DSLR Movies, Pros and Cons

In my new tradition of rambling on about a subject only to post again a few days later with a more succinct summary of my thoughts, here’s a quick rundown of why you should be excited about shooting video with your DSLR, and why you should reserve some modicum of wait-and-see caution.

First, the reasons to get excited, ranging from the obvious to the more obvious: 

• In the case of the D90, what a sweet deal. $1,000 for the body. I paid nearly that for my HV20. The real win here is that a resolution that is low to medium for a DSLR is positively overkill for HD. Nikon’s “bargain” SLR is overqualified by a mile for 720p video.
• Use your DSLR lenses. If the 5D MkII (or whatever) shoots video too, then both Nikon and Canon peeps can rejoice about this one. A big drawback of the RED One is the expense of the lenses (which need to be top-notch), and a perceived drawback of next year’s Scarlet is the fixed lens.
• A big-ass sensor. The D90’s sensor is roughly the size of the RED One’s. The rumored 5D MarkII’s is way bigger. That means more control of depth-of-field and more predictable results from your stable of lenses. It also means that a $1,000 camera is now making images that, at web resolutions, look an awful lot like those from much more expensive kit.
• 24p. I’m still reeling from this one, but somehow the D90’s video wound up being 24 fps. Hallelujah. It so easily could have been anything else.

And now the reasons to reserve judgement:

• 720p only, at least in the case of the D90. Personally I love 720p, but it’s quite a subset of what your DSLR can do.
• 24p. And that’s all, on the D90 anyway. No overcranking or undercranking. And who knows what frame rates other DSLRs will offer. A camera on which video is an afterthought is not likely to offer a wealth of options here.
• CMOS. CMOS roll. Roll MOS roll. Are DSLR chips, which have never had to fear shearing, skewing and wobbling from rolling shutters (mechanical shutters negate this), going to fare well when recording video? Or will they be jello-cams?
• Limited running time. Aparently there’s some red-tape reason why the D90 is restructed to five minutes of video. Those five minutes will still cost you about 600MB.
• No external audio input. But the D90 does have a mic. You’ll be dual-systeming it. Fortunately there’s cool software out there for syncing audio based on waveform matching.
• Manual control. Although things look good for the D90, the thing about shooting video is that you need the same kind of quick access to key manual exposure controls that SLR stills shooters require. But will the video options be ghettoized in a deep menu?
• Manual focus. Not in and of itself a problem, since that’s how pro video and film gets shot, but that LCD screen won’t be reliable for critical focus at HD res. HD cameras have handy focus-assist features like edge enhancement and LCD zoom.
• You’ll be at the mercy of a codec. The D90 scores well here on paper, but you are still dealing with heavy (and inefficient) compression of a baked-in color palette that may not respond well to agressive grading, as tends to be the case with perceptual compression. This is a tough thing to swallow when you’re holding in your hands a camera that lives and breaths raw formats for stills. Maybe someday someone will make a DSLR that lays down CinemaDNG sequences. Maybe? How about Please God Yes.
• But maybe worse than baked-in color and codecs, you’re at the mercy of whatever the camera can muster in realtime debayering. Most video from compact cameras looks bad not because of compression but because of the hasty techniques used to rapidly build an image from a tiny subset of the sensor’s photosites. I offer up my beloved LX2 as an example—its videos may be 848x480 on disk, but what’s actually present in the images is far less resolution than that. This hard-to-quantify factor could be the real pitfall, although none of the (heavily recompresed) D90 sample vids I’ve seen have exhibited egregious demosaicing artifacts.

I said I’d stop hypothesizing, but this is an interesting enough subject that I felt it was worth clearing the air about both why this thrilling new trend in DSLRs is so great, and why it’s not as great as one might hope.

UPDATE: Mike commented below with a link to dpreview’s sample D-Movies. If you download the original AVI files you can see some sizzle and color sparkle that is symptomatic of the expedient debayering I describe above.

More D90

From robgalbraith.com:

The D90 allows you to select the aperture (from wide open to f/8) prior to commencing, then it handles the adjusting of ISO and shutter speed automatically as needed to maintain video brightness as lighting conditions change during recording. To disable automatic exposure adjustment, it’s possible to lock exposure prior to beginning the recording.

Sounds a bit like the HV20/30 dance to me, where you’re always aiming the thing at a light trying to lock it into 1/48th shutter. Stock up on ND if you want that filmic shutter and shallow DOF at the same time in daylight! Still, if this is true, you can lock down your auto settings and, perhaps somewhat clunkily, explicitly set a shutter speed. 

Of course, unlike Rob, I view the lack of automatic white balance and as a good thing. I’m also baffled by his desire for a digital zoom. I guess what stills folks want from a video camera is different than what film folks want from a stills camera that, uhm, shoots video.

The boards are positively buzzing about this (dvxuser, scarletuser, dvinfo, hv20.com, Rebel Café). There’s some clarification, some idolizing, some bashing, and enough hypothetical confusion that I’m happy to refrain from any further speculation of my own. We’ll see real sample movies and detailed hands-on reviews soon enough.

Still more on this.

SLR Movies

Who is making the movie in this picture?

SLR stands for Single Lens Reflex, “reflex” meaning that the viewfinder shows you the scene through the taking lens by reflecting the light onto a groundglass. The mirror that does this moves out of the way when the shutter is released, contributing to the distinctive SLR shutter sound. In a digital SLR, that same mirror blocks the view to the sensor, making it impossible to preview the shot on the LCD screen.

Lately, this inherent design quality of SLRs has been called into question, as manufacturers realize that temporarily stowing the mirror, eschewing the optical viewfinder and providing a live LCD view has some occasional advantages. It lets them use their fancy contrast-detecting autofocus and face-detection madness, it more accurately previews things like lens boke and white balance. It provides a comfort factor for recent point-and-shoot converts.

And it allows the capture of movies.

That last bit is something that no one has taken advantage of until now. Nikon just announced the D90, which among many impressive features sports not only live view but the ability to capture 720p HD movie files.

The recently cease-and-desisted canonrumors.com has some specs, rumored of course, for the long-awaited Canon 5D MarkII. They include, among other things, a movie mode. Further speculation includes the notion that said movies might be 1080p. I had been wondering what it would take to get me to consider upgrading my 5D, and that would just about do it.

If you study the sensor size cheat sheet, it’s easy to see why folks would be excited by an SLR with movie mode. Most HD cameras have sensors no bigger than an aspirin. But a DX-sized sensor is nearly identical to the Super35 motion picture film gate. You’ll find sensors of this size in the Panavision Genesis, Arri D20, and other unpurchasable digital cinema cameras. The affordable option with a sensor this big is the RED One at $17,500 (body only). So desirable is the shallow depth-of-field look that clever folks such as Redrock Micro have created quite an industry around adapters that allow SLR lenses to be used on various HD cameras. Those adaptors, however, can cost as much as the D90 body.

The sample movies we’ve seen so far from the D90 tell this story perfectly.

The D90’s movie modes are apparently all hard-set to 24 fps. I once had a meeting with some execs and engineers from Nikon, at which I begged them to allow 24fps movie modes on P&S cameras. So I’m just going to go ahead and take a tiny bit of credit for this amazing fact. Not 15 fps, not 30 fps or 60. 24 lovely film-like frames per second. I don’t know what we filmmakers have done to deserve this from both Nikon and Panasonic in such close succession (the LX3 also has a 720p24 HD movie mode), but keep it coming guys. Canon, if your alleged 5D MkII movie mode doesn’t support 24p, then it’s of much less interest to filmmakers.

Many people have pointed out that autofocus won’t work during the D90’s movie capture, thus making it “useless.” Apparently they are unaware that professional film and video shooters almost exclusively use manual focus. If autofocus is occasionally of use on a video camera, it’s because it is designed to work with moving subjects. SLR autofocus is concerned with speed, not smoothness, so it would probably create jarring results in motion as it snapped from solution to solution. The ability to manually focus during movie capture is not something the D90 or a similar offering from Canon could easily disable, since it’s a physical property of the lens. Manual focus during movie capture is a good thing, even if the LCD display on the back of the camera will make critical focus a bit tricky. You could always pipe the HDMI out to an HD display.

Mark my words, you will see rail-mounted D90s with follow-focus rigs and outboard HD displays. And you thought the HV20-based frankenhoopty rigs were ugly.

But there are limitations with the D90’s movie mode that are likely to be endemic. These SLR movies are compressed, heavily. They may or may not be in a format that your NLE of choice supports. The D90 has a limit of five minutes of recording time at 720p.

But probably the biggest potential problem is that there’s no indication of manual control over exposure in these movie modes. I could imagine the aperture remaining locked, but dpreview’s D90 preview explicitly states that exposure in movie mode is automatic. This means troublesome changes in exposure when lighting changes, probably achieved by varying shutter speeds. SLRs have mechanical shutters that are uninvolved with the movie mode, meaning that we will likely have no control over the shutter interval of the movie recordings. We’ll have razor-sharp staccato motion in sunlight and video-like 360 degree shutter indoors, and pulsing exposure settings remeniscent of the worst vacation camcorder strafing. Lame. That’s really the dealbreaker to me. No one will make anything but fun little experimental videos with an auto-exposure-only camera.

(UPDATE: See the first comment below for some hope-inducing contradictions to this concern!)

And that may suit Canon just fine. As Russell Heimlich points out, Nikon doesn’t make video cameras, but Canon does. Canon may well feel compelled to protect their HD video camera line. They may also, like Panasonic, understand filmmakers well enough to outfit their still cameras with movie modes that are interesting and fun, but (carefully) unsuited for any kind of professional work. Or maybe, just maybe, Canon is uniquely poised to unite their SLR expertise and their strong HD camera history into real competition for RED. I get giddy just thinking about a Scarlet-priced, full-frame sensor Canon HD camera that uses my L glass. It sounds crazy but it’s a few short jumps away.

So will you be making a film with your SLR any time soon? Probably not. But you’ll very likely be making movies with it. And if folks like Nikon, with no consumer HD camera line to sabotage, understand the importance of 24 fps, maybe they’ll come to understand the need for manual exposure control as well; in which case the reasons not to shoot your DV Rebel epic with an SLR continue to dwindle.

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