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How to avoid flickering lighting?

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Sam Baker
How to avoid flickering lighting?
on Aug 9, 2016 at 1:49:03 pm

This piece of footage was shot on a Canon 600D in a room with two soft box lights and the window blacked out: https://www.dropbox.com/s/5qfoapsm28k6mjw/Lighting.mp4?dl=0

There are points where the lighting fluctuates but this wasn't noticeable at the time, and it is consistent in the rest of my footage.

Is there a surefire way to avoid this sort of thing? Is it to do with my camera?


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john sharaf
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 1:56:11 pm

I don't see any flickering
I suspect it's your monitor
Did you shoot at 24P?
Many monitors flicker at this rate
You'll need to monitor at 30FPS (to include the repeated 3:2 pulldown) to view properly.
It's either a setting in the monitor or the editing platform

JMHO

JS



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Gary Huff
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:06:07 pm

[john sharaf] "Many monitors flicker at this rate. You'll need to monitor at 30FPS (to include the repeated 3:2 pulldown) to view properly."

I shoot the vast majority of my content at 24p and I've never needed to set my computer monitor. Pulldown is not required.


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Sam Baker
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:45:18 pm

If you scrub through, it brightens and darkens at points.


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Gary Huff
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:05:27 pm

[Sam Baker] "There are points where the lighting fluctuates but this wasn't noticeable at the time, and it is consistent in the rest of my footage."

I don't notice any lighting fluctuating on my monitor.


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Mark Suszko
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:40:40 pm

Didn't see your sample: I don't make a habit of going to strangers' Drop Boxes. But.

If this was not a DSLR, I would advise adjusting the variable frame speed, what Sony calls: "Clear Scan". I need to sometimes do this when the lighting is LED-based. I don't know that DSLR's have a similar function.

This might be somewhat repairable in post, using color correction tools to select a narrow range and then adjusting just that band to "blow-out" in a steady color/light level. Not perfect, but sometimes saves the shot. There is also some DSLR software that can treat the issue in-camera with a corresponding variance in shutter, but I don


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Todd Terry
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:43:52 pm

I'm directing on location today and not where I can download the footage to view, but I'll throw this out there....

What kind of lamps are in your two instruments?

If they are fluorescent bulbs, that might be the culprit.

Bulbs like halogen and tungsten bulbs are continuous... the hot filament still glows between power cycles and the light is constant. But many other types of light... flos, HMIs, etc.... are not continuous... they actually quickly flicker along with the 60Hz cycle of the power. If this is not in synch with your camera shutter, you will get troubles. It can be anywhere from a rapid flickering to a slow phasing over a several second period.

I'm not saying that's your issue, but if it is then you need to shoot with a shutter speed that is exactly the same as the AC power source. This requires a camera with a shutter mode usually known as "clear scan," when you dial in the exact correct shutter speed... so instead of setting it at 1/48th or 1/60th, it's more like 59.043 or 60.849 or whatever.

I don't use DSLRs to shoot video, but I'm doubting that's something your Canon will do. You'll need a proper (and higher end) video camera to do that. Or the easier/cheaper fix... use continuous lighting... e.g. tungsten, halogen, or LED (note that most but not all LEDs are flicker free these days. Any that operate on batteries will be, but AC powered ones might flicker, especially ones that do not use a transformer to step the juice down to 12V DC).

On another note... I too shoot 24p almost exclusively. I've never had a monitor flicker, whether it be a high-end "real" monitor, LCD, LED, CRT, or just the cheap 12V LCD TV that we sometimes use.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Todd Terry
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:50:12 pm

"If you scrub through, it brightens and darkens at points."

Is it uniform and regular?... as in, does the brightness hit its peak at uniform intervals, such as every five or eight seconds or so, exactly the same over and over? If you speed up a clip where this occurs it is often more evident... something that looks fine at normal speed will show brightness differences when played back at, oh, 800%, or when scrubbed through.

If that change is precisely uniform, that's the phasing I was talking about in the post above. In that case you need to change the light source to a continuous source, or shoot with a camera that has a clearscan mode.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Sam Baker
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:00:00 pm

In that clip, there is a bit of an ebb and flow, with it getting brighter and then darker about three times (but static for the first 5 seconds).

However, in most of my other footage with the same person, it's not there at all and the lighting stays consistent, with a few dips towards the end.

It was all shot in the space of 20 minutes so I don't think it's phasing.


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Sam Baker
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 2:54:02 pm

These are the lights: https://www.amazon.co.uk/gp/product/B0089HTJE4/ref=oh_aui_detailpage_o03_s0...

I think they're LED and it says continuous in the listing. The footage was shot at 25p and I need it that way.


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Todd Terry
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:02:40 pm

They're throwing around the word "continuous" in a different way than we've been talking about it here. They just mean they are not strobes that flash. That doesn't mean they are true continuous lights.

That Amazon listing is very light on exact specs.... but based on the fact that the instruments are dirt cheap and that they are listed at 80 watts and plug directly into AC power, then I guarantee you that they are flos, and that very likely is your problem.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Todd Terry
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:07:26 pm

Duh on me... I looked at the ad again, I didn't even notice before the small pictures beside the real one.

Note the one where you can see inside the softbox. Those are very definitely and without question flos. Looks like just a standard spiral compact fluorescent bulb (although of higher wattage than you usually would buy for, say, home use).

Combining that with your DSLR is the troublesome combo, I'd bet the farm on it.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Sam Baker
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:09:03 pm

Great thanks, I'll have a look for some better ones.


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Todd Terry
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:17:02 pm

Those are just plain ol' Edison screw-in sockets... so in a pinch you could just put tungsten blubs in them, which would be continuous.

I'd just be careful about it though, while the flo blubs get a little warm, the tungsten bulbs get hot, and the softbox might not be made to withstand hot lamps... so I'd go with as minimal a wattage as you can get away with, keep a close eye on it, and never leave them on unattended even for a second. Not the best solution of course (and you definitely don't want a fire), but it'd work. You could put tungsten bulbs in them and test it for a little while outdoors where there's no danger.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Sam Baker
Re: How to avoid flickering lighting?
on Aug 10, 2016 at 5:16:50 pm

So do you think any old tungsten bulbs would work... like these? http://www.ebay.co.uk/itm/E27-40W-Vintage-Retro-Filament-Edison-Tungsten-Li...


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Todd Terry
Re: How to avoid flickering lighting?
on Aug 10, 2016 at 5:25:56 pm

Why would you want to use specialty vintage-style bulbs?? If you want to try tungsten bulbs, just use regular ol' bulbs from the hardware store. They'll give much more uniform light, probably a slightly lower color temperature, and will be a great great deal cheaper.

When I said "Edison" before that was just referring to the size and type of socket... I didnt mean actual vintage style Edison bulbs.

You could also try the screw-in household LED bulbs that have an Edison base, which would be much cooler...but i cant guarantee they wont flicker.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Sam Baker
Re: How to avoid flickering lighting?
on Aug 10, 2016 at 5:27:32 pm

I just didn't expect something so cheap to work well for it. I'll report back in a few days...


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Sam Baker
Re: How to avoid flickering lighting?
on Aug 12, 2016 at 4:43:03 pm

I've bought two of these halogen bulbs: http://gerardlighting.com.au/products/lamps/classic-eco-a55

I tested it in the daytime with the curtains closed and someone talking to camera... without lights, fluorescent and halogen.

There was a similar amount of "flashing" between the fluorescent and the halogen footage. And no variation when I wasn't using any lights.

I then tried it at night, so perfect conditions, but with nobody in the frame.

The fluorescent appears to gradually get darker: https://www.dropbox.com/s/34rqwb313m7sygn/Halogen%20lighting.mp4?dl=0

The halogen is consistent throughought: https://www.dropbox.com/s/34rqwb313m7sygn/Halogen%20lighting.mp4?dl=0

So now I'm thinking it's something to do with my camera, that it's adjusting the exposure when someone's talking/moving.

I set the exposure to manual though.


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john sharaf
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:28:57 pm

OK Sherlock, lots of clues here!
Seems like you're in the UK, shooting 25FPS, and you bought these lights thinking in GBP thinking they'd work in the UK, but looks like you might have gotten "US" model. Any markings on the box?
Perhaps the Flo-Globes are 60htz not 50htz, just buy replacement globes locally and you're on the air.

JS



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Sam Baker
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 3:56:07 pm

Yes I'm in the UK, yes I'm shooting at 25fps, and yes I thought they'd work in the UK.

The box has some instructions inside that say "Rated: 160-260V, 50/60HZ, E27*1*MAX.80W".

And on the outside of the box the same thing: https://s9.postimg.org/478d0u9zj/lights.png


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john sharaf
Re: How to avoid flickering lighting?
on Aug 9, 2016 at 4:03:28 pm

Of course. That's what it should say.
All I think is that at such a low cost for the complete light, the fluorescent globes are at such a low quality that they flicker enough to be seen with the shorter motion picture exposure, but is not so apparent to the eye/brain.
I'm afraid you're getting what you paid for!

Cheers,

JS



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