High Speed Video

AbelCine in New York City was kind enough to lend us Jesse Rosen for an interview about high speed cinematography. Jesse answers some common questions about shooting at high frame rates, and gives us some other important tips. Enjoy the video above.

I’ve had a lot of requests for more information about the samurai swordfighting footage seen in the video. That is from a short film that is in post production. I’ll post the short here as soon as it’s done – I promise! The actors are part of Samurai Sword Soul.

 

Side notes I trimmed from the interview for brevity

Additional flicker-free light source

Jesse mentioned an additional light source for high speed filming: xenon arc lamps. When powered by a DC source, they will be flicker-free. They are very high intensity. Think searchlights.

Reducing motion blur: Strobes

Another way to reduce motion blur is to use strobes, which must be synchronized with the camera. They fire once per frame for 1/100,000 of a second. Even though the video is capturing, say, 500 frames per second, with a strobe, the light is only on for a tiny fraction of that time, so each of those 500 frames is razor sharp.

Classically, strobes are used for food commercials with soda cans opening and fruit spritzing, where you can see every drop of liquid. You need a dedicated strobe system designed for video or film, like ones made by Unilux. They max out at about 500fps.

Practicals

After carefully selecting the perfect production lights for your high speed shoot, you might have forgotten something…. practicals! Lights that are part of the set, cell phones, TV screens, monitors, little LED lights on devices and office phones will all tend to flicker when filmed at high speed. Those objects are often taken care of by a different department, so there needs to be coordination to replace those (or remove them) in order to eliminate distracting flicker in the shot.

 

Some Advice from my experience

I want to buy one

As much as we’d all like to own one of these cameras, a more likely scenario is that if we need it for a special situation, we’ll rent one for the days we require it.

Manufacturers don’t like to publish prices for products in this price range, but just to give you an idea, a Phantom Flex is going to run you somewhere around $100,000, plus cinema lenses, of course. The CineMag flash memory storage modules are in the tens of thousands of dollars each. They allow you to store about an hour (at playback speed) of footage (which is a lot for high speed shooting) before you have to download to a hard drive.

So, buying a camera like this only makes sense if you want to make a living doing high speed video for clients, or else you plan to rent the equipment to production companies to make back your investment.

Okay, then I want to rent one

Rental for the day including camera, lenses, and a CineMag is about $3000. Note that most rental houses will only give this to a production team with a certified high-speed camera operator. He’s going to be another $800 for the day.

Alternatively, someone on your team can take the certification class. They’re pricey, but you can do it in a weekend.

Other brands and workflow

Weisscam is a newer company also making high speed cinema cameras with very similar specs and prices.

A note on workflow. Like the RED and ARRI Alexa, the Phantom and Weisscams record to a 12-bit RAW data format. That gives you enormous flexibility in post for color correction and format resolution. But you have to add that to your workflow plans. You’ll be dealing with proprietary software, mountains of hard drive space, and days of file transfers.

As an option, the files can be easily transcoded to an HD format when you’re saving them to a hard drive. But then the initial color grade is baked in, and you’re stuck with HD resolution. Depending on your project’s delivery, this may be fine.

Never mind, I’ll fake it

When you need 2,000 frames per second, there’s no getting around a real, dedicated high speed system. But consider, for people moving around and doing martial arts or sports, you might be able to shoot at 60fps or 120fps and do a significant amount of slowing down or speed ramping in post.

If you’re playing back at 24fps, you’ve already captured enough frames to reduce things down 2.5 (60/24) or 5 (120/24) times slower than normal speed.

Software like Twixtor, and Timewarp in After Effects are good cheats. This isn’t a tutorial on how to use those, but generally you want to

1. Shoot with a very fast shutter speed to get crisp frames and no motion blur.
2. Shoot at your maximum frame rate. Many video cameras will shoot 60p.
3. Shoot against a plain background that is visually different from the subject.
4. Lock down the camera.

These parameters make it easier for the software to pick out the details of the subject; and determine what’s supposed to be moving, and what’s static in the frame.

When you’re planning your shoot, remember that you’ll need more light than normal, because your shutter speed is so fast. If you’re shooting at 1/2000 sec, that’s 5 or 6 stops darker than 1/50 sec you might be used to shooting.