Issues shooting at 50hz in the US?

[Todd Sheridan]

I know this is not a question specific to the FS700, but that is the camera I will be using, so I guess this is a good place to start.

I am shooting tomorrow in the US for a client based in Asia, and they would like the footage shot at 25p to match previous footage they shot for the same project.

If I switch to 50hz so I can record at 25fps, what are the chances I will run into issues with the lights flickering, etc?

I will be lighting for an interview (using a kino flo diva as key and Arri Fresnels as fill, etc) as well as b-roll using whatever practical light is available at location (don't know what that will be).

And if I do see flicker, will I presumably be able to adjust my shutter speed to correct the issue?

Unfortunately, I will not have a decent sized monitor, so hopefully if there is flicker, it will be obvious on the small LCD.

I also wonder if, for whatever reason, there is a flicker issue, whether I am better off staying at 25p and living with it, or switching to 24p and hoping they can match the different frame rates in post.

Thanks

[Christopher Young]

Whether shooting 50i or 25p in the States, or any 60Hz country, set your shutter to 60th of a second if you whish to eliminate that annoying 10Hz flicker between the 50Hz shooting rate of a PAL configured camera when shooting in a 60Hz lighting environment.

On the FS700 you will find you cannot adjust the shutter speed if you are on auto-focus and face recognition is turned on. That's assuming that the kit lens is on the camera. If using that lens just switch to manual focus and then you can adjust the shutter.

50Hz shooters are lucky as we only have to go up to a 60th to eliminate that 10Hz flicker whereas 60Hz shooters shooting in 50Hz countries have to go to 100th a second. That's the closest multiple of a 50th, that they would have to use to minimise the 10Hz lighting flicker they would get shooting at 60i or 30p.

Chris Young
CYV Productions
Sydney

[Todd Sheridan]

Thanks Chris. I should have tested before I posted. As I changed shutter speed, it was very obvious even in the LCD that changing the shutter speed dealt with the flicker issue.

I will say though, even at 1/60th, although I can no longer visually see the "flicker" in the LCD, on the histogram I am still seeing a fluctuation in exposure.