Flicker on a 7D in a 50hz country(Shutter speeds)

[Ross Webb]

Hi there
I am in a country where the refresh rate is 50hz.
I am looking at various options on shutter speeds for 720p 60. The shutter speeds of 125 and down don't show flicker but over 125 do. Has this been everyone else's experience as well on the 7D? Of course at 25fps its great and at 24 we're having the same problem above 125 shutter speed.
Looking forward to hearing people's experiences and advice on this
Ross

[William Japhet]

When you shoot with shutter over 100 Hz, you will see this problem with all cameras, HD or not.

In fact, you see the "light's refresh rate", specially with old fluorescent lights (fluorescent lights or with sodium lights in industrial environment for ex.) so you see the light in its "OFF phase" and sometimes in its "ON phase".

Over 100 Hz, the "camera capturing time" is too short to see the light always ON, like our eyes.

If you use cine specialized HMI lights, or incandescent lights, you can work with higher shutters.

Regards,
William.

[Floris de Rijke]

I recently had this problem while shooting 24p. Was shooting a scene that was partially lit by a flat screen TV and first shot about a dozen clips on 24p with shutter speed set to 50, then a few clip on 50p and back to 24p there suddenly was a horrendous flicker. Solved it by shooting on 25p from there, but of course far from ideal.

The weirdest thing in my mind was the fact that it only showed up after shooting 50p, definitly not before since back home I checked all footage on a big screen and the first dozen clips showed no flicker artifacts whatsoever.