As we set out for our first shoot with Bob Bradley and the Egyptian National Team for our feature length documentary WE MUST GO, the last thing on our mind was flickering light.  There were permits to get, flights to book, equipment to rent, a list as long as my arm of things to do to get ready for this epic, international shoot.  And after all, we had shot in Africa before, in Sierra Leone, for our doc BROWNSTONES TO RED DIRT (available now on DVD) and flickering light was not an issue in Sierra Leone.  This was, in retrospect, because when we were in Sierra Leone we didn’t have access to electricity so we shot almost entirely with natural light. 

As we reviewed dailies every night in Egypt, we occasionally noticed a little flicker here and there on the LCD screen on our Panasonic AF100 but didn’t think much of it. Even when we looked at the dailies on our larger field monitor, we were looking for other things and missed the flickering light. 

However, when we got home to the US and really started reviewing footage in detail and getting ready to work with it, we noticed a significant flicker in the frame when we were using a light source other than the lights that we brought from home (which were run through Amp and Hz converters).  Stadium lights during the Egyptian National Team’s soccer practice?  Flicker.  The light that was on in the background of our interview with Coach Bradley?  Flicker.

How could I have overlooked that we were shooting in a 50 Hz Country (the US is 60 Hz)?! And more importantly – how do I fix the issue so the next time it doesn’t happen?

Here is what my research has uncovered:

In the US or other 60 Hz countries, we like to shoot at 24p and a Shutter Angle of 180 degrees. We have found that this gets the most film-like look out of our AF100.  We want to mimic this look as best we can.

PLEASE NOTE: We are talking about Shutter Angle and not Shutter Speed.  At the end of this article is a quick guide for how the two relate to each other.

Here’s how we set our camera up for shooting 24p with a 180 degree Shutter Angle in a 60 Hz Country:
Set SYSTEM FREQ from the OTHER FUNCTIONS menu to 59.94 hz
Select 1080 24P from the SCENE FILE menu
Set the Shutter to 180 degrees from the SYNCRO SCAN menu

To eliminate the flickering light when in a 50Hz Country (and to get the same film look) we need to change our Shutter Angle to eliminate the flicker. Go to SYNCRO SCAN and set your Shutter Angle to 172.8d, instead of 180d.  That’s it!  So simple!

Well, the fix is simple, but the math and reasons aren’t quite so.  If you’re a nerd like me and need to know more, here you go:

Here’s the math behind your new Shutter Angle (23.976 x 2) / (25 x 2) = 47.952 / 50 = 0.95904  Then take this number and multiply it by the 60hz shutter angle you normally use: 180 x 0.95904 = 172.63 (this number rounds up to 172.8)

Another way to look at it is, if you are using Shutter Speeds rather than Shutter Angles, if your shutter is not a multiple of the oscillation of the lights (regardless of what the lights are) then you will see flicker/strobing. So… since you are in a 50 Hz environment you would want to us 1/50th or 1/100th, 1/200th etc. 

To find out what electric power frequency your country or a country you are visiting uses, use THIS guide.  

And as promised, here is a quick guide on what

Shutter Angle = what Shutter Speed:

SA  =  SS

270 = 1/32
180 = 1/48
178.8 = 1/50
144 = 1/60
90 = 1/96
72 = 1/120
45 = 1/198
22.5 = 1/348
11 = 1/696
8.6 = 1/1000

The next time we are in Egypt we will not have flickering light!!!  Hurray!!!  Hope this helps you out the next time you are shooting in a 50hz country.