differences between the Sony A7 and A7R.
In years gone by, conventional wisdom had it that contrast detection -- while more accurate -- was much slower than phase detection. With powerful modern processors and aggressive algorithm development, though, contrast detection has now reached performance parity -- at least, for some brands. There are still areas where each system has advantages or disadvantages.
How it works. Contrast detection works by calculating the level of contrast at the autofocus point location, then adjusting focus slightly and repeating the process. If contrast increases, you know you're heading towards correct focus; if it decreases, you're going in the wrong direction.
Phase-detection systems superimpose two images seen from opposite sides of the lens. If they overlap, then the subject is in focus. If not, then you can tell both the distance and direction to focus from the mismatch in phase between the images. That's important, because it means that there's no need to hunt around the point of focus to determine precisely where it lies.
The A7's photos couple great detail with pleasing color, good auto white balance, and spot-on exposure at default settings, most of the time. This scene is exactly as I remember it in person. This particular image was shot with the Zeiss 35mm f/2.8 lens.
This ability to determine the distance and direction of the point of focus means that phase-detection systems can track moving subjects more easily, making them better suited to shooting moving subjects. In an SLR camera, phase detection is performed with a separate, dedicated autofocus sensor. In a mirrorless camera, it's performed using the image sensor itself.
The best of both worlds. Sony's Hybrid autofocus system in the A7 uses both phase-detection and contrast-detection together for subjects located towards the center of the frame. The PDAF system provides the camera with information about the distance and direction to focus, while the CDAF system fine-tunes for maximum precision. Nearer the edges, only contrast detection is used. The result, when compared to the CDAF-only system in the A7R, is more confident and quicker autofocus, with less focus hunting.
The A7 shares the same autofocus settings as the A7R, plus one addition: an on/off menu item rather confusingly named "Phase Detect. Area". This doesn't enable or disable phase detection, but rather controls an optional overlay on the live view showing the outer limits of the phase detection area.
High ISO shots show plenty of detail, too. In this image at ISO 6400, you can clearly make out striping from the pixels on the in-focus portion of the monitor.
Not the fastest, but better than the A7R. I set the A7 to continuous autofocus and continuous shooting, then enabled the phase-detection area display so I could see where to frame my subject, and was able to capture a fast moving subject at a little under three frames per second for as long as I held down the shutter button.
Admittedly, that's a bit sedate in terms of performance, but the camera continued to focus on my subject just fine as it moved around the frame. (And by way of contrast, the A7R manages a rather lethargic sub-2 fps.)
The electronic viewfinder wasn't completely able to keep up with the action of the subject, stuttering a bit as it tried to display between shots, and blacking out between frames for longer than I'd like, but it still managed to maintain focus.
Great viewfinder. I'm a big fan of the Sony A7's electronic viewfinder, which makes EVFs of old seem like looking at video from the moon landing. It has plenty of resolution, and I think in many ways it's more useful than an optical viewfinder. Seeing a real-time histogram, for example, is impossible with a TTL optical viewfinder.
That's not to say its perfect. I felt that I had to increase the brightness in order to give me more visible detail for focus confirmation, at the expense of a slightly less accurate preview of exposure. But putting that aside, the EVF on the A7 is the most vibrant I've tried, and it's a pleasure to use. It's my belief that we're now only a generation or two away from the point at which the EVF/OVF debate is settled once and for all.
Tilting monitor. The rear-panel LCD screen is just as vibrant as the EVF, albeit with a lower resolution. Because the viewfinder is so good, I only used the LCD screen for playback, navigating menus, and for occasional over-the-head or waist-level shots. It's clear and bright even in outdoor, sunny-weather shooting, and isn't unusually fingerprint-prone.
The LCD monitor is articulated, but since it's not a tilt/swivel design it's useful only for landscape shots, and not those in portrait orientation. I must admit that I'd have preferred a tilt-swivel screen, but only if it could be installed without significantly increasing the depth of the camera.
No touch? No problem. I've become so accustomed to testing cameras with touch-screen displays that I usually find non-touch screens a step backwards in usability, but thanks to its great (and very configurable) physical controls and mostly well-considered menu system, this isn't such an issue with the A7.
One of reasons I typically prefer a touch-screen interface over a non-interactive panel is that many cameras force you to dig down through multiple menu levels to change settings, but the A7 negates the need for most of this with a smart user interface. For example, when in the AF Area menu, the vertical arrow buttons change focus mode, but you can also cycle through the different AF point sizes for the Flexible Spot setting with the left and right arrows. In some cameras, there would be an extra layer in the menu for the latter, or it would be accessed via a separate menu item.
The physical controls help out, too. To adjust sensitivity, many cameras first require that you press an ISO button to toggle ISO control with a dial or buttons, or even send you running to the menu system. The A7 instead allows for ISO adjustment by spinning the dial on the face of the four way rocker. (Another function can, optionally, be assigned, and some modes don't allow ISO control. Hence, a small icon on the LCD or EVF indicates what the dial currently controls.)
It takes a little while to learn these controls, though. During my review, I've shown the A7 to several friends who are professional photographers. They've all been impressed, but they've also all asked "Why can't I change the sensitivity without using the menu," because they didn't know about this dial's hidden purpose.
Occasionally illogical. The menu system is fairly straightforward, but its organization isn't always the greatest. For example, I'd expect to find the Format option on the first or last page of the setup menu, but it's actually on the fifth of six pages. And the seven options related to focusing are scattered across three different tabs of the Record menu, with 11 items completely unrelated to focusing interspersed between them.
Translations are occasionally a little clumsy, as well -- for example, the recommendation to "Shoot with fitting into the face frame" when registering a new subject for face recognition.
Thankfully, the quick menu (accessible by pressing the Fn button) has direct access to the most common shooting functions, and eliminates much of the need to jump into the menu once the camera is set up.
Loud shutter. The Sony A7 has a surprisingly loud shutter, which may be an issue if you're shooting in environments where noise is frowned on, or with a skittish subject. In fact, even for street photography -- a genre for which the A7 is otherwise extremely well suited -- you're not going to sneak up on anyone with the A7, once you've tripped the shutter for the first time nearby.
One thing worth noting, though, is that the A7 has an electronic first curtain shutter function, which makes it a little better in this respect than its sibling, the A7R. Electronic first curtain can be disabled, but when active it makes the shutter sound both slightly quieter, and of significantly shorter duration.