High frame rates and flicker

D

dmitrizigany

Veteran
Hey,

I have a shoot in about a week that will be shot mostly in slow motion.
It will be shot at a sportsing arena. We will shoot both in the dressing rooms and on the actual field/runway/whatever it's called where they run around.

With some luck the lights will be good enough out on the arena... But most likely not in the dressing room.

Very limited budget and not sure we can bring any extra lights at all.

are there any tricks (at time of shooting)? Will 100fps work instead of 200fps, for example? I'm shooting in Europe (Sweden), would switching to 120/240 improve things?

And yes, you guessed it, there's no possibility of going there to try things out or knowing what light is available there.

I know there's ways to at least partially fix things in post, but want to have best results in camera.

Will I see the flicker on the Odyssey 7Q+ monitor? (With FS700 built in it was almost invisible until footage was imported)

thanks
 
You will see the flicker only when you play back, as your realtime shooting speed will negate the slow motion artifacting. But you can quickly shoot a test on the day and play back on the Odyssey7Q+ to check for flicker. Turn on the waveform in the lower right corner. Your eyes may fool you about seeing flicker but the waveform bouncing up & down will not lie.

Since you are shooting in Europe all the power should be at 100hz frequency. Don't go 120/240 as it is not cleanly divisible into 100, so different frames will have different exposure (flicker!). There should be no flicker at 100p, and you may even be okay at 200p. That is dependent on the nature of the lighting at the venue which is why you won't know until you try. Remember, from 25->50->100->200 fps, each doubling is a stop of light. You very well may not want to shoot at 200p simply because you don't have the light for it. That's three stops down from 25p.
 
I saw a video about a guy who was able to get rid of flicker by duping the video, putting it on another layer (track) in FCPX, and shifting it one frame over. Then he fiddled with the transparency of the upper video track to get it right. The difference in the position of the subject from frame to frame was virtually un-noticeable, and the flicker was darned near completely eliminated. I haven't tried this trick yet, but what I saw of his footage was very impressive.

If you do end up with flicker you might want to try this hack to deal with it. Good luck.
 
Disambiguous66 said:
I saw a video about a guy who was able to get rid of flicker by duping the video, putting it on another layer (track) in FCPX, and shifting it one frame over. Then he fiddled with the transparency of the upper video track to get it right. The difference in the position of the subject from frame to frame was virtually un-noticeable, and the flicker was darned near completely eliminated. I haven't tried this trick yet, but what I saw of his footage was very impressive.

If you do end up with flicker you might want to try this hack to deal with it. Good luck.
Click to expand...

If you could link the aforementioned video that would be hugely helpful as I've airways assumed that was the cost of doing business with certain lights over others.
 
70Deep said:
If you could link the aforementioned video that would be hugely helpful as I've airways assumed that was the cost of doing business with certain lights over others.
Click to expand...
It's really easy, you just duplicate the footage and drag it over the original. Then move it one frame and reduce the opacity to 50%... You loose a bit quality. But flicker can go away. It's no substitute for getting it right in camera, but can save your butt sometimes...
 
Would this loss of quality be on overall sharpness or would it be something like the equivalent of footage shot in true 2k now appearing in 1080p.

Also, any idea if that would cause any weird banding, artifacts or moire etc? I see you have an fs700 so i assume you've done this trick in a pinch once or twice.
 
It adds a bit of blur and so. Will most likely be more pronounced in shots with fast movement as you have one frame appearing two frames in a row although at 50% opacity.

I haven't tried it so much. The one time I tried it on a production it worked fine enough for the shot to be usable. I can count the times I've shot slow motion on one hand during my 2 years with the FS700. Mostly because of the flicker. I almost never shoot in daylight and don't have lights that don't flicker so I avoid it mostly because of that.
 
dmitrizigany said:
I can count the times I've shot slow motion on one hand during my 2 years with the FS700. Mostly because of the flicker. I almost never shoot in daylight and don't have lights that don't flicker so I avoid it mostly because of that.
Click to expand...

Wow striking news. I thought that's why most people chose the fs700 over other cameras. Is the flicker any better with the odyssey or is it same or worse because the video quality is better?


Also a question based on the OP's question. In his scenario if he filmed tighter shots of the athletes rather than wider ones would the flicker be less or more notable?
 
70Deep said:
Wow striking news. I thought that's why most people chose the fs700 over other cameras. Is the flicker any better with the odyssey or is it same or worse because the video quality is better?
Also a question based on the OP's question. In his scenario if he filmed tighter shots of the athletes rather than wider ones would the flicker be less or more notable?
Click to expand...
Yes, I thought I would use slow motion more. But also didn't know so much about the problems of flicker before I bought it. But the main reason I got it wasn't because of the slow motion but for the versatility of the camera. And the relative future proofing with 4K compared to other cameras available at the time.
I think closer or wider shots don't matter much.
In the end it turned out to bemainly daylight through windows... Can't remember, maybe we got flicker at 200fps but it was fine at 100. Think I ended up shooting mostly in 50p after all. Mostly because the pain in the bottom of switching modes on the Odyssey 7Q...
 
The flicker is purely a function of the camera frame rate and its shutter interacting with the non-continuous light. Recording internally or externally makes no difference. Framing makes little difference as the same non-continuous light is still hitting the subject being photographed.

All is not lost. At 100p in 50z countries and 120p in 60z countries there is rarely flicker. Most light sources will remain continuous enough not the show any flicker. At 200p/240p is where you'll usually see the flicker.

A DC tungsten light is continuous and will not flicker, but a tungsten light plugged into AC power will. A powerful AC powered tungsten light like a 2K won't flicker simply because the bulb is so freaking hot that it doesn't have time to cool before the next cycle comes. Most professional LED fixtures will not flicker if set to full power, but if you dim them many will flicker wildly as they use Pulse Width Modulation (PWM) to control brightness (literally, they flicker instead of remain on in order to be dimmer). Most professional HMI and Fluorescent fixtures with proper electronic ballasts will likely not flicker at these frame rates (magnetic ballasts generally went away decades ago unless your using a really cheap shop light). When you get into the more expensive lights then you pretty much price yourself out of the flicker.
 
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