Olympus E-P1 Video

Olympus E-P1 Video Recording

by Dave Etchells

Video recording in SLRs and other removable-lens digital cameras is an increasingly common and important feature, a trend the Olympus E-P1 supports. In common with its competitors, it offers the ability to use a variety of lenses for video recording, and offers greater control over depth of field than do typical camcorders or digicams. The E-P1 also brings video capability in a smaller package than any other interchangeable-lens camera, particularly when fitted with the new Micro Four Thirds 17mm f/2.8 lens Olympus announced along with the E-P1. We found the Olympus E-P1 to be a competent video platform compared to competing cameras, falling about in the middle of the range in terms of capability and features. Let's take a quick look at its overall specs, and then dive a little deeper into its features and options:

Olympus E-P1 Basic Video Specs

• 720p, 30 fps HD recording
• 480p, 30 fps SD recording
• Motion JPEG encoding, AVI file format
• Autofocus possible during recording, but we don't recommend it (highly visible/audible)
• Programmed and Aperture-Priority exposure modes available (no shutter-speed control)
• EV adjustment available prior to recording, not during
• No explicit ISO adjustment for videos
• "Art Filters" can be applied to video
• Stereo audio recording via built-in microphones, no external input
• Still + Video mode snaps still image at the end of video recording
  
  

Olympus E-P1 Video Resolutions & Recording Formats

The Olympus E-P1 records either 720p High-Definition or 640p Standard-Definition video in motion-JPEG files, using the AVI file format. Frame rate is always 30 fps, but bit rates may vary somewhat, depending on the resolution being recorded and complexity of the subject. Stereo audio is recorded as 44.1 KHz PCM data, embedded in the AVI files. Here's a run-down of the Olympus E-P1's video specs:

The Olympus E-P1 offers just two video settings, either HD (high definition), recording at a resolution of 1,280 x 720 pixels and 30 frames/second, or SD (standard definition), recording 640x480 pixels, also at 30 frames/second. Its HD mode conforms to the "720p" spec, but doesn't offer the higher-resolution "1080i" mode HD option. This may not be much of a sacrifice, as 1080i recording in digicams and SLRs often brings with it either unacceptable levels of compression artifacts when faced with even modest amounts of movement in the video frame, reduced frame rates, or both. Likewise, the E-P1's 30 fps frame rate is better than some cameras that are limited to the 24 frames/second "cinema" standard, but it doesn't reach the level of smoothness and motion-capture ability offered by models sporting 60 frames/second recording. In both frame rate and resolution, it ranks roughly in the middle of the pack of current interchangeable-lens video-capable cameras.

The Olympus E-P1 records using Motion JPEG compression, saving its files in the AVI format. This is a somewhat more computer- and edit-friendly compression technology than MPEG4 or AVCHD, but at the expense of noticeably larger files: Expect to burn about 240 megabytes of card space for each minute of HD recording, and about 120 megabytes for each minute of standard-definition video. Interestingly, while the Olympus E-P1 uses Motion JPEG compression, it does vary the compression level used, depending on the complexity of the subject or amount of motion in the frame, to result in relatively fixed bit rates. That is, the megabytes/minute of video don't vary much, regardless of whether you're filming a blank white wall or highly detailed scene with lots of change from frame to frame. On higher-capacity cards, individual files are limited to 2 gigabytes in size, corresponding to a bit over 8 minutes of HD video, or 16-17 minutes of SD.

Here are a few examples of video from the Olympus E-P1, showing typical results under daylight conditions (with one example under rather dim lighting - we hope to add more such later):

Olympus E-P1 Video-Mode Focusing

The bugaboo of video with interchangeable-lens still cameras has been (and in most cases continues to be) focusing; specifically, the lack of autofocus capability during movie recording. In this area, the Olympus E-P1 once again places about midway in the range of current models. It does permit autofocus cycles during video recording, but the AF operation will be quite evident, both visibly and audibly in your recordings. - At least with the Micro Four Thirds format lenses that Olympus currently offers: We've heard that using the "video rated" 14-140mm zoom lens that Panasonic ships with their DMC-GH1 camera greatly improves the AF behavior of the Olympus E-P1 during recording, but haven't had the opportunity to test the GH1's lens on the E-P1 ourselves.

In its Movie mode, the Olympus E-P1 by default performs an autofocus cycle if you half-press the shutter button before recording a video. Once the recording has begun, half-pressing the shutter button has no effect; fully pressing it stops the recording. The AEL/AFL button on the camera's back panel will trigger an AF cycle any time, even while a recording is in process, though, and there's also a continuous AF mode that will update the focus setting whenever the camera detects a change in the image.

With either of the Micro Four Thirds lenses Olympus offers with the E-P1, the autofocus cycle is a pretty obvious affair: The image very visibly changes size as the camera adjusts the focus back and forth, and the sound of the focus activation is quite audible on the audio track in all but the loudest surroundings. As a result, we generally tried to avoid focusing during recording.

The Olympus E-P1's focus adjustment is of the "fly by wire" type, meaning that the focus ring on the lens isn't directly coupled to the lens elements, but instead simply commands the camera to move the lens elements. What this means in practice is that you can't avoid AF noise in your soundtrack by using manual focus and making only slow adjustments: The camera moves the lens in small, discrete steps, so slow adjustment of the focus ring in MF mode only means that the steps occur less frequently, not that they're any smaller or quieter. Rather than a continuous rattle, you'll hear individual ticking noises when the focus ring is adjusted slowly. One solution to this would be to simply mount an old mechanically-coupled manual-focus lens on the E-P1 via an adapter, but for most people, the solution will be to simply avoid adjusting focus while recording.

If you're not recording audio through the camera, you might find the bobble in image size acceptable, and so it might be useful to have the camera autofocus during recording. There is a continuous-AF option available in video mode that provides for exactly this. As noted, it isn't terribly quick (at least with the kit lens), but it will for the most part keep the camera focused as the framing changes. In single-AF mode, you have the option of choosing either a single AF area, or a multi-area mode, in which the camera focuses on the closest high-contrast object in the scene. In continuous-AF mode, only the single center AF area is active.

In continuous-AF mode, the camera does a pretty good (if not infallible) job of figuring out when the scene has changed. It wasn't clear to us whether it was choosing when to run a new AF cycle based on a change in brightness, color, or (most likely) simply change in the contrast-detect focus signal itself. Some subtle changes seemed to lull it into complacency, so it sometimes let changes in subject distance get a bit ahead of it. Fairly significant changes produced an immediate and generally accurate response, but we also encountered some situations (most often under indoor lighting) where the lens could "hunt" over a fairly wide range. Overall, our strong preference was to use the single-AF mode, and just let the camera focus before the recording of each clip began.

One piece of good news relative to focusing, though: If you shoot in aperture-priority mode with the lens stopped down, depth of field when recording videos can be pretty deep indeed. If you have a lot of light to work with (eg, outdoors in bright daylight), you can stop down to f/16 or even f/22 and the lens will effectively be hyperfocal from a few feet to infinity. The lower resolution of video recording helps a lot here too: With only a third to a quarter of the linear resolution of the camera's still images, the image can be quite a bit more out of focus on the sensor than would be tolerable for still images before you'll be able to discern the softness in the resulting videos. (The lens is quite soft at f/22 for still image shooting, due to diffraction limiting, but the lower resolution of video mode again renders this somewhat moot: Videos at HD resolution will be somewhat less crisp at f/22 than at the lens' sweet spot (around f/4 at wide angle, f/8 at tele), but we'd put the results well within the "acceptable" range.)

Olympus E-P1 Video Exposure Control

Some video-capable cameras offer only fully automatic exposure in movie mode, but the Olympus E-P1 gives you a choice of either Programmed or Aperture-Priority exposure metering. You can't choose the ISO the camera uses, though, nor can you set the effective shutter speed in movie mode.

In Programmed Auto mode, the camera reports the aperture it's selected, and very much tends toward larger apertures: It'll stop down some in full sunlight, but for any lighting that's much less intense than that, it tends to shoot wide open. We personally didn't mind this at all, as for most subjects we like the shallower depth of field that comes from shooting wide open. (Although the lower resolution of video vs still images means that DOF will be a good bit deeper at any given aperture than you might expect.) Still, the lack of "live" autofocus mentioned just above meant that we did find ourselves using Aperture Priority metering sometimes when the subject distance was likely to change a fair bit during the recording of a clip.

Like most video-capable SLRs, the Olympus E-P1 lets you choose from the camera's full range of White Balance settings, including manual white balance and a "Custom" (Kelvin temperature) mode that spans an unusually wide range from 2,000 - 14,000K.

The Olympic E-P1 also offers what we think may be the first implementation of a self-timer in video mode that we've seen to date. (There may well be others, this is just the first time that we've noticed one.) The self-timer feature seems less useful for video recording than it is for still images, since you'll presumably still need to trim the end of the clip, to cut out the part where you walk back to the camera stop the recording. Still, it at will at least save you from editing the beginning of the clip, so does offer some utility.

It's not strictly an exposure control feature, but this seems as good a place as any to mention the Olympus E-P1's Movie + Still recording mode. Selected via the second Record Menu screen, this option snaps a still image at the end of each movie clip: When you press the shutter button the second time, to stop movie recording, the shutter actuates, and the camera captures a full-resolution still frame. We suppose this is could be useful at times, but in our own movies, the action is usually over by the time we're ending a clip, so that's perhaps not the ideal place to capture a still frame. Still, there are times when we'd like to have a high-resolution still image of a video subject available, and this option is much quicker than having to switch back out of Movie mode to capture one.

Olympus E-P1 Image Stabilization During Video Recording

The Olympus E-P1 incorporates Olympus' body-based image stabilization, so any lens attached to it effectively becomes an image-stabilized model. (Note, though, that when using a lens that has its own image stabilization, you have to choose either the camera's IS or that in the lens; they won't work together.) All three IS modes the E-P1 offers are also available while recording movies. The four modes are IS 1 (stabilizer on), IS 2 (horizontal panning), and IS 3 (vertical panning). As in still-capture mode, you can also set the focal length of the lens explicitly, from 8-1,000mm, for use with non-Micro Four Thirds/Four Thirds system lenses, that don't communicate their focal length to the camera.

We somewhat expected to be able to hear the operation of the IS system during video recording, but instead found it to be completely silent. (At least, we weren't able to hear any trace of it in the audio track, even in very quiet surroundings.) It worked quite well, lending a good bit of added stability to our hand-held movie recordings, particularly when the kit lens was set toward the telephoto end of its zoom range.

We did notice that the IS system produced significantly more motion artifacts when it was active than when it was not. With its 30 fps frame rate, the Olympus E-P1's "rolling shutter" artifacts (see below) generally aren't quite as noticeable as those from some cameras with slower frame rates. When the IS system is active, though, the image jiggling effect we commonly associate with the rolling shutter image capture approach becomes much more prominent with the IS system in IS 1 mode. Switching to either IS 2 or IS 3 (horizontal or vertical panning mode) seemed to help this considerably, even for camera motion in the stabilized direction.

Digital and Body-Based Stabilization: Slightly longer effective focal lengths with video IS
Perhaps explaining both its silence and its impact on rolling shutter artifacts, we also noted that video-mode IS on the E-P1 appears to involve at least some amount of digital IS, of the type that stabilizes the video image by changing how the image data is clocked from the array. The key here is that the E-P1's sensor has a lot more pixels than required to generate even its 1,280 x 720 high-definition video, let alone its 640 x 480 standard definition output. In the HD case, there are 3.15x more sensor pixels than video pixels horizontally and 4.2x more vertically. This means you can compensate for camera shake pretty precisely, simply by changing which rows or column of pixels you're reading from to construct a given video frame: If camera movement shifted the image up by (for instance) an amount corresponding to a quarter of a video pixel, just shift your data readout up one row of sensor pixels to compensate.

To get a useful amount of image stabilization with this approach, you need to leave a band of "spare" pixels around the periphery of the sensor, so you can follow the image across the sensor array without running out of pixels at one edge. This in fact is exactly what the Olympus E-P1 does when you enable image stabilization in its movie mode: It crops the image slightly, then compensates for camera shake by changing the portion of the sensor it uses for the video frame. The net result is roughly a 30% increase in effective focal length: Maximum wide angle in video mode with IS active is roughly a 36mm equivalent (18mm on the lens barrel) vs the 28mm equivalent (14mm actual focal length) in still-capture mode.

Olympus E-P1 Audio Capabilities

Audio recording in movies is optional with the Olympus E-P: Audio can be turned on or off via the Live Menu, accessible by pressing the OK button on the camera's rear panel. Audio is recorded as 16-bit, 44.1 KHz stereo PCM, which Olympus advertises as being equal to the best quality provided by any of their popular handheld audio recorders. Stereo recording is done via two microphones on the camera's front face, appearing as small black dots on either side of the Olympus logo above the lens.

The internal mics did a pretty decent job of providing a stereo effect, although the localization of sound sources wasn't as good as with a high-quality external stereo microphone. (No surprise, really, given that good stereo microphones start at around $200 for just the microphone by itself.) Per their advertising, sound fidelity was indeed quite good; voices sounded natural, and sound outdoors was recorded clearly and in considerable detail.

Our one criticism of the E-P1's sound was that there seemed to be a bit more background noise in its audio tracks than we've noticed on some other cameras we've tested. There's no manual volume or input level control, so audio levels are set entirely automatically by the camera. (This is quite typical of video-capable SLRs that also record audio.) The combination of the auto-gain circuitry and the camera's somewhat "bright" sound quality tended to emphasize background noise, though, particularly in the upper midrange of the frequency spectrum. The result was a tendency toward noticeable hiss in the background of the E-P1's audio tracks. Also, the sensitivity to nearby background noises tended to limit the amount of gain increase when responding to reduced subject volume, so distant subjects were generally more difficult to hear clearly than closer ones. (This obviously will always be the case, what we're trying to say here is that the audibility of subjects fell off more rapidly with distance than we sometimes expected.) Ultimately the camera recorded any audio we were interested in hearing, but the hiss was more prominent than we'd have liked, and it would be nice if the mics' response pattern better suppressed sounds from behind and around the camera, favoring sound from in front of the camera more strongly.

In common with most other built-in mics on SLR-style cameras, the Olympus E-P1's internal mics were also very sensitive to hand movements on the body and operating noise from the camera itself. We mentioned the noise associated with focusing of the kit lens above, and found that adjustments of the zoom setting could also be heard in the audio track in quiet surroundings. A less-obvious source of noise were the little D-rings (which are actually triangular) that attach the neckstrap to the body. We noticed odd clicking noises in the E-P1's sound track, which we eventually traced to the D-rings clicking against the body as the strap flapped about while we were recording. We're not big fans of D-ring strap connections anyway; this gives us a new reason to dislike them. (We much prefer the rectangular body-mounted lugs used by some manufactures, that the strap passes through directly.)

Olympus E-P1 Movie Recording User Interface

The Olympus E-P1's movie mode is accessed via a separate position on the camera's mode dial, rather than being initiated from within one of the still-picture Live View modes. (The E-P1 is, of course, always in Live View mode, as there's no built-in optical viewfinder with Micro Four Thirds cameras.) There's no separate control button to start/stop movie recording: Pressing the shutter button begins recording, pressing it again stops it. Half-pressing the shutter button triggers an AF cycle without recording anything, just as in still-picture mode.

While some may find it more convenient to have a dedicated button to start/stop movie recording, we find the E-P1's use of the shutter button more intuitive. It might be nice to be able to initiate movie recording from any still-capture mode, but the flip side of that convenience would be a more cluttered on-screen information display when shooting still images (to accommodate information appropriate to only video recording), and a more complex Live Menu structure (already quite crowded in still-image mode). At least within the context of the Olympus E-P1's other controls, we prefer having movie mode as a separate mode dial option.

Setting adjustments in movie mode are made via a Live Menu, which appears down the right side of the LCD when you press the OK button on the camera's back. Options on the Live Menu for video recording are:

Olympus E-P1 Video Quality and Artifacts

The Olympus E-P1's video is of decent quality, although we felt that it clipped highlights more than some cameras we've evaluated. Thanks to its combination of 720p / 30 frame/second recording rate (and hence more modest data-rate requirements than some cameras offering 1080i HD modes) and its use of Motion JPEG for its file compression, it managed to hold good detail, even in the face of relatively rapid camera panning and/or high levels of subject detail. That said, though, there was also more motion blur present under bright daylight than we might have expected: While the frame rate is 30fps, some cameras can use a higher "shutter speed" for each frame, meaning the individual frames will be sharper when there's more light available. Here are some crops from one of our standard Charlotte/Frisbee clips:

As noted, the crops above show that the Olympus E-P1's motion JPEG image compression doesn't suffer too much from motion-induced artifacts. Rapid panning or subject movement will still lead to significant blurring, though, due to the slow shutter speed used to expose each frame. While we didn't attempt to measure it directly, it seems that the exposure time for each frame is tied to the E-P1's 30fps frame rate. As the crops above show, motion blur can be significant, even when shooting in bright sunlight. (That said, this is also a pretty severe test, with a fast-moving subject relatively close to the camera, and much more rapid panning than you'd ever use with most subjects.)

Rolling Shutter Artifacts

Essentially every video capable DSLR exhibits motion-related distortions called rolling shutter artifacts. These are caused because the image data is captured and then read off the chip sequentially by rows, rather being captured all at once. In the case of the Olympus E-P1, with its 30fps frame rate, this means that image data for the last row of a given frame was captured and read out about 1/30 second after the data for the top row was captured. The effect on moving objects is similar to 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.

The shots below show some screen grabs from our evaluation of the Olympus E-P1's rolling shutter behavior.

With its image stabilization system left off, the Olympus E-P1's rolling shutter artifacts seemed fairly modest relative to those of other cameras we've tested. Its 30fps frame rate is higher than the 24fps or 20fps of some competing models when shooting at HD resolutions, so its corresponding motion artifacts aren't as bad, either. As we mentioned in the section on image stabilization above, though, turning on IS made the rolling shutter artifacts much more obtrusive. The thumbnails above show examples with IS off and in IS1 mode; we found the artifacts in IS2 or IS3 modes noticeably reduced below the levels we saw with IS1, but still elevated above what we saw with IS off entirely.

The impact on rolling shutter artifacts does represent a limitation for the E-P1's IS system, but we don't want to give the impression that we don't feel that the IS system is a net negative for video. Quite the contrary: In those situations where you're trying to hold the camera steady, the Olympus E-P1's image stabilization system is very effective, to the point that we'd probably leave it enabled for most of our video shooting.

Olympus E-P1 In-Camera Image Adjustment for Movies

Olympus has for some time now made a big deal of their Art Filters in marketing their DSLRs. We know people that like these effects a lot, but confess that we've personally never found them very compelling. With the E-P1, Olympus has carried the full set of Art Filters over into Movie Mode, so those users who are into such things can take advantage of the same effects in their videos.

As usual, though, there's no free lunch, and the processing required for some of the Art Filter effects can significantly slow the frame rates. Here's a summary of what we found when shooting video using the various Art Filter effects:

As the above table shows, the only time that the actual frame rate changed in the movie file itself was with the Pin Hole filter in HD mode. For the Soft Focus and Grainy Film modes, the frame rate in the AVI file remained at 30 frames/second, but the apparent frame rate (based on the visual jerkiness of motion in the scene) dropped noticeably. In the case of Soft Focus, the drop in apparent frame rate was pretty significant. The three other filters (Pop Art, Pale & Light Color, and Light Tone), had no apparent impact on frame rate.

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 Motion JPEG image compression used by the Olympus E-P1 is one of the less compute-intensive formats, though, and its 1,280 x 720 resolution means there's a good bit less data in each frame to deal with than in videos with 1,920 x 1,080 resolution. The net result is that you should have no problem playing video files from the E-P1 on your computer, as long as it's a relatively recent and reasonably powerful model. We don't have a specific benchmark for this, but if your computer is less than 3 years or so old, it should have no problem with the E-P1's video streams. (By contrast, to play AVCHD or other keyframe-encoded video formats at full 1,920 x 1,080 resolution can demand a very powerful CPU and video card, to keep up.)

Olympus E-P1 Video Mode: The Bottom Line

Overall, the Olympus E-P1's video mode worked pretty well: It wasn't the most capable that we've tested to date, but neither was it the least. It should be reasonably competent at handling the bulk of the movie recording most consumers will care about, further enhancing the E-P1's appeal as a compact SLR-grade camera for travel and day to day portability: For the vast majority of consumers, it will eliminate the need to lug along a digicam, just for the sake of capturing video snapshots.