Sony Alpha NEX-7: Performance

December 7, 2011 by Jim Keenan Reads (6,716)
Editor's Rating

Ratings Breakdown (1-10)

    • Image/Video Quality
    • 9
    • Features
    • 9
    • Design / Ease of Use
    • 7
    • Performance
    • 10
    • Expandability
    • 8
    • Total Score:
    • 8.60
    • Rating 1 to 10, top score 10

It has a viewfinder that could be at home on a DSLR, a claimed shutter lag time that is DSLR-like, and a DSLR sized sensor and price tag. Is the NEX-7 truly a DSLR alternative? Let’s see.

Shooting Performance
The NEX-7 powers up quickly – not DSLR quick, but pretty fast. I was able to get off a first shot in about 1.5 seconds. Single shot-to-shot times were basically as quick as you could re-acquire focus and shoot after the previous shot, a distinct (and near DSLR-like) improvement over the NEX-5 I reviewed last year. Sony claims up to a 3 frame per second (fps) continuous shooting rate, as well as a speed priority rate of up to 10 fps. Speed priority calculates exposure and focus based on the first shot of the sequence, while continuous can make use of the camera’s continuous AF function.

In practice, the NEX-7 would make the 3 fps figure when facing less challenging situations – performance seemed to drop to around 2 fps when moving subjects were closing or opening distance on the camera rather than a more parallel course. Using a 16 gigabyte (gb) 95 megabyte per second (mb/sec) memory card produced 20 shot sequences before the camera buffer slowed at the 3 fps rate. The same card produced 20 shot sequences in speed priority mode as well.

Unlike many digital cameras, the NEX-7 does not display any indication that the camera is writing to the memory media following a long continuous sequence of shots. However, it allows you to continue taking photos as buffer space becomes available. If you continue to hold the shutter down when the frame rate slows as the buffer fills, the camera will continue to take single shots at slow intervals. Shoot a burst until the buffer slows and then release the shutter for a short time before depressing the shutter once again and the camera will shoot a burst for as long as it takes to fill the buffer once more – you may not get the number of shots you would with a clean buffer, but the camera will shoot at the continuous frame rate you have chosen until the partially filled buffer fills again.

AF acquisition time was a speedy 0.13 seconds in good conditions, but the camera predictably slowed noticeably in dim light. There is a focus assist lamp.

Shutter Lag (press-to-capture, pre-focused)

Camera Time (seconds)
Olympus E-P3 0.01
Nikon 1 J1 0.01
Sony NEX-7 0.01
Panasonic Lumix DMC-GF3 0.01

AF Acquisition (press-to-capture, no pre-focus)

Camera Time (seconds)
Sony NEX-7 0.13
Nikon 1 J1 0.21
Olympus E-P3 0.22
Panasonic Lumix DMC-GF3 0.22

Continuous Shooting

Camera Frames Framerate*
Sony NEX-7 20 10.0 fps
Nikon 1 J1 28 5.1 fps
Panasonic Lumix DMC-GF3 20 4.2 fps
Olympus E-P3 13 3.3 fps

*Note: Continuous shooting framerates are based on the camera’s fastest full-resolution JPEG continuous shooting mode, using the fastest media type available (300x CF, SDHC, etc.). “Frames” notes the number of captures recorded per burst before the camera stops/slows to clear the buffer.

The built-in flash features a guide number of 6 meters at ISO 100, and combined with the relatively slow kit lens maximum aperture of f/3.5 translates into a flash range of about 5.6 feet. Of course, closing the lens down from its maximum aperture will lower this range even further, while moving the ISO setting up from 100 will increase the range. Flash recycle times were quick – right around 1.25 seconds under conditions (f/22 aperture, ISO 100 and a dark subject) designed to produce a full discharge. Partial discharge times were about the same.

Sony rates the NEX-7 battery life as 400 shots. As mentioned earlier, take precautions when using the camera with the default monitor/viewfinder setup. The battery level display is helpful in that it presents an icon with bars that disappear as battery level drops along with a numerical percentage of battery life remaining. The latter readout is probably the one I would trust more – right now the icon on my camera shows three quarters battery life while the numerical display reads 53%.

The NEX-7 has an annoying playback regimen. If you hit the playback button the camera will display the last image captured and only the same type of images as your last shot. For example, let’s say you shot 20 video clips, then a single still, and hit the replay button. You’ll be taken to the still, and the still is the only image you can review via the replay button. Or say you shot 200 stills, then a single video clip. The replay button brings up the video.

All of your images are on your memory media, but the NEX-7 compartmentalizes imagery into still, MP4 and AVCHD folders and displays only the contents of the folder containing your last image via the replay button – you can go into the “view mode” submenu in the playback menu to designate folders containing the other types of imagery for playback. On most cameras the replay button allows you to access images or video in the order they were captured and I wish Sony had done the same.

Lens Performance
The 18-55mm kit lens is about average in lens speed as kit lenses go, with maximum apertures of f/3.5 and f/5.6 at wide angle and telephoto, respectively. Close focus distance is 9.8 inches. The 18-55 displayed some barrel distortion at the wide end and pincushion at telephoto. Edges and corners were a bit soft at both ends, but image quality seemed on a par with similar kit lenses on other cameras I’ve reviewed.

Sony NEX-7

The NEX-7 offers three lens compensation settings that can be found in the setup menu: chromic aberration, distortion, and shading (vignetting). Of these three, only chromic aberration and shading are on by default – you have to enable the distortion feature via internal menu. Here’s a look at our roofline shot at wide angle with and without distortion compensation enabled. The curvature produced by barrel distortion of the lens is largely removed with the feature enabled. Enabling distortion compensation may reduce the field of view slightly as part of the adjustment process, but the differential is slight and in my opinion worth the loss.

Sony NEX-7 Sample Image
Distortion Compensation On

Sony NEX-7 Sample Image
Distoriton Compensation Off

A little chromic aberration (purple fringing) was present if you looked long and hard at extreme magnifications (400x), but the lens did a very good job overall in this regard. While Sony builds stabilization into their DSLR camera bodies, the NEX series requires “optical steady shot” designated lenses to produce stabilization, and the kit lens used in this review is one such lens.

In addition to the kit lens Sony also provided a Zeiss 24mm f/1.8 prime lens, and if you don’t need the focal range provided by a zoom the Zeiss is a very nice choice. Virtually distortion free, the lens displays just the faintest hint of pincushion distortion which is corrected by enabling the lens distortion compensation feature. The lens is fairly uniformly sharp and largely chromic aberration free – you can find small spots here and there at 300-400% enlargements, but you’ll still have to look hard to do so. The Zeiss is not stabilized, but shooting at shutter speeds in the 1/40 second range or faster while hand-holding should not be a problem with proper technique. You also don’t want to use the lens hood on the Zeiss along with flash as the hood will cast a shadow on the image.

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