Why happen flicker effect on big fps? And how do you fix that?

[Datsenko Alexey]

Hello, guys!
Could you tell me please how often do you meet flicker effect on big fps, 100 fps, 240, fps, 300 fps and how do you fix that?
When I shoot in the interior almost evey time I see flecker on 100,120, 300 fps?
Local lighting is turned off.
Working only with Kino flo, Arri 2000, Arri 1000 and sometime Filmgear (chinese analog kinoflo).
Every lighting brand is flicker free but in practice we see flicker effect every time on big fps.
Theoretically we know that the frequency of lighting id 50Hz and we need to get shutter multiple to 50Hz i.e. 1/50 sec, 1/100, 1/200, 1/500 etc.
But in practice it not works.
We set 120 fps and 1/240 shutter and see flicker, we set 100 fps and 1/200 and see flicker, we set 200 fps and 1/400 and see flicker, we set 300 fpd and 1/600 and see flicker.
Yes when we set 100 fps and 1/100 the flicker is much less but for 100 fps we need 1/200 shutter.
So how do you fix that?
Or may be problem is that Kino flo and Arri not really flicker free indeed?
Thank you in advance

 

[Phil Holland]

See Flicker Free Shutter on my DP Reference Sheet.

 

[Bérenger Brillante]

HMI with their Flicker free setting on ballasts is not really flicker free.
You can see that on more than 75-100fps, depending on the current variation.

Here ballasts have several settings :
flicker free, 1/300 1/1000

Just rent lights with 1/1000 capable ballasts and it will work everytime if you choose the right shutter angle.


Kinoflo (I'm assuming 4banks and alike, not their new leds projectors) are not meant to be used for heavy slow motion. Just like tungsten, on more than 75fps excluded you will have flicker.

 

[Michael Tiemann]

Another way to answer your question is that if you look at the power divisions on a sine wave you can avoid flicker when your shutter speed is 1/2x the frequency or some integer multiple of 1/2 the frequency. (So 1x, 1.5x, 2x, etc.) If you could perfectly sync your genlock with your wall frequency you could also get away with 1/4x the frequency (squeezing 1/200th from a 1/50th of a second system), but as I say, the shutter has to be perfectly aligned with the start of the power cycle to the lamps, and the shutter has to be 360 degrees.

Plot yourself a sine curve, marking the real units of time of the peaks and zero crossings of the power curve, then measure out the frame rate, knowing that the start of the frame time could be anywhere along the power curve. Against the frame rate, show how much time the shutter is open. If the area under the curve is always the same from one opening to the next, you won't get flicker. If the area of the curve changes, you will see flicker. If moving the start time of the shutter gives different answers, you will see flicker.

The bottom line (as others have proposed) is that if you want to shoot 300 fps at 1/600th of a second, you do best with a 1200 Hz electrical ballast (which, coincidentally, is what the Joker Bug HMI ballasts offer). My Joker Bug 800 and a bunch of reflectors makes for a nice high-speed setup in small spaces. A Joker Bug 1600 offers twice the power of the 800.

M

 

[Nawaf Alsabhan]

Hi Datsenko, if you have flicker in a shot, try this Plugin called Flicker Free, it has helped me take out flicker in the past, but it does make the image softer a bit, and works %50 to 75%, works on R3D files in Premiere Pro, but makes exporting much longer so be ready to wait.

https://www.digitalanarchy.com/Flicker/main.html