96fps flicker with indoor lighting. Thoughts? at DVinfo.net

Chad Hucal · July 22nd, 2014, 07:14 PM

I've been experimenting with my new GH4 and found this little problem today. I've tested 96fps outside in daylight and didn't get this issue.

The particulars;

- System Frequency - 24.00Hz Cinema
- Format - .mov
- Rec Quality - 1080p/100mbps

I've linked the footage I shot below. There are three clips. The first has the variable frame rate turned off, the second has it turned on and 60fps is selected, the third is 96fps. Only the 96fps showing the flicker.

There are two light sources in the bathroom, mostly halogen bulbs, but the second source behind the camera is fluorescent. Maybe one of these lights is making the flicker occur.

Password is: test

Is there another in-camera setting I can select to match light source frequency?

William Hohauser · July 22nd, 2014, 08:22 PM

The fluorescent lights are the source of the flicker. They flicker at sixty cycles which creates an interference pattern with the 96fps. You are capturing the times the bulbs are momentarily off.

Bruce Watson · July 23rd, 2014, 10:08 AM

Quote:

Originally Posted by Chad Hucal

I've linked the footage I shot below. There are three clips. The first has the variable frame rate turned off, the second has it turned on and 60fps is selected, the third is 96fps. Only the 96fps showing the flicker.

Mains frequency in NTSC land is 60 Hz. To avoid flicker, you need a frame rate / shutter speed that is an even multiple of mains frequency. So, a frame rate of 30, 60, 120, etc. Or... you need lights designed for this duty. Building fluorescents won't cut it, but Kinoflos will, as will other cinema lights.

Just sayin', you gotta use the right tool for the job.

Chad Hucal · July 23rd, 2014, 12:02 PM

Thanks for both of your input.

I wasn't using the bathroom as an actual filming location, I was just mucking around in different rooms of the house trying out different lighting situations. Most anything I film will be under real world lighting conditions so I won't ever really have special lighting. If I ever have a proper studio space, yes, I'll have proper lights. But for now I'm just trying to learn how to use the camera in everyday situations.

Hopefully the info gathered in this thread will help others going forward too (at least others like me who are still learning stuff).

I just went back are set up that shot again. Still on 96fps and using the last shutter speed from yesterday I got the flicker once again (obviously). I then lowered the shutter to 125, and there was no flicker during recording or playback.

So without proper cinema lights I guess it just takes some adjusting to find the right flicker free image in certain conditions. I assume the same can be said if trying to film with a computer screen or TV on in the image, to get rid of the flicker some frame rate or shutter speed adjustments need to be made.

If anyone has tips for filming under these conditions, please add them.

July 22nd, 2014, 07:14 PM	#1
Chad Hucal Regular Crew Join Date: Jun 2008 Location: Vancouver, Canada Posts: 77	96fps flicker with indoor lighting. Thoughts? I've been experimenting with my new GH4 and found this little problem today. I've tested 96fps outside in daylight and didn't get this issue. The particulars; - System Frequency - 24.00Hz Cinema - Format - .mov - Rec Quality - 1080p/100mbps I've linked the footage I shot below. There are three clips. The first has the variable frame rate turned off, the second has it turned on and 60fps is selected, the third is 96fps. Only the 96fps showing the flicker. There are two light sources in the bathroom, mostly halogen bulbs, but the second source behind the camera is fluorescent. Maybe one of these lights is making the flicker occur. Password is: test Private Video on Vimeo Is there another in-camera setting I can select to match light source frequency?

July 22nd, 2014, 08:22 PM	#2
William Hohauser Inner Circle Join Date: Dec 2005 Location: New York City Posts: 2,650	Re: 96fps flicker with indoor lighting. Thoughts? The fluorescent lights are the source of the flicker. They flicker at sixty cycles which creates an interference pattern with the 96fps. You are capturing the times the bulbs are momentarily off. __________________ William Hohauser - New York City Producer/Edit/Camera/Animation

July 23rd, 2014, 12:02 PM	#4
Chad Hucal Regular Crew Join Date: Jun 2008 Location: Vancouver, Canada Posts: 77	Re: 96fps flicker with indoor lighting. Thoughts? Thanks for both of your input. I wasn't using the bathroom as an actual filming location, I was just mucking around in different rooms of the house trying out different lighting situations. Most anything I film will be under real world lighting conditions so I won't ever really have special lighting. If I ever have a proper studio space, yes, I'll have proper lights. But for now I'm just trying to learn how to use the camera in everyday situations. Hopefully the info gathered in this thread will help others going forward too (at least others like me who are still learning stuff). I just went back are set up that shot again. Still on 96fps and using the last shutter speed from yesterday I got the flicker once again (obviously). I then lowered the shutter to 125, and there was no flicker during recording or playback. So without proper cinema lights I guess it just takes some adjusting to find the right flicker free image in certain conditions. I assume the same can be said if trying to film with a computer screen or TV on in the image, to get rid of the flicker some frame rate or shutter speed adjustments need to be made. If anyone has tips for filming under these conditions, please add them.