Sony NEX-3 Review – Video

Sony NEX-3 Video Recording

Sony has long been a dominant player in both professional and home-video recording, and many of their point & shoot digital cameras have offered HD video recording for some time now – But their SLR lineup has until now lacked this capability. Likewise, Sony has until now sat on the sidelines in the SLD (Single-Lens Direct view) camera market, being content to let Panasonic and Olympus break the new ground there.

With the announcement of the new NEX line of SLD cameras, Sony has made a bold step in two important directions, offering both their first SLD models, and their first interchangeable-lens hybrid still/video cameras at the same time.

Video capability. There is no separate video recording mode on the Sony NEX-3: Video can be initiated from any still-capture mode by pressing the video Movie button on the angled rear face of the body.

The new Sony NEX-3 is built around fundamentally new technology, employing both a new CMOS Exmor sensor ( Exmor is Sony’s trade name for their advanced sensors), as well as an all-new lens design engineered specifically for the demands of video recording. The combination of Sony’s Exmor CMOS technology and an APS-C sensor size (larger than the Four Thirds chips used in SLDs from Olympus and Panasonic) brings excellent noise characteristics at high ISOs, which in turn means better low-light recording capability than other current SLD competitors.

Note: The comments in this review are based on the NEX firmware version that was available at the time the review was written (v1.00). Sony has since released firmware update version 03, which among other improvements, adds aperture control during videos in Aperture Priority and “Background Defocus Control” modes. We unfortunately can’t go back and update reviews each time new firmware comes out, but you can view the list of improvements according to Sony in our NEX firmware update news article.

Its lack of manual control over video exposure parameters means that the Sony NEX-3 may not be a choice for serious video aficionados, but it does offer the ability to attach an external stereo microphone via the top-mounted accessory terminal. While it may not quite have the feature set required by high-end video users, its autofocus tracking during recording and its good low-light capability make it an excellent choice for consumers looking for a true all-in-one still/video camera for recording memories. (And as we’ve noted elsewhere in this review, its excellent still-image quality and low high-ISO noise make it well suited for enthusiast still photographers.)

Bottom line, if you’re looking for serious still-image quality and easy and effective video capture in the same affordable camera, the Sony NEX-3 clearly belongs on your very short list of cameras to consider. Let’s look at its video capabilities in a bit more detail:

Sony NEX-3 Basic Video Specs

• 720p (1,280 x 720), 30p (29.97 progressive frames/second) high-definition recording in MPEG-4 format, with two available compression levels
• 640 x 480, 30p (29.97 progressive frames/second) standard-definition recording in MPEG-4 format
• Autofocus functions during movie recording, with any NEX-series lenses (currently the 18-55mm and 16mm kit lenses, with an 18-200mm model coming soon)
• Essentially silent autofocus and aperture operation on NEX-series lenses
• Auto-only exposure (that is, no aperture-priority, shutter-priority, or manual exposure control)
• EV adjustment is available in all movie recording modes
• Stereo audio recording via built-in microphones or via an external mic attached to the top-mounted accessory connector (Sony accessory mic available; it’s not clear whether there will be adapters to connect standard 3.5mm phone plugs or not.)
• Much better than average video recording under low-light conditions
• Compatible a wide range of Sony Alpha-mount lenses, via an accessory adapter (Alpha-mount lenses permit only manual focus on the NEX-3, and aperture control may not work properly during video recording .)
• Some scene modes carry over into video recording, adjusting parameters for color and tone to match specific subject types

Sony NEX-3 Video: Aperture control or not?

In the early days following its announcement, there was a lot of confusion as to whether it provided any control over lens aperture during video recording, and even some Sony corporate sites were displaying incorrect information. We checked with our main technical contact for Sony imaging here in the US, who detailed for us which settings you’re able to adjust in movie mode, and which remain under the camera’s control. Here’s the definitive list, as received from Sony US:

Sony NEX-3 Video Settings

Function

Condition

AF Mode
(AF/MF/DMF)

Can preset (before recording)

Exposure Compensation

+/- 2EV in 1/3 EV increments
Adjustable during recording

White Balance

Can be preset (before recording)

Creative Style

Can be preset (before recording)

AF Area

Fixed at “Movie AF”
(Can’t preset, can’t change during recording)

AE Pattern

Fixed at multi-segment
(Can’t preset, can’t change during recording)

Exposure Control
(Aperture/Shutter Priority)

Fixed at Auto
(Can’t preset, can’t change during recording)

ISO Sensitivity

Fixed at Auto
(Can’t preset, can’t change during recording)

Scene Selection

Fixed at Standard
(Can’t preset, can’t change during recording)

Sony NEX-3 Video: Image Size, Frame Rate, and Encoding

The Sony NEX-3 records just two different video resolutions in MPEG-4 format. Audio recorded during movie capture is encoded as AAC-LC. No spec is provided for the sampling rate of the audio tracks, though video players report 48 kHz at 128 kbps.

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

Sony NEX-3 Video Options

MPEG-4 Format (.MP4 files)

Menu Designation

Resolution

Frame Rate

Card Capacity
(very approximate)

1280 x 720 Fine

1,280 x 720
(16:9 aspect ratio)

30 fps (progressive)
(29.97 fps actual)
9 Mbps

1.1 MB/second
(~30 minutes
on 2GB card)

1280 x 720 Std.

30 fps (progressive)
(29.97 fps actual)
6 Mbps

0.7 MB/second
(~47 minutes
on 2GB card)

VGA

640 x 480
(4:3 aspect ratio)

30 fps (progressive)
(29.97 fps actual)
3 Mbps

~0.4 MB/second
(~83 minutes
on 2GB card)

As noted above, the Sony NEX-3 offers only one video recording format — MPEG-4 AVC, also known as H.264. The MPEG-4 file format isn’t the most efficient in its use of memory card space for a given image quality level, but is widely supported, and doesn’t have the most strenous requirements in terms of processor power.

The NEX-3 offers a maximum movie resolution of 1,280 x 720 pixels, with choice of two compression levels, as well as a reduced resolution VGA mode with a fixed compression level. Frame rates and compression levels are as detailed in the table above. If you plan to shoot much high-definition video, you’ll definitely want to buy a really big SD card for use with your NEX-3, as HD video files take up a lot of card space. Continuous movie recording is however limited to approximately 29 minutes and maximum movie file size is 2GB. Sony recommends use of Class 4 or higher-rated Secure Digital memory cards for the NEX-3.

Here are some examples of video shot with our sample of the Sony NEX-3:

Sony NEX-3 Video Samples

MPEG-4 720p
(1,280 x 720 Fine quality)
(11.5 MB)
MPEG-4 720p
(1,280 x 720 Standard quality)
(9.4 MB)
MPEG-4 VGA
(640 x 480)
(3.5 MB)
 

Night Video, MPEG-4 720p
(1,280 x 720 Fine quality)
(14.1 MB)

The night scene above is a pretty dark shot, captured under slightly dimmer than average city street lighting. Some cameras can manage it, albeit with a fair bit of noise; some can handle it cleanly, but produce very dark videos. The Sony NEX-3 managed to get very usable detail, albeit at the cost of some noise and minor focus-hunting. Its overall performance was better than anything else anywhere near its price range, except for its sibling the NEX-5, though.

(Note: This video was shot alongside that of the NEX-5, hence the reference to Motion JPEG being the only mode available, since the NEX-5 also offers AVCHD. In place of an alternate compression type, the NEX-3 offers two compression levels when recording HD videos.)

Sony NEX-3 Video-Mode Focusing

Live autofocus during video recording has been a consumer bugaboo ever since video first appeared as a feature on SLR cameras a bit less than two years ago. It’s less of an issue than one might expect, because the lower resolution of video images results in greater effective depth of field than with high-resolution still images, but it’s still an issue for many consumers. Sure, you can often arrange the camera angles so the subject will stay in the plane of focus for the duration of a clip, but it’s not always possible to do that. You can also learn to “pull focus” while the camera is recording, moving between preset focus points manually, but doing that well requires a surprising level of skill and experience.

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 SLRs are certainly being sold to consumers these days, and having some video capability is certainly better than none, but for most consumers to make full use of a video camera, it really needs to be able to focus on the fly.

Most SLD cameras currently on the market offer at least some level of live autofocus, but very few do it well. Until now, the Panasonic GH1 was the only model with an autofocus system that was truly effective during video recording. The recent Panasonic G2 did very well, too, but wasn’t quite in the same league when operating with its kit lens as was the GH1. For its part, the Sony NEX-3’s live AF speed seems to be on par with or perhaps a bit ahead of the G2’s.

There are two requirements for live autofocus in a camera using contrast-detect focusing; namely a fast AF-determination system, and a lens with very fast and stable focus operation. In the Sony NEX cameras, the advanced Exmor image sensor and powerful Bionz image processing engine provide the focus-determination speed required for live autofocus. On the lens front, Sony’s NEX announcement included an entirely new lens mount (the E-mount) and a set of three new lenses to fit it. These new E-mount lenses are all designed with 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.) While you can mount other lenses on the NEX-3’s body via adapters, it’s important to note that you do have to use Sony’s E-mount lenses to get live AF capability. In fact, as noted above, standard A-mount lenses revert to manual focus when attached to the Sony NEX-3 via the optional mount adapter.

The result of this new technology is a pretty effective live AF system for movie recording, delivering the focus performance the average consumer needs for video recording. In our testing, focus-tracking speed seemed quite good, and for rapidly-moving subjects, any lag in focus generally caught up with them in just a fraction of a second, once they came to rest. Most problems we thought were the fault of focus tracking turned out on further analysis to be caused by the background having more contrast than our subjects did.

This brings us to our biggest complaint about the Sony NEX-3’s video-mode focusing: As we found with the NEX-5, the video AF area is just way broad. A bright or contrasty object a good ways away from the center of the frame can draw the camera’s focus away from a centrally-located but lower-contrast subject pretty easily. It turns out that video recording on the NEX-3 ignores any AF area setting you might have made in still-capture mode, always reverting to what seems to be an unusually large focus area. We don’t know exactly how large the video AF area is, but it seemed that a bright object anything more than about 15% of the frame width/height from the edges would cause the camera to shift focus to it. In our own shooting with the Sony NEX-3, we frequently found ourselves wishing we could tell it to use a specific focus area (as is easily done on the Panasonic G2), and had to be careful to keep contrasty background objects well away from the center of the frame. Also note that the Background Defocus control in iA mode has no effect when you begin video recording; aperture control is always automatic when recording movies.

There may well be technical limitations that preclude it (it takes quite a lot to get any kind of live AF to happen at video frame rates), but we’d really like to see an option for closest-subject focus priority and/or the ability to set a specific focus point the way you can in still capture mode. We think a lot of users will just assume that the center-area or flexible-spot focus selection they made in still mode will carry over to video recording, and be disappointed when that isn’t the case.

For more advanced users, manual focus during video recording is certainly an option, just as it is on many video-capable SLRs. The Sony NEX-3’s very high resolution screen makes this somewhat feasible, but without magnification, even a screen as sharp as this one doesn’t quite hold up to 1,280 x 720 video resolution: The AF system could almost always do a noticeably better job of focusing than we could manually, even when we got out a loupe and held it to the screen to compensate for our less-than-perfect eyesight. While 921K dots sounds like a ton of resolution (and it is, for a compact LCD screen), it only amounts to 640 x 480 pixels, only 1.5 times the linear resolution of a full HD image. This isn’t a specific knock against the Sony NEX-3, as there aren’t any appreciable differences between cameras in this regard; the LCD screen on the NEX-3 is as high-resolution as they come. One solution for manual focus inaccuracy is to simply stop down the lens more; alas, this isn’t possible with the NEX-3, because you have no aperture control during video recording.

The crops below are the same as used in our NEX-5 review, showing how well it did tracking the official IR mascot Charlotte, as she retrieved a frisbee. On a number of runs, we initially thought the camera was lagging behind Charlotte, but further experiments with a person as the subject revealed that the problem with Charlotte was most likely that she didn’t occupy enough of the frame, so the camera was taking its contrast-detect focus signal from the grass in the background. Bottom line, while not perfect, the Sony NEX-5’s video AF actually did very well. (Note that the crops below of individual frames are the video equivalent of extreme pixel-peeping in still images.)

Sony NEX-5 Video: Tracking Autofocus
(MP4 files, shot with the 18-55mm kit lens)
(NOTE: Samples from NEX-5 video, NEX-3 performed similarly)

I started the camera rolling after Charlotte had rounded the corner and was already heading back. None of the video here is wonderfully-sharp looking, thanks to the file compression and many areas of subtle contrast. (Which get compressed more.)

This is 15 frames into the clip (a half-second after the previous shot). While still looking soft from the compression, the camera is tracking very well. (Note the sharp individual grass blades, where they stand out against Charlotte’s shadow; the compression tends to leave high-contrast edges alone.)

Around frame 28 (a quarter-second or so following the prior shot, the camera is a bit behind Charlotte, as it hunts for focus. (Grass blades behind her are sharper than those under her feet.)

Just five frames later, though, the camera is back at proper focus. Details in Charlotte’s face are really stepped on by the compression, but note how crisp the high-contrast elements on the frisbee are.

A third of a second later (frame 53), Charlotte’s quite a bit closer to the camera, and it’s starting to lose her again. Her fur isn’t a whole lot softer than in the prior crop, but the logo is only just starting to go out of focus.

The camera had her face back in good focus again very quickly after she came to a stop. The camera and Charlotte were both still moving quite a lot, literally just a couple of frames before this one. Re-acquiring focus in just a couple of frames is pretty impressive.

The prior sequence was the best focus tracking we saw with Charlotte, obtained after I took particular care to keep her at the center of the frame. On several other runs, it seemed to be tracking behind her, but we discovered it was most likely just a matter of it focusing on the grass rather than Charlotte. We tried a human subject and found that the camera tracked perfectly.

This is about 2 seconds into the clip, and only a quarter-second or so after the crop on the left, so Chris was approaching the camera pretty rapidly at this point. We again see the overall softness from the image compression, but the logos on his shirt are about as crisp as they can get.

A bit over a third of a second (23 frames) later, the camera is still maintaining excellent focus tracking. Chris is quite close to the camera and approaching rapidly, making this a very tough AF challenge.

Another 7 frames (a bit over a tenth of a second), and Chris is now getting really close. Not surprisingly, this was about the point at which the NEX-3 finally started to lose tracking. Pretty impressive, that it could track this well!

The above shots were all cropped from MPEG-4 frames captured with the NEX-5 at 1,080 resolution (1,440 x 1,080 pixels) and are shown 1:1 on-screen. (In comparing these crops to those you might see on our site for other cameras, note that most competing models only capture at 1,280 x 720 pixels, so they’ll naturally appear a bit more crisp when viewed 1:1 like this.)

As you can see, the NEX-5 actually did a very good job of tracking motion with its live AF, provided that the subject was large enough in the frame: We initially thought it was lagging a bit when we shot Charlotte retrieving the Frisbee, the sequence above being one of the better ones we shot. Once we discovered how large its AF area is, though, it occurred to us that it might just be an issue of Charlotte not being a large enough or contrasty enough subject. The tests with Chris running toward the camera showed that the NEX-5 could indeed track very well, to very close distances. With the larger subject, there was also very little sign of it hunting back and forth to find the correct focus: It seemed to do a surprisingly good job of predicting where the proper focus point would be as the subject moved. As noted previously, we found the overly-broad video AF area and general AF dynamics to be essentially identical between the Sony NEX-3 and NEX-5.

Bottom line, the Sony NEX-3 is a very serviceable “hybrid” video/still camera. Usable autofocus tracking during video recording is hugely important for consumers, and the Sony NEX-3’s live AF worked pretty well. We’d really like to see a tighter AF area, and the ability to set specific AF points for movie recording, but the average consumer will find the NEX-3 vastly more usable than cameras that offer either manual-only focus in video mode, or that stop focusing once recording has started.

Sony NEX-3 Video Exposure Control

While the Sony NEX-3 lets you record movies directly from any of its still-image exposure modes, including aperture-priority, shutter-priority, and full manual exposure modes, the shutter speed, aperture, and ISO settings for video recording are always automatically controlled. Thus, while the camera’s menu system might suggest full PASM (programmed, aperture-priority, shutter-priority, and full manual exposure) exposure control for videos, there in fact is no direct control over aperture, shutter speed, or ISO during movie recording.

Exposure compensation adjustments made in still-capture modes do carry over into movie recording, provided that there’s enough light. (That is, if it’s too dark, boosting the EV adjustment won’t make your video any brighter.) White balance settings also carry over to video mode, as do the tone/color aspects of the camera’s various scene modes.

Shutter speed is one aspect of video exposure we’ve recently become more aware of. It turns out that slower shutter speeds tend to produce more natural-looking videos than faster ones: The motion blur associated with a slower shutter speed tends to smooth-out transitions between frames with rapidly-moving subjects: Cameras with 30fps recording, but shutter speeds 1/100 second or higher produce somewhat choppy, artificial-looking movie footage, while cameras with exposure curves biased toward shutter speeds in the 1/30 – 1/60 second range show a lot more motion blur, but the end result looks more natural to the eye. As with most of its competition, the Sony NEX-3’s video exposure curve is biased toward higher shutter speeds and the crispness they bring, but its 30 fps frame rate helps avoid some of the choppiness you’d normally see from such a fast shutter. We’d obviously like to see full user control over shutter speed and aperture in the NEX-3, but suspect those features are more likely to appear in Sony cameras aimed more at the video enthusiast in the not too distant future.

Sony NEX-3 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-3, image stabilization happens in the lens, so its availability will be a function of the particular lens used. Among the new E-mount lenses that were announced with the NEX-3 and NEX-5, the 18-55mm and 18-200mm models offer nearly silent lens-based IS, while the 16mm f/2.8 model does not. Even in dead-quiet passages in the Sony NEX-3’s video, we were unable to hear any trace of the 18-55mm lens’s IS in the sound track. (Or to hear any other aspect of lens operation, for that matter.) This was by far the most silent IS system we’ve yet found on as SLD-style camera.

Sony NEX-3 Video: Audio recording

External Mic. The Sony NEX-3’s optional external stereo mic plugs into the top-mounted accessory port also used by the flash.

Like most competing SLR/SLD cameras with video recording capability, the Sony NEX-3 can record audio via its internal microphones. The NEX-3 goes most of its competitors one better, though, in that it actually has two internal mics, providing stereo sound. It also provides for recording via an external stereo microphone, attached via the same accessory socket on the camera’s top that’s used by the bundled mini-flash. Currently, only a proprietary Sony external mic (shown above right) can be connected to this jack. We hope that Sony will eventually offer an adapter for the common 3.5mm stereo phone plug standard, but they may choose to reserve that capability for some as-yet-unannounced future NEX model aimed more specifically at video enthusiasts: People serious enough about video to think in terms of attaching external mics with 3.5mm plugs are also probably serious enough that they’d consider the NEX-3’s exposure control limitations too confining creatively.

Sony’s only published spec for the NEX-3’s audio recording capability simply says “MPEG-4 AAC-LC”, 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. Audio recorded with the camera’s internal mic sounded very clear, but we do no tests to measure frequency response or sensitivity, so can’t comment quantitatively. Hiss levels during quiet sections also seemed quite low compared to those of some competing models. We did notice that there was audible hiss in audio tracks recorded with the in-camera mic in very quiet environments, but less than we’ve heard on some competing models. 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.

We did have one significant complaint with the Sony NEX-3’s audio recording: As is the case with most video-capable SLR/SLD cameras we’ve tested, the NEX-3’s internal microphones are exquisitely sensitive to noise produced when operating the camera’s controls or even moving your hands on the body. Unique in our experience, though, is that the NEX-3 records a very audible click at the end of every clip, produced when the Movie Record button is pressed to stop recording. This seems absolutely nonsensical to us. Since you’re trying to stop the recording, why should the camera record the sound of the very button you’re using to tell it to stop? Rather than having an approximately half-second lag before the recording stops, why can’t the camera just look back in its buffer, and simply not record the last half-second of video to the memory card? It’s probably not as simple as that, and the NEX-3’s behavior in this area is probably preferable to that of the Panasonic G2, which actually stops recording the video before you press the button. Still, the inevitable “click” at the end of every recording was probably our second-biggest gripe with the Sony NEX-3’s video mode. (Second behind its over-large video-mode AF area.)

As noted above, the AF and iris-control systems on both kit lenses we tested (the 18-55mm and 16mm) were effectively silent, in that their operation couldn’t be heard on the audio track, even with no background noise. Zooming the 18-55mm lens could produce audible noise, but the amount and whether it was apparent on the audio track depended a lot on how much background noise there was, and on how fast we zoomed (slow zooming was almost never audible, except in very quiet environments).

Finally, as with all its competitors, the Sony NEX-3 doesn’t have any provision for manual audio level control, whether working from the internal or optional external mic. As is the case with the lack of a 3.5mm external jack, we don’t think this will be an issue for the NEX-3’s primary target buyers.

Sony NEX-3 Movie Recording/Playback User Interface

The Sony NEX-3 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 on the camera’s top panel, and the camera will start recording video.

Normally, this is where we’d list the Movie-mode menu items, but the NEX-3 has no separate movie menu. In fact, the only menu item exclusively related to video recording is the image size (1,280 x 720 in either Fine or Standard quality, or 640 x 480.)

Playback mode on the Sony NEX-3 is decidedly odd, although it offers at least one feature we liked. The odd part is that the NEX-3’s playback is an either/or proposition, relative to stills and videos: If you’ve just shot a video and press the playback button, you’ll see only movies 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 the two modes, you have to either navigate to an option on the Playback menu, drop into thumbnail view and scroll over to the left, to select the correct tab on that screen, or simply grab a throwaway exposure of the type you want to view. We actually found it much more convenient to hit the Movie Record button twice (to record a brief video clip) than to navigate through the playback menu to change the playback mode. This was the first time we’d ever seen a camera’s playback mode work like this, and it caused us some consternation until we figured out what was going on. “Where’d all my movies/stills go?” RTM, as they say, but we can only imagine the dismay many users will experience (if only until they read the manual) when they think all their vacation photos disappeared after they’d finally shot a video. Since so few people actually do read manuals, we also suspect this is going to be the source of a lot of service calls to Sony’s support centers.

The likely reason for this odd either/or choice for movie/still playback reveals itself when you try to scroll through movies you’ve recorded, to find a particular one you want to play back: Scrolling through recorded movies is just ineffably slow. Well, perhaps not ineffably; it’s a matter of a couple of seconds per movie, but that’s slow enough that navigating through more than two or three movies can be seriously painful. Why so slow? The camera is lightning-quick scrolling through still images, and doesn’t it save a JPEG thumbnail of each movie, for just this purpose? This is another area that’s going to produce a lot of frustration with users.

While it pales beside the slow playback scrolling, we missed one other playback option that’s become increasingly common on both digicams and SLDs; 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-3 does not. You could certainly import the video clips to your computer and do the trimming there, but that’s awfully cumbersome. Far easier to simply trim and toss away the unwanted footage on the camera. (More grist for the mill for the first firmware update to the NEX-3… 😉

Rolling Shutter Artifacts

Sony NEX-5: Rolling Shutter Artifacts

We’ve not yet shot our rolling shutter test for the NEX-3, but in the meantime, here’s the result from the closely-related NEX-5. While present, we found the Sony NEX-5’s rolling shutter artifacts to be less obtrusive than those of some of its competitors. The slanted verticals in the shot above show this effect, in response to some pretty fast shaking. (Faster than you’d be likely to pan, even following action.)

Essentially every video capable digital SLR/SLD 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-3, this means that image data for the last row of a given frame is captured and read out anywhere from 1/25th to 1/30th 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 Sony NEX-3 supports only the MPEG-4 recording format. MPEG-4 isn’t quite the most space-efficient format relative to its quality level, but is quite widely supported by computer playback and editing software. It also has the advantage that it requires somewhat less processing power than some formats such as AVCHD.

Sony NEX-3 Video Mode: The Bottom Line

Overall, the Sony NEX-3 is a great camera for consumers looking for a capable interchangeable-lens camera that can record video without the hassle of poor or no live focusing encountered with most of its competitors. We’d really like to see both a smaller AF area and the option to change its location within the frame, but with reasonable-sized and reasonably well-lit subjects, the NEX-3’s autofocus responds quickly and accurately. The near-silence of the 18-55mm kit lens’ focusing, aperture and IS operation is a big plus. When recording video, the Sony NEX-3 offers no control over exposure other than exposure compensation and white balance, but most consumer-level users won’t be looking for these capabilities. Serious video enthusiasts will likely pass over the NEX-3 unless or until more advanced exposure controls are added via a firmware update. Ditto with external audio: The Sony NEX-3’s internal stereo mics do an excellent job of recording sound, and the proprietary Sony external stereo mic will likely do ever better. Video enthusiasts will miss the option of connecting external mic systems equipped with standard 3.5mm plugs. On a positive note, though, the NEX-3 does better recording under limited- or low-light conditions than most of its competition.

At the end of the day, the Sony NEX-3’s video capabilities are a good match for its target markets: On the one hand, it’ll be amply adequate for the average consumer who wants to record video, but doesn’t want to learn learn the fine art of focus-pulling to do so. It should also be adequate for advanced still shooters drawn to the camera’s good still image quality, but who want to record occasional videos with better quality and less hassle than a second-camera digicam would provide. While the NEX-3 does trade away the NEX-5’s AVCHD recording option and the 1,080i resolution that it offers, we think most users will be entirely happy with 720p for their videos. (And the MPEG4 format is more widely supported by consumer-level video editing software than is AVCHD.) All in all, it provides a level of practical video recording that few SLRs or SLDs can equal.