Sony NEX-7 Video Recording

High-definition video capture has become a must-have feature in this year's interchangeable-lens cameras, and essentially all the major manufacturers now provide some form of video capture in their compact system cameras. Being positioned as Sony's flagship compact system camera, the Sony NEX-7 includes some more advanced features including full manual exposure control and standard external microphone support, along with consumer-friendly options such as full-time autofocus, and a wind noise filter.

Although it does lack audio levels control, fine-grained control over framerates, and lower-res 720p high-def capture mode that are sometimes found on competing models, the NEX-7 otherwise provides an unusually richly-featured video feature set.

Sony NEX-7 Basic Video Specs

  • 1,920 x 1,080 (Full HD), 1,440 x 1,080 (Anamorphic HD) and 640 x 480 (VGA) recording
  • MPEG-4 AVC / H.264 compression, either High Profile (AVCHD) for Full HD, or Main Profile for lower-res video
  • AVCHD recorded at 60p, 60i or 24p on NTSC models; 50p, 50i or 25p on PAL models
  • MPEG-4 1,440 x 1,080 recorded at 30p on NTSC models, 25p on PAL models; VGA is 30p regardless of region
  • Autofocus functions during movie recording, with any NEX-series lenses
  • Essentially silent autofocus and aperture operation on NEX-series lenses
  • Auto, shutter/aperture-priority or full manual exposure, set before or during recording
  • EV adjustment is available in all auto and semi-auto recording modes
  • Stereo audio recording via built-in microphones or via a standard external mic jack on the left side of the camera body
  • Compatible with a wide range of Sony Alpha-mount lenses, via an accessory adapter (Depending on adapter and lens in use, autofocus may be possible, but is likely to produce audible noise and perhaps untoward focus changes in captured video.)
  • Some scene modes carry over into video recording, adjusting parameters for color and tone to match specific subject types

Sony NEX-7 Video: Image Size, Frame Rate, and Encoding

The Sony NEX-7 records at three different video resolutions, with a choice of three frame rates and two quality levels at the higher resolution. Full HD (1,920 x 1,080 pixel) movies are recorded in AVCHD format, while lower resolutions are also recorded with MPEG-4 compression, but using the Main rather than High profile setting. Unless audio capture is disabled, AVCHD movies include Dolby Digital (AC-3) stereo audio, while MPEG-4 movies include AAC-LC stereo audio. No spec is provided for the sampling rate of the audio tracks, though video players report 48 kHz at either 256 kbps for AVCHD clips, or 128 kbps for standard MPEG-4 clips.

The table below shows the specs for various video recording options.

Sony NEX-7 Video Options
AVCHD Format (MPEG-4 AVC/H.264 High Profile, .MTS files)
Resolution
Frame Rate
Average Bit Rate

1,920 x 1,080
(16:9 aspect ratio)

NTSC: 60 fps (progressive)
PAL: 50 fps (progressive)

28 Mbps

NTSC: 60 fps (interlaced)
PAL: 50 fps (interlaced)

24 Mbps
17 Mbps

NTSC: 24 fps (progressive)
PAL: 25 fps (progressive)

24 Mbps
17 Mbps
MPEG-4 Format (MPEG-4 AVC/H.264 Main Profile, .MP4 files)

1,440 x 1,080
(16:9 aspect ratio)

NTSC: 30 fps (progressive)
PAL: 25 fps (progressive)

12 Mbps

640 x 480
(4:3 aspect ratio)

30 fps (progressive)

3 Mbps

As noted above, the Sony NEX-7 offers two video recording formats, although the choice of format is made for you, depending on whether you're shooting at Full HD, or a lower resolution. The NEX-7's Full HD video is recorded using the newer AVCHD format, which is based upon MPEG-4 AVC / H.264 High Profile compression. At 1,440 x 1,080 pixels or below, the NEX-7 still uses MPEG-4 AVC / H.264 compression, but abiding by the Main Profile type. Note that 1,440 x 1,080 mode uses rectangular pixels (1.33:1), so movies are 16:9 aspect ratio. Compared to AVCHD, the vanilla MPEG-4 files are a bit less efficient in their use of memory card space for a given image quality level, but are more widely supported, and seem to be a bit easier for older computers to read. Continuous movie recording is limited to approximately 29 minutes regardless of file format, and maximum MP4 movie file size is 2GB. Sony recommends use of at least a Class 4 Secure Digital card, or a Memory Stick Pro Duo Mark 2 / Memory Stick PRO-HG Duo card to avoid issues with write speeds during video capture.

Here are some examples of video shot with our sample of the Sony NEX-7:

Sony NEX-7: Video Samples
1,920 x 1,080, 60fps progressive AVCHD, PS quality
View on Vimeo | Download Original
1,920 x 1,080, 60fps interlaced AVCHD, FX quality
View on Vimeo | Download Original
1,920 x 1,080, 24fps progressive AVCHD, FX quality
View on Vimeo | Download Original
1,920 x 1,080, 24fps progressive AVCHD, FH quality
View on Vimeo | Download Original
1,440 x 1,080, 30fps MPEG-4
View on Vimeo | Download Original
640 x 480, 30fps MPEG-4
View on Vimeo | Download Original
1,920 x 1,080, 60fps progressive AVCHD, PS quality
View on Vimeo | Download Original
1,920 x 1,080, 60fps interlaced AVCHD, FX quality
View on Vimeo | Download Original
1,920 x 1,080, 24fps progressive AVCHD, FX quality
View on Vimeo | Download Original
1,440 x 1,080, 30fps MPEG-4
View on Vimeo | Download Original
640 x 480, 30fps MPEG-4
View on Vimeo | Download Original

Sony NEX-7 Video-Mode Focusing

As with previous NEX-series cameras, consumer videographers will appreciate the Sony NEX-7's live autofocus during recording. Although pros and many advanced amateurs can "pull focus" (adjust the focus manually) while filming video, and indeed may well prefer to do so, considering focus to be another means of expressing their artistic vision, it's very much a learned skill, and something few people ever manage to do really well. Without live AF, consumers for the most part are reduced to only shooting subjects at a constant distance from the camera, or to having to settle for a lot of poorly-focused video. A lot of video-capable interchangeable-lens cameras are sold to consumers these days, and while having some video capability is certainly better than none, for most consumers to make full use of a video-capable camera it really needs to be able to focus on the fly.

With the NEX series, Sony's engineers had video recording in mind from the earliest stages of development. E-mount lenses use low-mass focusing elements and high-speed stepper motors to give the rapid response required for live contrast-detect focusing during video recording. (They also employ a continuously-variable aperture mechanism, to provide stepless exposure control, another key issue for video recording.)The result is a fairly competent autofocus system that should meet the demands of most consumers, especially considering the NEX-7's affordable pricing.

Sony NEX-7 Video Exposure Control

Sony NEX-7: Aperture Control / Depth-of-Field
Aperture control, adjusted from f/5.6 to f/32 during video capture
1,440 x 1,080, 30fps MPEG-4
View on Vimeo | Download Original

The Sony NEX-7 lets you record movies directly from any of its still-image exposure modes, including aperture-priority, shutter-priority, and full manual exposure modes, and unlike many competitors, it does actually provide direct control over the shutter speed, aperture, ISO, and exposure compensation settings for video recording, as appropriate to the current exposure mode. Perhaps even more unusually, it also provides these controls not only before capture starts, but actually during capture.

There are, of course, some provisos. The ISO sensitivity range is reduced to ISO 100 to 3,200 equivalents during video capture, and Auto ISO isn't available in Manual mode. The slowest available shutter speed is 1/4 second, and if a shutter speed below the video framerate is selected, this obviously has an effect on the perceived frame rate. (The actual video frame rate isn't reduced to match the shutter speed, however.) It's also worth noting that while Program Shift is available for still imaging, it isn't applicable to video capture. Also, with the built-in microphone, handling noise is clearly audible when changing any of these exposure variables, and they do cause clear shifts in image brightness if adjusted during capture. Still, the ability to quickly make adjustments to exposure settings without first having to stop video recording is pretty cool, and any unwanted portions can always be edited out of the video in post-processing, should handling noise or exposure level changes prove too objectionable.

White balance settings also carry over to video mode, as do the tone/color aspects of the camera's various scene modes.


Sony NEX-7 Movie-Mode Image Stabilization

Sony's unique among camera manufacturers, in having both body-based and lens-based image stabilization technology in their product lines. In the case of the NEX-7, image stabilization happens in the lens, so its availability will be a function of the particular lens used. Among the company's E-mount lens lineup, all of the zoom lenses offer nearly silent lens-based IS. Among the primes, only the 50mm lens offers stabilization. Using the 18-55mm kit lens, even in extremely quiet scenes, we were unable to hear any trace of the IS system in the NEX-7's captured sound track.

Sony NEX-7 Video: Audio recording

External Mic. The Sony NEX-7 can accept a standard external microphone straight out of the box, where past NEX-series models could accept only an optional, proprietary external stereo mic accessory.

The Sony NEX-7 can record audio via an internal, stereo microphone, comprised of two separate microphones located on the front panel, near the top of the camera on either side of the lens mount. (Although we don't have an objective way to test this, the greater separation compared to that of the stereo mic designs in some competing models seems like it may provide better stereo effect.) The NEX-7 also provides for recording via an external stereo microphone, attached via a standard microphone jack located under a rubber flap on the camera's left-hand side. For videographers interested in maximizing audio quality without resorting to a separate audio recorder (and switching audio tracks in post processing), that's a huge improvement from past NEX-models, which offered no standard mic connectivity, and could only accept a small, proprietary shoe-mount stereo microphone.

Sony's only published spec for the NEX-7's audio recording capability simply says "MPEG-4 AAC", so we don't officially know the sampling rate or number of bits of A/D resolution employed, although third-party MPEG players suggest a 48 KHz sample rate at either 256 kbps for AVCHD clips, or 128 kbps for MPEG-4 clips. Audio recorded with the camera's internal mic sounded exceptionally clear, but we do no tests to measure frequency response or sensitivity, so can't comment quantitatively. We noticed almost no audible hiss in audio tracks recorded with the in-camera mic, even in very quiet environments, where competing models often introduce a noticeable level of hiss. The camera's auto-gain system also did a good job of adjusting sensitivity as sound levels got louder or softer, with no evident "breathing" in transitions from high to low sound levels.

As noted above, the AF and iris-control systems on the 18-55mm kit lens were effectively silent, in that their operation couldn't be heard on the audio track, even with no background noise. Zooming the lens could produce audible noise, as could changing our handhold on the camera or using the physical controls, but these issues could likely be mitigated significantly with the external mic accessory.

As with most of its competitors, the Sony NEX-7 doesn't have any provision for manual audio level control, whether working from the internal or optional external mic. While we don't think this will be an issue for most potential NEX-7's buyers, it's perhaps something of a shame given the exceptional level of control elsewhere. It is, however, possible to disable audio capture altogether, and there's also an optional Wind Cut filter function.

Sony NEX-7 Movie Recording/Playback User Interface

The Sony NEX-7 makes movie recording very easy, as you can initiate it at any time, regardless of the mode-dial setting: Simply press the prominent Movie Record button with the red dot at its center at the top of the camera's rear panel, and the camera will start recording video.

Normally, this is where we'd list the Movie-mode menu items, but the NEX-7 has no separate movie menu. In fact, the only menu items exclusively related to video recording are the choice of file format (AVCHD or MP4), image size (1,920 x 1,080, 1,440 x 1,080, or 640 x 480 pixels), and frame rate / compression level (if recording at the higher resolution), as well as options to disable audio recording, and to enable the wind cut filter.

Playback mode on the Sony NEX-7 is decidedly odd; actually a little more so even than past NEX-series models. The NEX-7's playback is an either/or proposition, relative to stills and videos, and relative to the two video formats: If you've just shot a video and press the playback button, you'll see only movies of the same type last recorded that are stored on the card; not the still images. Likewise, if you've just shot a still image, you'll only see other stills when you hit the playback button. To switch between still, AVCHD, and MPEG-4 modes, you're expected to either navigate to an option on the Playback menu, or drop into thumbnail view and scroll over to the left, to select the correct tab on that screen. Alternatively, you can simply grab a throwaway exposure of the type you want to view, something we actually found much more convenient than either of the designers' intended methods. The playback mode works similarly on all of Sony's NEX-series models, although previously there was only one video format, and so there were only two disparate playback modes previously. Although we're now very familiar with this somewhat infuriating design, it initially caused us quite some consternation. We can only imagine the dismay many new NEX-series users must experience (if only until they read the manual), when they think their once-in-a-lifetime photos disappeared after they decided to try shooting a video.

We continue to mourn the absence of a playback option that's become increasingly common on video-capable cameras; namely the "trim" function. Whenever you record a short video clip, it's almost inevitable that you'll start earlier and keep recording longer than the action you're interested in. (If you don't do this, you're almost certainly going to miss action you're interested in.) While "padding" like this is important and necessary, we like to keep our videos concise by trimming away the extraneous material at the beginning or end of the clip after they're recorded. Many cameras support doing this in-camera these days, but the NEX-7 does not. You can certainly still import the video clips to your computer and do the trimming there, but for consumers, that's awfully cumbersome.

Rolling Shutter Artifacts ("Jello Effect")

Sony NEX-7: Rolling Shutter Artifacts
1,440 x 1,080, 30fps MPEG-4
View on Vimeo | Download Original
640 x 480, 30fps MPEG-4
View on Vimeo | Download Original

Essentially every video capable digital SLR/CSC currently on the market exhibits some level of motion-related distortion called rolling shutter artifacts. These are caused because the image data is captured and then read off the chip sequentially by rows, rather than each frame's data being captured all at once. In the case of the Sony NEX-7, this means that image data for the last row of a given frame is captured and read out anywhere from 1/24th to 1/60th second after the data for the top row was captured. The effect on moving objects is like that of a focal plane shutter in an SLR, but more pronounced, because the video frame is read out much more slowly than the slit of a focal plane shutter moves across the sensor.

For a camera that scans video frames vertically (as all do that we're aware of), rolling shutter artifacts will be most noticeable for subjects that are moving rapidly side to side, or when the camera itself is being panned horizontally. Verticals in the scene will appear tilted to the right or left, depending on the direction of camera motion. As an example, consider the case of a camera being panned from left to right, with a flagpole or other vertical object in the middle of the scene when recording for a particular frame begins: If the top of the object was centered horizontally when the first line of the video frame is acquired, by the time the last line of the frame has been captured, the bottom of the object will have shifted to somewhere left of center: As a result, the vertical object would appear to be leaning to the right.

Computer Requirements for Viewing HD Video

A typical computer these days has little trouble dealing with still images, but high-definition video can be another matter. Depending on the file format involved, it can take a pretty beefy computer to handle HD-resolution video playback without stuttering or dropping frames. The AVCHD image compression used by the Sony NEX-7 is one of the more compute-intensive formats, and its high maximum resolution of 1,920 x 1,080 pixels resolution means there's a lot of data in each frame to deal with. The net result is that you'll need a reasonably recent computer to play the NEX-7's Full HD video files smoothly, and will want a pretty powerful machine for Full HD video editing.

You can of course view your movies on a high definition TV via the HDMI output. If you're still on a standard-def TV, though, you're out of luck, as the NEX-7 doesn't offer any form of standard-def video output connectivity.

 



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