Lighting issue (wavy lines)

C

CrackDown

Member
I just finished a short film and we had some dark scenes that were lit with a 126 LED portable light. Some of the shots, if not all of them have wavy lines similar to the ones seen in this video at 8secs onwards http://www.youtube.com/watch?v=akyzgQY-9us

I've just tested it again with different shutterspeeds and they never go away no matter what. I was shooting PAL at 50fps. Anyone have any ideas? Unfortunately it'll be difficult for me to reshoot the material I already have, so is there anyway I can get rid of this in post?

Thanks
 
I have had this same problem when shooting under very bright LED lights. I did one shoot for a band where all of their stage lights were LED and i had this banding problem. I found that dropping the shutter speed as low as i could. For me shooting 24p it was 1/30th. That helped to reduce that banding as much as possible. now i have to figure out a creative post solution for this.

If your in final cut you can take a look at this solution
http://filmmakeriq.com/2010/07/how-to-remove-horizontal-band-lines-from-dslr-footage/

For me in premiere its a little harder to deal with.
 
The LED lights are pulsed, it could be at any rate.
You need to match your shutter speed to the LED pulse rate in the same way you would match your shutter speed to the scan rate of a computer monitor when shooting computer screens
 
No way to get rid of it in post.

As for cause, what was your shutter speed? It needs to stay at 1/50 (if shooting in NTSC territory, 1/60) to match the electrical system of your country. You'll see that kind of artifact when shooting under florescent lights with the wrong shutter speed, too.

LEDs can be a different issue, though. Dimmable LEDs especially can cause those problems even at the proper frame rate.
 
Thanks for your replies. I tested a load of shutterspeeds and it never fixed it. It is a dimmable LED light, so I presume this is just an inherent problem with them. I had to go and buy a flourescant and reshoot the scenes :/
 
I ran into this with some 500W shop lights I was using to light something as well. Played with the shutter speed and couldn't make it go away. I try to avoid those lights now.
 
the 126 led might have a faulty modulator for the dimming
turn to highest setting me let it go away
or the battery voltage might be low
or hit and shake it, it might work properly again... (what i did to mine)

or its just your house light that flickering
in US and Canada, you have to use 50 or 60 shutter to avoid it
 
CrackDown said:
Thanks for your replies. I tested a load of shutterspeeds and it never fixed it. It is a dimmable LED light, so I presume this is just an inherent problem with them. I had to go and buy a flourescant and reshoot the scenes :/
Click to expand...

Stop using cheap underpowered batteries. Go and buy some AA batteries that are rated for the highest digital equipment you can find...... You can thank me later as your problems will disappear........
 
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