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How to Gen-lock Canon 5D Mark II cameras & shoot 3D

Every month the

3D Film Factory

receives dozens of calls from Canon 5D owners worldwide asking us how they can gen-lock their DSLR cameras to shoot “in sync� 3D. Unfortunately, we’ve had to tell them that it wasn’t yet possible to gen-lock any of the Canon DSLR cameras, or Nikons for that matter. And yes, you can shoot 3D without gen-locking your cameras, but the 3D will be misaligned and you can’t fix it in post. We’ve tried, trust us. As a matter of fact, we won’t take a 3d production job if the customer isn’t using gen-locked cameras. Why? Because the frames won’t match up, or align and we don’t want to be blamed.

But now, thanks to Peter Clark at Attic Studios, ingenuity has succeeded once again. Mr. Clark has devised a simple, field-tested method for gen-locking the Canon 5D mark II DSLR cameras, and thus creating beautiful, aligned, “in sync� 3D.

Here’s what Mr. Clark suggests to start with, when building a 3D rig using

Canon’s 5D Mark II

– 2x Canon 5D Mark II’s (relatively same age & usage for consistency of shutter age)
– The 3D Film Factory’s 3D-BS MINI or INDIE (beam-splitter) RIG (depends on the needs of the project)
– 2x Canon F1.2 50mm L lenses (set to manual)
– Fresh AAA batteries in battery grip (power supplies may cause power flux)
– Canon made battery grips
– 3x Pocket Wizards Plus II with shutter sync cables (CM-N3-P), one tethered to each camera and one to control shutter release remotely. Again, use fresh batteries.
– 2x Sandisk Extreme IV 8GB CF cards

First, make sure both cameras are restored to the factory settings and in full “manual mode� with freshly installed firmware 2.0.8.

When you’re ready, start both cameras recording video. Then, while both cameras are still recording, take a still frame using the pocket wizard. In this scenario, the cameras should respond simultaneously (you will hear a zipping sound, the shutter).

The theory here is – that the act of taking a still photo while video is rolling “resets” the sensors and begins them scanning at the same pixel line. It seems that as long as the batteries on the Pocket Wizards are fresh, the trigger will remain accurate within a few m/s. Either way, as long as the sensors are scanning in the same direction and not totally out-of-phase, the flickering effect and eye-strain are eliminated – and the resulting 3D is NOT out of sync.

Although this method may seem less than scientific – when tested repeatedly – it worked perfectly on every take.

In order to view the footage in stereoscopic 3D, you simply ingest it into Final Cut Pro (FCP) and setup for side-by-side viewing. Dashwood or Neo3D Cineform might work better, if adjustment was needed, but we had good-looking alignment from the get-go. We proceeded to use a Matrox i/o box to mux the signal to an HDMI out, then to an over-the-counter plasma 3DTV.

We used Black Magic’s mini converters for HDMI to SDI and AJA’s Hi-5 3D for muxing. It should be noted that the live, real-time, 3D monitoring didn’t work because the HDMI signal coming out of the 5D’s was bad. We tried several logical remedies, including re-patches and converters, but no success.

You may also want to try using a photoflash strobe to check the gen-lock . You can see if the sensors are scanning at the same line, as you will get a half white frame when using flash photography (with CMOS rolling sensors).

Information courtesy of Peter Clark at Attic Studios

About the 3D Film Factory

The 3D Film Factory is the leader in professional, affordable 3D camera systems and real-time, 3D viewing solutions. In addition we provide a host of 3D production services for hire, including 3D camera rigs, 3D viewing systems, stereographers, and 3D post, as well as, monthly 3D training workshops. Former clients include ESPN, NASA, Disney, HD Cinema, Pinewood Studios, Attic Studios and Discovery. For more information visit