HPX250: Shooting 50 Hz Europe vs. 59.95Hz in America

[benjamin.shearn]

I'm shooting a documentary on dance music in America, Europe, UK and Russia. I would like to shoot 1080/24p, AVC-Intra 100. Trying to get as cinematic a look as possible...

Can someone tell me if I'm getting this right? Because lights in Europe are 50Hz, I should change the timebase on the HPX250 when overseas, as well as adjust my usual shutter speed to 1/50 (unless I need it slower for low light), and possibly even shoot in 25p?

Whereas in America, I should shoot 59.95Hz timebase, 1/60 (usually) and 24p?

My only concern is that the footage matches, gets a nice cinematic good-for-grading look and that I avoid flickering/strobing when shooting clubs in Europe.

Thanks!

 

[Bruce Watson]

Because lights in Europe are 50Hz, I should change the timebase on the HPX250 when overseas, as well as adjust my usual shutter speed to 1/50 (unless I need it slower for low light), and possibly even shoot in 25p?

Whereas in America, I should shoot 59.95Hz timebase, 1/60 (usually) and 24p?

My only concern is that the footage matches, gets a nice cinematic good-for-grading look and that I avoid flickering/strobing when shooting clubs in Europe.

The problem with lights and power grids is that the lights tend to pulse with the rising and falling of the sine wave of the supplied AC power. For tungsten lights, this isn't so bad as the filament doesn't cool off so quickly that you see much variation -- it looks more or less continuous (although it is fluctuating at the power line frequency). It's fluorescent lighting that's a pain. The old magnetic ballasts fire at the power line frequency resulting in very visible flicker.

The way to combat this is to shoot at a frame rate that is an even multiple of the power line frequency. So in North America, 30 frames/sec. In Europe, 25 frames/sec. What this does is make every frame use the same part of the power line sine wave for it's exposure. So every frame is exposed the same way. If you don't do this, what you'll see is a band of darker or lighter exposure on every frame, and it will roll slowly up or down your image at normal viewing rates (at the beat frequency between your frame rate and the power line frequency). Visually very disturbing, and nearly impossible to correct in post.

Unfortunately, doing this means that you can't use one frame rate for all things. And it also means that in converting it all down to a viewing frame rate of 24 fps, you'll be experiencing some pull-down from the 30 fps source. Can't be helped. And 3:2 pull down judder looks a heck of a lot better than a rectangle of lighter exposure that slowly rolls up the screen. A heck of a lot better.

Such is life in the available light world. If you can bring your own lighting, frame rate becomes your choice. If you can't, frame rate becomes the local power grid's choice.