While these cameras can produce stunning imagery, they also have several disadvantages when shooting video.
The HDSLR: The Future of Documentary and Video Journalism? - by Ted Roach and Larry Engel (page 2)
After absorbing all of Larry’s initial thoughts, I’m basically ready to go buy a 5D and get to work! However, it’s always a good idea to also ask about the disadvantages, and Larry is happy to lay those out as well. The area that seems most problematic to him is audio. When trying to record sound on the camera, there are several limitations to the HDSLRs. The first issue is that these cameras do not have headphone/monitor outputs. As anyone who has worked with audio knows, it is very important to monitor the sound coming into the camera or recording device for both levels, and for electronic interference on radio mics. Without headphones it is impossible to monitor the audio for problems such as these, and very easy to make mistakes. The audio level controls are also usually limited. In fact, some don’t allow the shooter to set the levels at all (however the Canon 5D and the Panasonic GH2 offer some manual controls and visual level monitoring). When they do allow adjustments, most do not enable the user to make changes during a shot. In practice, this has meant Larry has had to stop shooting to readjust his levels, and then start recording again. The one built-in solution that all of these cameras offer is automatic gain control (AGC). While it’s next to impossible to capture high quality, professional sound when using AGC, Larry thinks some less experienced users would prefer this option over manual control anyway.
For the professional however, the bottom line is that if you want clean, crisp audio, you better look into recording sound off-camera with a double-system package. The Zoom H4N has become one of the industry “standards” for double-system sound recording. This MPG3 recorder (to a standard SD card) allows for two separate XLR inputs, audio monitoring and level controls. When shooting double-system, you also have to make sure that either you use the old film technique of a clapper, or you need to have a good control track of the audio recorded on the camera itself (Larry uses a small Sennheiser mic attached to the hot shoe of the camera for this, and for many other audio recording needs). A double-system also means a second crewmember may be needed, and you will have to deal with syncing the audio to picture in post-production (Final Cut has a plug-in for auto-syncing and there is also a separate stand-alone syncing program for AVID at this time). For shooters experienced in shooting film such as Larry, this is not a deal breaker. In fact, he actually prefers being un-tethered from the audio in almost all situations. For the one-person crew or backpack journalist however, you should give serious thought to these issues before investing in an HDSLR.
On the video side there are a few drawbacks as well. HDSLRs are notoriously problematic in recording motion or fast movement. Since these cameras record with H.264 compression (as many of the newer model HD camcorders also do), the resulting footage is compressed through long GOP (Group Of Pictures) codecs as opposed to I-frame codecs. While this is an extremely efficient method for capturing and encoding high-resolution images, it does create issues, including some regarding motion. Click below to hear Larry’s explanation:
Basically, long GOP reduces the data rate of recorded footage by encoding and packaging the information from sampling and recording every 5th frame or so, instead of the traditional I-frame method, which records each frame separately and independently of the others. As Larry explains it, the camera essentially only records 5 full frames per second, then on playback or ingestion into an editing program “fills in” the rest between these full frames. When the camera is steady or the subject’s motion is limited, this is not much of a problem. But when the camera is moving quickly or the subject’s movement is great (especially laterally within the frame), the resulting images can look jittery and contain video artifacts. Further, with very fast on-camera movement there can be some bowing of vertical lines, or what’s sometimes called “Jello-ing.” That’s because the shutter on these cameras is not a “snap” shutter but a “rolling” one. Rather than the conventional shut-open-shut actions of a standard shutter, the rolling shutter essentially scans down the chip for the allotted shutter speed. So a fast-moving object that starts at the right side of the frame may be center-framed by the time the shutter ends its scan. Larry cites this as a big concern of his when he shoots, and a problem inherent in the cameras’ design.
Another HDSLR video issue is image stabilization when shooting handheld. For shooters accustomed to larger, shoulder mounted ENG cameras, the smaller, lightweight HDSLRs are much harder to hold steady. They’re even harder to hold steady than camcorders, partly because the cameras themselves don’t have image stabilization. Some of the HDSLR’s offer optical image stabilizers (OIS) in camera, but this feature can sometimes interfere with recording clean video. Larry recommends that videographers who rely heavily on handheld work take this factor into serious consideration before choosing a camera.
One often-cited disadvantage of HDSLRs is overheating. Since DSLRs were originally designed to take stills alone, the added capability of constantly shooting video at 24 or 30 frames per second for extended periods puts a heavy workload on these small, compact cameras. This can lead to overheating, which has proved problematic for some models of HDSLR, most notably the Canons. Click below for Larry’s thoughts on overheating:
Partly this is due to the energy needed to keep the mirror in lock up position. Since the Panasonic doesn’t have a mirror (it has a EVF constant “live-view” instead), it is less prone to overheating. Larry has experienced this issue, and describes the problem when the warning light comes on as either degrading the quality of the image or, in a worst case scenario, the camera automatically shuts itself down. As an example, he recounts shooting in the Arizona desert under 106-degree heat. The camera was hot to the touch right out of the case, even before the shooting started. As this was one of his earliest experiences with HDSLRs (Canon 7D specifically), he wondered how well it would hold up. While the light did appear several times, he approached the issue as if he were shooting with motion picture film. In the past, he needed to allow for time to change film magazines and camera batteries, and the HDSLR has its own set of time limitations too. When I asked why this issue comes up so often when talking to other camera operators about HDSLRs, he theorized that in today’s fast-paced video world, shooters, directors and producers have become accustomed to thinking they have to shoot constantly. This is an inefficient and sloppy approach. If you plan a shot list/schedule in advance, and manage your shooting environment, this does not have to be a problem. Admittedly, during “run and gun,” observational shooting, or for some interview situations, this can still be a concern regardless of planning. Despite these constraints though, Larry tells me he can honestly say that he’s never lost a single shot due to overheating, even when working in some of the hottest conditions on the planet.