Emergency Question! (Rolling Shutter & Flashing Lights)

I

Indyreel

Well-known member
I have a huge scene with emergency vehicles (police and fire) tomorrow!

Thier emergency lights will be flashing away all over the place for the scene.

But...

I noticed tonight, when doing some practice footage that flashing lights freak out the GH1 sensor, causing vertical banding all over the place.

Is there any way to stop this???!!!!!!!

Please help.
 
hmm I'm not aware of this that you speak of. are you sure about this and where did you obtain this information that flashing lights 'freak out the sensor' ?
 
one of the top guys here, is it Barry Green I can't remember has shot a professional quality footage film here on gh13 I remember it's floating aroudn somewhere, it is a dark low light scene outside with a police car and other vehicles with flashing lights and his scene came out fine
 
Homunculus said:
hmm I'm not aware of this that you speak of. are you sure about this and where did you obtain this information that flashing lights 'freak out the sensor' ?
Click to expand...

I'm seeing it right now. I turn on my strobes and film in that direction and the camera gets horizontal lines all over the place.
 
The split frames you're seeing is due to the CMOS sensor.
CMOS uses a rolling shutter (as opposed to a global shutter) - meanign it reads the frame sequentially from top to bottom, instead of all at once. When strobes, flashes, or anything else is moving faster than the time it takes the camera to read the entire frame you wind up with split frames like you saw from the lights. Rolling shutter is the same thing that causes the jello in some footage - or the diagonal leaning you'll see in quick pans.

It is one of the limitations of the technology, and as far as I know there isn't much you can do about it.
Hopefully someone else will pipe up with some knowledge about how to lessen the chances of it causing an issue for your particular shoot.
 
Indyreel said:
I'm seeing it right now. I turn on my strobes and film in that direction and the camera gets horizontal lines all over the place.
Click to expand...
Yep, that's what happens when you use a CMOS rolling-shutter camera. And no, there's not a thing you can do about it. Unless you want to go through in post, for every single flash frame, and try to correct for it.

CMOS isn't good for that kind of shot.
 
What about the 720p60/50

What about the 720p60/50

Itook some footage at a fair-fairground and things were flashing all over, strobes etc, not a single problem in 50p?

Be interested in your results?
 
same here. I was at a state fair with flashing things all over the place and I saw no problem in my footage. Does anyone see any problem with http://vimeo.com/10512682 at the 54 minute mark that I'm missing because it looks great to me.
 
since the lights will be bright and distracting anyway, why not just rent/borrow/steal a CCD camera for those shots and cut it in?
 
Homunculus said:
same here. I was at a state fair with flashing things all over the place and I saw no problem in my footage. Does anyone see any problem with http://vimeo.com/10512682 at the 54 minute mark that I'm missing because it looks great to me.
Click to expand...


Thats because those are rotating lights, not flashers.

the flash rate for solid state lights(LEDs) is much faster than the shutter of a CMOS camera and therefor looks like blocks of washout where a rotating light is ramping up/down in brightness much more slowly.
 
Doesn't 60p mode have a faster CMOS refresh rate? I'm pretty sure the 60p mode of the Canon's has a faster refresh rate... so maybe try that?
 
Svart said:
Thats because those are rotating lights, not flashers.

the flash rate for solid state lights(LEDs) is much faster than the shutter of a CMOS camera and therefor looks like blocks of washout where a rotating light is ramping up/down in brightness much more slowly.
Click to expand...
ah ok...well you could get a cop car with rotating lights rather than flashing ones then for your shoot = problem solved
 
I've had this problem with flash photography. If the light is far enough away no problem, when it is right there it isn't good.
 
good god. panasonic is lucky no one showed me those pics before i bought my gh1 otehrwise I would never have been a customer lol!
my 50$ cell phone camera takes better pics
 
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