Can’t get to 180 degree shutter, is it worth getting closer?

timmytooltime wrote:

Much of the footage is already shot in 25p, so I’m kind of locked in in that regard, but I’ll definitely keep that in mind for next time.

Err, when I wrote "29.94P", I meant "29.97P". Doh!

I watch quite a lot of 25P stuff - mostly panel discussions or lectures - on a 60P computer display, and motion doesn't look weird.   Maybe if someone was gesticulating a lot it would look odd sometimes.

The part about a "shutter speed equal to the local mains frequency" is important, unless you are sure there are no uncontrolled, flickery, lights near your shoot.

More precisely, you want a shutter speed that:

1. Divides the local mains frequency: i.e.. 1/50, 1/25, ... in most places outside the Americas.
2. If (1) is not possible, divides twice the local mains frequency: e.g. 1/100, 1/33.3, ... in most places outside the Americas.

Say you're shooting in daylight on a city street. It would not be surprising to have parts of building interiors, such as shops and offices, lit by lighting flickering at 2x and/or 1x mains frequency in shot. Which could be quite distracting on playback, even if they're on the edges of the shot.

To a degree, the "180-degree rule" is a myth. Many classic movies were shot on cameras incapable of shooting at 180°, because of the mechanical constraints of very accurately advancing the film between frames. And many classic US movies were shot at 144° (1/60 s at 24fps) to minimise flicker from streetlights, building lights, sporting event lights, and even studio lighting, such as early HMIs.

Some folks who should know better have claimed - and continue to claim - that frame rates that divide mains frequency eliminate mains-related flicker. That would only be true if the mains electrical supply was genlocked to the camera.

But in recent years, lighting flicker has become less of a problem, as LEDs have replaced gas-discharge lamps, and some jurisdictions - notably the EU and California - have introduced legislation to limit lighting flicker in new installations, for health reasons.