Flickering lights?

Dockland · Jul 24, 2021

I was out the other day filming some test shots (14h work for approx. 7 min "final" result). Boy was that exhausting

It's nothing professional in all means, just me trying out the filmning capabilities with the Canon R5.

I was using my RF 15-35 f/2.8, RF 85 f/1.2 and my EF 600 f/4 III and noticed during some shots the lights were flickering like crazy, don't really know why. I do think it has something to do with the shutterspeed.

I was shooting in manual mode, and don't know how to keep a consistent shutterspeed really. Sometimes I was on f/1.2 with a 3 stop ND-filter and some times on f/4 or smaller with my 600mm (that doesn't have any ND filter) and even my 15-35 with and without the ND filter was used.
It seems like it's under artificial lightning the flickering went mad.

How do I avoid that? Should I shoot in full auto? When I switched to Auto ISO it went straight up to 800 ISO and overexposed everything and I had to adjust the aperture to around f/11 or smaller some times, that eliminated some of the subject isolation I wanted with f/1.2 and even overexposed at f/4 on my 600mm.

All edited in Final Cut Pro (latest version), and I improvised a tune with my midi keyboard in Logic Pro.

Would really love to know the tips and trix to be able to make somewhat consistent footage.

Oh, i filmed in 4K HQ only 4:2:2 Clog 3 and applied Canon LUT afterwards and did some adjustments.

The ratio is strange, I know, but it's made for IGTV and down scaled to 1080*1920 to match the portrait modes on phones/tablets.

Click · Jul 24, 2021

Very nice video. Well done.

Joules · Jul 24, 2021

What framerate are you shooting at? Which country are you in?

Most kinds of modern artificial light aren't giving off light constantly, but rather give off flashes of light periodically. When your framerate is close to the rate at which the lights flicker and your shutter speed is short, your camera can pick up on the flicker. Easiest way to avoid it is to just use longer shutter speeds, which I guess you figured out yourself since you are referring to dark apertures.

For video, you should aim for rather long exposure times anyway, in order to give motion a natural look. The 180 ° shutter is a popular one, and I believe it should do a decent job preventing flickering from showing up.

Dockland · Jul 25, 2021

Joules said:
What framerate are you shooting at? Which country are you in?

Most kinds of modern artificial light aren't giving off light constantly, but rather give off flashes of light periodically. When your framerate is close to the rate at which the lights flicker and your shutter speed is short, your camera can pick up on the flicker. Easiest way to avoid it is to just use longer shutter speeds, which I guess you figured out yourself since you are referring to dark apertures.

For video, you should aim for rather long exposure times anyway, in order to give motion a natural look. The 180 ° shutter is a popular one, and I believe it should do a decent job preventing flickering from showing up.

Thank you for your answer, I really mean it.

I remember I was thinking of keeping my shutter speed around 50 on 23.98 frame rate but on f/1.2 and auto ISO bumping it straight up to ISO 800, well you can tell by yourself how that looked on a bright sunny day

So the shutter speed i was forced to up to around 1000/2000 in some shots, even with the 600mm on f/4.

I don't know if iv'e set it to PAL or NTSC, the one that has 23.98 at least. 4K HQ mode and full manual. Shooting in Sweden.

So is the solution to keep a shutter speed around 50 on ISO 100 (that will be way to under exposed on an evening shot)?
But perhaps an ISO on 800 would have cut it there. As I said, I was alone and keeping every aspect in memory is a challenge (a fun one) but I guess that another couple of ND filters will come in handy. I think practicing is key here, practice, practice and m a k e these mistakes. But always ask here (for an example) if I wonder what/why something didn't turn out as I thought.

Is this the reason some of Canon Cinema line up cameras has built in ND-filter, as the C70, C300 and so on? I mean, is it common to use ND particularly when filming?

I bought it only for stills, so i can shoot a portrait at f/1.2 outdoors on a bright sunny day, and for that it works just great.

Many questions and thoughts, but You guys (and perhaps gals) always have a good advice or two, and a lot of gathered knowledge.

Not trying to be a help-vampire here. Just curios and it's just so much fun.

If there's a YouTube video explaining the rules of thumbs to keep in mind I would really be glad if someone can point to a good one. There are a "couple" out there when I was searching, and didn't really know where to start.

Joules · Jul 25, 2021

Dockland said:
I don't know if iv'e set it to PAL or NTSC, the one that has 23.98 at least. 4K HQ mode and full manual. Shooting in Sweden.

So is the solution to keep a shutter speed around 50 on ISO 100 (that will be way to under exposed on an evening shot)?
But perhaps an ISO on 800 would have cut it there.

They both have 23.98, but the options for PAL are divisible by 25 (25, 50, 100) while for NTSC they are divisible by 30 (30, 60, 120). Since Sweden has a 50 Hz power grid frequency, lights that flicker should flicker at some multiple of that. And so you could get lucky and eliminate flicker in you video by synchronizing your frames with the flicker, which would happen at 50 oder 100 FPS.

However, I don't think there's really a place for the PAL settings anymore, as most digital displays are 60 Hz and neither 25 nor 50 divide into that evenly. Which results in playback artifacts. Variable refresh rate displays are on the rise, but not mainstream yet. Perhaps you view your footage on a TV anyway, which is different. I'm just talking about YouTube content here.

So if you're shooting 24-ish FPS to get 'that look', yes, the shutter speed should be the best thing you can adjust. Ideally, you want to keep that fairly constant across all your shots, as it has a major impact on how the motion in your footage comes across. The 180° shutter speed rule is take 1/(2*FPS) as your shutter speed, so 1/(2*24) = 1/48 ~ 1/50 for your example. That would give motion the 'traditional' look.

There's plenty of YouTube Content on both flicker and 180° shutter out there if you want. I'm not much of a video guy and have no idea which channels are worth anything.

Not really a video aimed at shooting but super interesting and informative anyway:

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