23,93 with 50 hz HMI - Is It Possible?

[Ryan Patch]

Hello all –

I’ve seem to run into a unique problem. I am looking to shoot a film in Turkey, a country that runs on 50 hz power, with HMI’s on the RED. I’m told that if we use 23.93 timebase, it will cause a flicker with the HMI’s, as it will be out of sync/phase with the HMIs.

However, doing a 25fps timebase totally messes up post and workflow for a US or NTSC exhibition.

Does anyone have any experience with this? Is there a way to shoot 23.93 with 50 hz HMIs without it flickering? If not, how do you handle post with 25fps media – squishing it down to 23.93 would obviously do crazy things to frame blending. Can we re-interpret the footage at 23.93? What does that do to sync sound?

Please help me out ASAP! Thanks!

Ryan

 

[Nick Gardner]

172 degree/1/50th of a second shutter solves the problem.

Nick

 

[sander kamp]

Yep, we do that all the time here.

 

[Andrew J.]

Hi,

Most of the newer made in Germany electronic HMI ballasts with PFC have a selectable range regardless of the 60hz or 50hz power being fed.

" flicker-free, 60hz, 50hz "

Power the ballasts by 50hz power and select 60hz freq while the camera is at 23.98.

 

[Ryan Patch]

Thanks so much guys!

 

[Aaron Newsome]

I'm in no way affiliated with the guys who make the pCam app for the iPhone, but I've found it to be really awesome for a bunch of cinema related calculations like field of view, depth of field, splits, filters and of course HMI safe shutter speeds. I plugged in 23.98 frame rate and 50Hz HMI. Here's is what I got, hope this doesn't violate the pCam terms or anything.