Panasonic GX1 Video

Panasonic GX1 Video Recording

High-definition video capture is now a must-have feature in interchangeable-lens cameras, and essentially all the major manufacturers now provide some form of video capture in their compact system cameras. Although it's positioned as a mid-range camera, the Panasonic GX1 lacks some features of competitors such as manual control of exposure, external microphone connectivity, and the wide selection of frame-rates that a professional videographer would expect. One feature it does offer that's still relatively less common is support for Power Zoom lenses, which make it easier to adjust zoom during capture without shaking the camera, although at the current time there are only a few choices of compatible lens models. It also provides full-time autofocus--something that is arguably more important than manual exposure in a camera at this level--as well as manual audio levels control.

Still, the combination of Full HD recording and full-time autofocus will likely be plenty for those looking for an alternative to bringing a separate camcorder, but who don't need precise control over exposure. Most consumers and quite a few enthusiasts will likely count themselves in this number.

Panasonic GX1 Basic Video Specs

• Interlaced 60 fields-per-second Full HD / 1080i (1,920 x 1,080) or progressive scan 60 frames-per-second 720p (1,280 x 720) high-def recording in AVCHD format (50 fields / frames per second in PAL mode)
• Progressive-scan 30 frames-per-second Full HD / 1080p (1,920 x 1,080), 720p (1,280 x 820), or standard-def VGA (640 x 480 recording in MP4 format (25 frames per second in PAL mode)
• All videos are derived from 30 fps sensor output in NTSC mode, or 25 fps output in PAL mode (US models are NTSC-only)
• Autofocus is possible during recording, with variable results depending on the lens used (best results with 'HD'-branded lenses)
• Programmed-only exposure (that is, no true aperture-priority or shutter-priority, nor manual control), with two slight exceptions as below
• Aperture control is possible in iAuto mode, but this disables many other options such as white balance, all but standard / mono photo styles, etc.
• Flicker Reduction does let you choose shutter speeds of 1/50, 1/60, 1/100, 1/120 second, providing (very) limited shutter control. (As the name suggests, this is intended primarily for avoiding video flicker from fluorescent lights.)
• EV adjustment is available in all movie recording modes, but can't be adjusted during recording.
• Stereo audio recording via built-in microphone.
• Automatic or four-step manual audio levels control, or disable audio altogether
• Still image capture possible during video recording
  
  

Panasonic GX1 Video: Image Size, Frame Rate, and Encoding

The Panasonic GX1 records a variety of resolutions and frame rates, using either the more space-efficient AVCHD or the more broadly compatible MPEG-4 file formats. The capture rate for AVCHD movies is always 60 fields per second at 1080i or 60 frames per second at 720p in the US and 50 fields / frames per second in Europe, but note that, regardless of the capture rate, the sensor is capturing at 30 or 25 fps respectively, and the additional frames are created by interlacing or doubling the frames coming from the sensor. In MPEG-4 mode, a rate of 30 frames per second is always used, matching the sensor rate. No spec is provided for the sampling rate of the audio track during movie recording, though video players report 16-bit 48 kHz AC-3 stereo at 192 kbps for AVCHD.

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

As noted above, the Panasonic GX1 offers two video recording formats, either the HD-only AVCHD format or the less space-efficient but more widely-recognized MPEG-4 The latter format is a bit less efficient in its use of memory card space, but of the two, it's the more likely to be recognized by your computer. AVCHD is the best choice if smaller files are your main aim, but MPEG-4 offers better quality, easier editing, and wider compatibility.

In AVCHD mode, two resolutions are available, but both offer the same bit rate of 17 Mbps (megabits per second), so essentially you're trading compression level versus resolution. No lower compression levels are offered, but that's not necessarily a negative. In our experience with cameras recording in the AVCHD format, we've generally found that the video artifacts associated with quality settings below 17 Mbps generally weren't worth the savings in file size anyway. Note that Panasonic doesn't include a switchable video output mode in North American cameras, but those intended for sale in other markets may allow a choice of either NTSC or PAL video encoding. For NTSC mode, AVCHD files generated by the GX1 are always recorded at a rate of either 60 fields-per-second interlaced for 1080i, or 60 frames per second progressive-scan for 720p, but the source data provided by the sensor is read off at a rate of 30 frames per second. If a PAL mode is available, then when set to this, the 60 fields / frames per second rates are replaced with 50 fields / frames per second rates, deriving from 25 frames per second sensor data.

MPEG-4 offers a choice of three file sizes, as detailed in the table above, all recorded at 30 frames/second, with the sensor capturing data at that same rate.

Panasonic recommends use of at least a Class 4 Secure Digital card to avoid issues with write speeds during video capture.

Here are some examples of video shot with our sample of the Panasonic DMC-GX1:

Panasonic GX1 Video-Mode Focusing

As in other Lumix compact system cameras, consumers will doubtless find the Panasonic GX1's live autofocus during recording to be a very important feature. Pros and 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. Doing it well is very much a learned skill, though, and something few people ever learn 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 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.

Panasonic's engineers really had video recording in mind from the very beginning of Micro Four Thirds development. As a result, Panasonic compact system cameras have offered quite capable video-mode focusing, and the GX1 is no exception. For the most responsive video focus-tracking, you'll need a special video-specific lens, badged with "HD" video support branding. Most current Panasonic Micro Four Thirds lenses are now HD-capable, but there are still a few models that lack the quieter AF of newer models, and of course if you have older glass, this may lack the HD badge.

We continue to find that we appreciate Panasonic's touch-select movable focus point in the GX1 as much or more for video recording than we did when shooting still images. We've honestly never been particularly big fans of touch-screen interfaces on cameras, but the way Panasonic implemented theirs on the is very fluid and natural, and really makes a lot of sense. We especially liked that we could use the touch-select focus to change the point of focus in the frame while video recording was in progress, at least with the AF control set to the 23-point option: We could start with the camera focused on a foreground object on one side of the frame, and then have it transition smoothly to focusing on a background object on the other side of the frame, simply by touching the other side of the LCD screen. The advantage of this is that our finger caused no noise on the audio track, other than the operation of the focus motor itself. This is a nice contrast to systems where shifting the focus would require either manual manipulation of the lens or pressing buttons on the camera's user interface, either of which would produce clearly audible noise on the audio track. The newer Power Zoom lenses promise to make things even better, with a gentle push on two rocker control making shake- and (handling) noise-free adjustments to either focus or zoom position even easier, and allowing variable speed on both controls.

Panasonic GX1 Video Exposure Control

While the Panasonic GX1 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 controls might suggest full PASM (programmed, aperture-priority, shutter-priority, and full manual exposure) exposure control for videos, no direct control over lens aperture is available, and nor is full control over shutter speed. With that said, at least a little control is indirectly available in both areas. An option on the Motion Picture menu enables or disables Flicker Reduction, which lets you choose shutter speeds of 1/50, 1/60, 1/100, and 1/120 second for movie recording. These are intended to help in controlling video flicker caused by fluorescent lighting, but can also be used to gain at least a measure of direct control over shutter speed. Switching to iAuto mode, meanwhile, provides the ability to bias the lens aperture in your chosen direction, although this also dictates some other compromises. Specifically, if you're using iAuto mode, you're restricted to either Standard or Monochrome photo styles, and can't change any settings except picture mode, metering mode, Intelligent Resolution, Intelligent Dynamic-range Control, digital zoom, and flicker reduction.

In addition to the conventional exposure modes, the Panasonic GX1 offers many of its still-image scene modes for video recording as well. The Creative Control function is available for both stills and movies, and offers sub-options of Expressive, Retro, High Key, Low Key, Sepia, High Dynamic, Toy Effect, and Miniature Effect. This last option causes a significant reduction in capture frame rate, and rather than playing back with this same, rather jerky frame rate, videos recorded with the Miniature Effect function active will instead play back at a greatly accelerated speed with no sound. Photo Styles also apply to both stills and videos, and options here include Standard, Vivid, Natural, Monochrome, Scenery, Portrait, and a Custom option which lets you adjust Contrast, Sharpness, Saturation, and Noise Reduction levels to your liking.

Panasonic GX1 Movie-Mode Image Stabilization

Panasonic's image stabilization technology is lens-based, so IS effectiveness and impact on the audio track will depend on the lens you're using. We felt that the base kit 14-42mm lens's IS worked well, and had relatively little impact on the audio, but we could definitely hear it working in quiet passages: When recording in quiet settings, you'll probably want to turn it off, but it's still quieter than typical body-based IS systems.

Panasonic GX1 Video: Audio recording

Panasonic doesn't publish specs for the GX1's audio recording capability, but video players report 48 kHz AC-3 Dolby Digital stereo at 192 kbps for AVCHD. Audio recorded with the camera's internal mic seemed plenty clear, but we do no tests to measure frequency response or sensitivity. We did notice that there was audible hiss in audio tracks recorded with the in-camera mic in very quiet environments. On a positive note, though, we didn't hear any audible "breathing" from the auto-gain system adjusting sensitivity as sound levels got louder or softer.

The GX1 is unusual in being able to provide not only for manual audio level control, but also an on-screen levels display that lets you see if you need to adjust the levels to correctly capture your subject. It's perhaps not the finest-grained control, as the microphone level is controlled in four arbitrary steps, but nonetheless this is more than is offered by some competing cameras. The on-screen levels display offers an eight-step indication, meanwhile.

Unfortunately, it doesn't offer external microphone connectivity, and although the internal microphone has been upgraded to a stereo mic, there is little separation between the mic ports for the left and right channels, leading to a weak stereo effect. Of course, like any camera you can simply use an inexpensive, external digital audio recorder to record a separate soundtrack, and then replace the stock camera audio in post processing, a relatively straightforward process.

Panasonic GX1 Movie Recording User Interface

The Panasonic GX1 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 GX1's top panel, and the camera will start recording video. Video resolution and file format are available via the rear-panel LCD, and you can change these settings at any time via the Quick menu or Motion Picture menu, using either the touch interface or physical buttons. The result is a camera that feels like it was intended to shoot video from the start, rather than one with movie recording grafted on as an afterthought. The quick access to video recording makes it much more likely that you'll use the Panasonic GX1 to record little "video snapshots," rather than it being a big production to switch in and out of video mode.

We've generally favored use of the shutter button to start and end video recording, but found ourselves really liking the convenience of the GX1's dedicated record button. Having it on the rear panel, right behind the shutter button also made it very quick to access with our thumb, so our index finger could remain on the shutter button at all times, ready to capture a spontaneous still image. The touch screen was also nicely integrated into the video recording interface; we found it especially handy for moving the focus point, and used the Quick Menu quite a bit for changing the video recording mode and/or resolution.

One thing to be aware of in recording movies is that the aspect ratio can change immediately after capture starts, if the video and still-capture mode options are set differently. This can be a little disconcerting the first few times it happens. The solution is to either just learn to expect it, or to check ahead of time to see that you're using the same aspect ratio for both still and video capture. There is an option in page four of the Custom menu that determines whether the GX1 should default to showing the aspect ratio set for still or movie capture on its LCD, so if you predominantly shoot one or other media type, you can at least ensure you're surprised as seldom as possible.

A much larger issue is that we discovered there to be a combination of significant lag and anticipation (for lack of a better word) when starting/stopping movie recording. When starting a recording, we found that the recording didn't start until about a second after pressing the Movie Record button. While we haven't tracked this "movie shutter lag" with other cameras, we've seen varying amounts of delay in the video-capable SLR/SLD cameras we've tested in this regard. Somewhat more disconcerting, though was that, as we've seen in some past Panasonic models, the GX1 stopped recording early, with the end of the recorded video coming about a half-second before the point at which we'd pressed the Movie Record button to stop it. This was rather odd in our experience, and led to us chopping off a number of video clips short, ending them before we intended to.

Setting adjustments in movie mode are made via the Motion Picture Menu, which for convenience shares a few items with the main Record Menu. A full list of options can be found below:

Panasonic GX1 Motion Picture Menu 1:

Panasonic GX1 Motion Picture Menu 2:

Panasonic GX1 Motion Picture Menu 3:

Rolling Shutter Artifacts ("Jello Effect")

Essentially every video capable digital SLR/SLD currently on the market 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 Panasonic, 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 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.

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 Panasonic GX1 supports both AVCHD and MPEG-4 recording formats. The AVCHD format is slightly more space-efficient on the memory card, and displays well on HD television sets, but is one of the more compute-intensive formats, and its 1,920 x 1,080 (1080i) resolution means there's a lot of data in each frame to deal with at full resolution. The net result is that you'll want a relatively recent and powerful computer to play full-res high-def video files from the GX1 on your computer. At lower resolutions, and for MPEG-4 video, the requirements will be somewhat more modest. You can, of course, view your movies on an HDTV via the Type-C Mini HDMI output.