Post Production Technology News

SA first to test new RED HDRx process

Tue, 20 Sep 2011 14:56

A revolutionary new way to expose video was given its first South African test on the SABC’s 2011 IRB Rugby World Cup campaign. Lucky Bean Media director Chris Green was tasked with helming a spot for production agency Eject Media which involved scenarios where ordinary South Africans show their support for the national rugby team, the Springboks, in interesting and creative ways.

“Our story revolved around a young girl on a bicycle transporting a rugby trophy through the South African landscape, passing through scenarios that show a growing tide of support for the Boks,” said Green. “We wanted a sense of realism and fluidity and so chose to film as many of these scenarios as possible in a single take.”

Director of Photography (DOP) Adam Bentel had to light a scene that required an inside-outside exposure. “The shot needed a camera to move inside a mechanic’s workshop but it had to start on the young girl riding past the workshop door in broad daylight,” explains Bentel. “As this was a single, fluid camera movement, it required two separate exposures – one for the interior and one for the exterior.”

With time and budget constraints, Bentel chose to explore the HDRx function on the brand new RED Epic camera system, which involves two separate video streams. “HDRx involves setting the camera to record two separate streams of the same footage at two different exposures,” says DOP David Pienaar, the camera supplier on the project. “This allows you to blend the two exposures to get a greater exposure range – RED claims up to 18 stops – resulting in a much greater dynamic range.”

Satisfied with early tests, on the day the team pulled off the shot without having to light the interior, save for practical lights and natural light.

“We used an 8x4 silver bounce inside to create a bit of contrast on the performers and this coupled with the practical LED strips on the underside of a raised car, provided all we needed for interior light,” says Bentel. “We shot with a set of ARRI CP2 and being fairly fast lenses (T2.1), I closed to my incident reading of f5.6 (my preferred f-stop) and programmed the RED Epic’s HDRx function to record a simultaneous motion image at six stops under f5.6.”

The team was able to check results immediately by downloading the card and creating a preview blend of the two streams through the RED Cine X software’s Magic Motion, something Bentel was more than happy with. “The results were immediately visible through the blend, and we could safely ascertain that we had exposed correctly for the shot to work.”

Post process

With its offline cut locked, Eject Media took the footage to Pudding Telecine Services where Colorist Nicholas Apostoli provided the blend of the two exposures through the Baselight system. “Using the Baselight’s ability to read the main exposure channel (A Track) and the HDRX (X Track) channel simultaneously, we were able to recover normally lost highlights and combine both in one pass,” says Apostoli of the process. “Before this, unless you had a motion control rig, it was not possible to get perfect exposure inside and out on video, utilising this lighting set up.” The process required a simple rotoscope, which was achieved quickly and efficiently.

“Traditionally this kind of effect would then have to be done in two passes, rotoscoped and then composited in a tool like Flame. But with the RED Epic’s HDRx capability we achieved the shot without having to leave the Baselight suite.”

“This process allowed us to shoot quickly and create the sense of fluidity that the shot required, without having to spend inordinate amounts of time on lighting set-ups,” says Green.

Limitations

Like any new technology HDRx does have limitations, such as shooting scenes with a lot of motion. “The X track’s lower exposure is acquired by changing the shutter angle of each exposed frame, thus exposing each frame with less motion blur, creating a crisper track,” explains Pienaar.”

However, new technology leads to new methodologies, something Pienaar and Bentel are very excited about.

“Having a crisper X track could come in handy on shots requiring effects such as keying, allowing the X Track to act as a built-in mask for the compositor, and allowing the A Track to handle a high degree of motion blur at wider shutter angles,” notes Pienaar. “The X Track can also be used to fire off stills during shooting, at an acceptable crispness for print.”

Both stress that HDRx should also not be used as a replacement for lighting, mentioning that the RED HDRx process is an extra string in the bow of a cinematographer. “HDRx shooting is something I would recommend as a creative tool when shooting for a realistic look, and when under time constraints,” comments Bentel.

“I’ve always been a fan of special effects that don’t draw attention to themselves,” adds Green. “Here we have a shot that aided the sense of realism and pacing that the edit required, yet set-up and logistical problems were virtually eliminated by a very neat technological innovation. “It’s a tool that could greatly aid filmmakers to tell their stories.”

SCREENAFRICA Print Magazine – October 2011 (view here)

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