flicker free speeds

[utku sonmezer]

couple of days ago we were shooting a commercial at night ext with epic. Director asked for slow motion. Since a lot of street lights were also illuminating the frame. We were only able to shoot at flicker free speeds. In our case it was 33.333, 50 or 100fps since i live in Turkey which is a 50hz country. I dialed in 33.333 in fps menu but it kept flickering. There was no flicker at 50 or 100 fps. What do you guys think ?

edit:shutter angle was always 180 degrees

 

[Koray Birand]

You actually have answered your question. 50hz.. So you are safe up to 75 fps . I doubt that you got a flicker free at 100fps, did you check the footage on a large monitor ??

Always check your histogram, if the channels are bouncing even very little . It means you have flicker. You can not see it from the viewfinder nor lcd.
And the worst part is sometimes you think that you do not have flicker but after post it appears. So if you are going to shoot slow motion always do a pre light...

 

[utku sonmezer]

i actually havent answered my question. Because 50hz safe speeds at any shutter angle are 25, 33.333, 50, and 100. 75 is not a flicker free speed and you get flicker. Yes i did check the footage on a large monitor. What confuses me is that. Even though 33.333 is a known flicker free speed why did i get flicker?

 

[Robert Andriessen]

there is an app for that 'flickerfree'
havent had the chance to try it yet though