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Zoom Q2n video flicker fix?

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Zoom Q2n video flicker fix?

PostPosted: Tue Oct 13, 2020 12:49 pm
by maxed
I have a Zoom Q2n 'handy' video/webcam I use for video recording, Zoom music meetings, etc. The room I mostly use has LED lighting, and on default 720-30 video settings the Q2n shows pronounced lighting flicker at night. I suspect that's because it's designed for 60 cycle US etc mains lighting rather than 50 cycle UK mains. The camera also has 1080-24 and 720-24 video settings. Should say 720-24 get rid of most of the flicker even though it's not an exact divider of 50 cycles, and would using incandescent rather than LED lighting help? Also, has anyone found any of the Q2n's selection of different lighting scenes helps with this?

Thanks, Max

Re: Zoom Q2n video flicker fix?

PostPosted: Tue Oct 13, 2020 7:15 pm
by Tim Gillett
You might be better asking on a specific video or cinematography forum.

Re: Zoom Q2n video flicker fix?

PostPosted: Tue Oct 13, 2020 8:37 pm
by maxed
I might, Tim, but the guys here are much more likely to have and use something as low budget as a Q2n camera than AV folks. Last time I asked an AV forum something the answer started at £4k :)

Re: Zoom Q2n video flicker fix?

PostPosted: Tue Oct 13, 2020 9:02 pm
by blinddrew
That happens here too sometimes... ;)
I guess the thing to do is try it and see, but i'd be tempted by the incandescent route.

Re: Zoom Q2n video flicker fix?

PostPosted: Wed Oct 14, 2020 9:58 am
by The Red Bladder
I do not know the Zoom Q2n but the answer is always and only 'shutter-speed'.

Set the shutter speed to a slower setting and the flicker goes away.

Tungsten lights do not flicker because of 'Thermal Inertia' - i.e. it takes many milliseconds for the filament to heat up and cool down and the larger the filament, the longer it takes - up to a second for a 2kW halogen. Fluorescent tubes pulse on and off at mains frequency. If your mains is 60Hz then you get 60 positive pulses and 60 negative pulses - so the tube flickers at 120Hz (100Hz in Europe).

LEDs pulse on and off at high speed and that speed varies but is usually around 2-4kHz, i.e. 2000 to 4000 times per second.

Digital cameras can suffer flickering and pulsing when the shutter speed is either a factor of the flicker speed or is faster than the length of the individual flash of light. or group of flashes. The flicker goes away if the operator lengthens the shutter opening. That means when working with LED lights, the camera person has to keep the shutter speed fairly slow and this reduces his/her options, as the aperture must therefore be reduced to compensate for the longer exposure.

Professional film/video cameras have built-in physical ND (neutral density) filters that allow the operator to bring the shutter speed down to around 60 and still open up the aperture for a shallower depth of focus. You can also buy ND filters to put over the lens.

There are plugins available that can eliminate flicker in your editing software. I know that the latest version of Vegas Pro has one and I'm sure others are available.

Re: Zoom Q2n video flicker fix?

PostPosted: Wed Oct 14, 2020 10:07 am
by Mike Stranks
The Red Bladder wrote:I do not know the Zoom Q2n but the answer is always and only 'shutter-speed'.

Set the shutter speed to a slower setting and the flicker goes away.


Errmm... this is a Q2n. You can select different scenes, but that's it!

O/P: have you tried experimenting with different scenes or capture formats?

Re: Zoom Q2n video flicker fix?

PostPosted: Wed Oct 14, 2020 11:49 am
by MOF
It’s best to match the camera frame rate and electric mains frequency when you’re dealing with artificial lighting. If you have any light source in shot, including tungsten, that doesn’t match the camera’s frame rate then you will see it flickering or slowly fading up and down. Reflected light you normally don’t see that, because, like when sound reverberates the initial sound waves arrive back at your ears at slightly different times.
The electronics that control some led lights are made down to a price and do not have a fast enough refresh frequency and aren’t matched to a suitable ratio of the mains frequency. To match these you need a continuously variable shutter speed to stop the strobing before it gets to the sensor which samples at typically 25 or 30 frames per second.

Re: Zoom Q2n video flicker fix?

PostPosted: Wed Oct 14, 2020 1:01 pm
by The Red Bladder
The plug-in that cures this is called Flicker-Free and costs $129 RRP. Make sure it works for the editing system you are using.

DaVinci-Resolve has a de-flicker function but it requires considerable processing power - but as the programme is free, worth a stab.

If there is not too much motion in the footage, try placing a second copy on the timeline and doing on overlay, but moving the footage one frame to the right or left (mute the second audio of course!) This is however a real bodge in most cases!

The problem with these Zoom things is that they create more problems and costs than they are worth. Buying a decent bridge camera like the Panasonic FZ1000 (I have two and they're great) gives you zoom, 4K video, audio in, and you can adjust any and all settings from aperture to shutter speed and even do slo-mo. Used they go for under £300 and I snaffled mine new (shop returns) for £300 plus VAT.

I have magic cameras for film, but for quick-n-easy run-n-gun, the FZ1000s are my go-to toys.

Blowing about £200 on something that is close to useless unless it is used outdoors, has a screen too small to see, and prevents the user from being able to set normal stuff like shutter speed and aperture does not make any sense to me. They are supposed to be used for quick band demos, but can't be used with modern stage lights - the words 'utterly useless' really do spring to mind!

Re: Zoom Q2n video flicker fix?

PostPosted: Thu Oct 15, 2020 2:05 pm
by jhmax
Thanks for the info guys, The Q2n has its uses (and decent sound) as well as its limitations , and at the £85 new this one cost (it was superceded by the 4K), it's not much of an investment for trying out AV. I'll try some brighter tungsten lights - the tungstens in that room are very dim, which may make the flickering worse when the LEDs are off.

Re: Zoom Q2n video flicker fix?

PostPosted: Fri Oct 16, 2020 10:17 am
by maxed
Problem fixed - restecp to those who said 'try tungsten lighting'! A 500w workshop tungsten inspection lamp hung overhead produced an acceptable live flicker free webcam image from the Q2n with the usual good quality (for the price) sound. Now I need a powerful clip on tungsten lamp that won't kill me if it falls off the beam I hang it on. I'll sort out the suntan later... Max

Re: Zoom Q2n video flicker fix?

PostPosted: Fri Oct 16, 2020 10:48 am
by blinddrew
:thumbup: