GH2 Slow motion with Flourescent lights and a Rolling shutter?

M

mpgxsvcd

Veteran
So how you all deal with shooting at faster shutter speeds in fluorescent lighting with a rolling shutter camera. I shoot a lot of slow motion indoors and so I want to shoot at higher shutter speeds. However, I get a sort of strobing affect if I go faster than 1/120th of a second.

Will this make 120 FPS useless for these types of shots in florescent lighting?

Here is an example of what the indoor slow motion looks like with 1/120th of a second shutter speed. I tried it with 1/250th and it puts a black bar through the video that I presume is from the rolling shutter.

This was shot with the 25mm F1.4 and 720p @ 60 FPS with 1/120th shutter speed. It is simple slowed down video without any use of an interpolating program like Twixtor.

 
Consumer and commercial fluorescent lighting pulses, to get around this you have to use a different light source. Places that rent real high-speed cameras like the Phantom also rent high-speed lighting to use with it because of the strobing issue.
 
TheDingo said:
Consumer and commercial fluorescent lighting pulses, to get around this you have to use a different light source. Places that rent real high-speed cameras like the Phantom also rent high-speed lighting to use with it because of the strobing issue.
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Can you use that specific lighting with the fluorescent lighting in place or do you have to turn off the fluorescent lighting as well?
 
mpgxsvcd said:
Can you use that specific lighting with the fluorescent lighting in place or do you have to turn off the fluorescent lighting as well?
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It's of no use if the light is pulsing at the frame rate you are shooting at. ( unless you want that look )

The cheapest solution is to use tungsten. For the DefyGravity shoot above, I would consider rigging a whole bunch of Lowel Tota-lites to the walls or ceilings. It would take some effort to rig the lights, but it would be very bright with good color. ( high speed video requires very bright lighting )
 
I don't have a suggestion for your question, but wanted to tell you I liked the video and I don't see any strobing in it. I imagine a more "professional" look with a lot better lighting and more frames per second, but I'd be happy with your effort when I do this with my family... Al
 
aljudy said:
I don't have a suggestion for your question, but wanted to tell you I liked the video and I don't see any strobing in it. I imagine a more "professional" look with a lot better lighting and more frames per second, but I'd be happy with your effort when I do this with my family... Al
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Thanks. I realize that most people here shoot most everything with controlled lighting and in situations where they can do multiple takes. However, for shooting sports like this you really can’t control the situation.

There wasn’t any color grading or real editing done for this video. There really wasn’t a huge need for it. I simply just recorded as many clips as I could in 1 hour and then pieced them together to fit with the music.

Videos like this would probably still get the point across even with a lesser camera. However, it is nice to be able to shoot relatively high quality video without much effort and with as little impact to the action or venue as possible.

One of the workers that was in the video had no idea I was filming him and I was right next to him. If I had a huge external lighting system I guarantee he would have noticed it and probably asked me to leave. Instead he seemed to think it was a cool promotional video for the gym.
 
TheDingo said:
Consumer and commercial fluorescent lighting pulses, to get around this you have to use a different light source. Places that rent real high-speed cameras like the Phantom also rent high-speed lighting to use with it because of the strobing issue.
Click to expand...

Wow I just looked up how much it would be to rent a phantom! $3000 a day just for the camera body alone. Nothing else. That thing has produced some of the best footage I have ever seen(Shark Week) but its price reflects how good it really is.
 
mpgxsvcd said:
Can you use that specific lighting with the fluorescent lighting in place or do you have to turn off the fluorescent lighting as well?
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The fluorescent lighting is going to interact with the camera's shutter no matter what. You could only use them together if the continuous lighting totally overpowered the fluorescent, but in that case, what would be the point of having the fluo at all?

A continuous light source (such as tungsten, or an extremely high-frequency fluo or HMI) will output a basically continuous wave of light that won't be affected by the rolling nature of the CMOS shutter. But a discontinuous, sine-wavy light source like a typical 60Hz fluorescent is going to be putting out different levels of illumination constantly, and our eyes don't see it, but the high speed shutter of the camera definitely sees it.

Rolling shutter cameras + high-speed shutters + low-refresh-rate fluos or HMIs = banding. No ifs, ands, or buts. Only way to avoid it is to use a shutter speed that is an exact divisor of the power frequency (so, for a 60Hz camera, that means 1/60, 1/40, 1/30, or 1/24; you can frequently get away with 1/120 as well). But no faster; 1/200 and above are definitely visible banding territory. And 1/50 is bad too! There's visible banding under 1/50, but not nearly so visible as under 1/100, or 1/200 or faster.
 
Barry_Green said:
The fluorescent lighting is going to interact with the camera's shutter no matter what. You could only use them together if the continuous lighting totally overpowered the fluorescent, but in that case, what would be the point of having the fluo at all?

A continuous light source (such as tungsten, or an extremely high-frequency fluo or HMI) will output a basically continuous wave of light that won't be affected by the rolling nature of the CMOS shutter. But a discontinuous, sine-wavy light source like a typical 60Hz fluorescent is going to be putting out different levels of illumination constantly, and our eyes don't see it, but the high speed shutter of the camera definitely sees it.

Rolling shutter cameras + high-speed shutters + low-refresh-rate fluos or HMIs = banding. No ifs, ands, or buts. Only way to avoid it is to use a shutter speed that is an exact divisor of the power frequency (so, for a 60Hz camera, that means 1/60, 1/40, 1/30, or 1/24; you can frequently get away with 1/120 as well). But no faster; 1/200 and above are definitely visible banding territory. And 1/50 is bad too! There's visible banding under 1/50, but not nearly so visible as under 1/100, or 1/200 or faster.
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Thanks for this info. The only reason to use both types of lights would be if the gym couldn't or wouldn't turn them off. They might allow me to have some dedicated lighting in a certain section. Perhaps those lights could over power the fluorescent lights enough to allow me to use very fast shutter speeds?
 
If the gym overheads are what's causing the problem, and you put a big tungsten unit close to your subject, I would guess that it would certainly overpower the overheads. Maybe stuff in the background would still have rolling bands though. Anything that's lit by the fluorescents will have rolling bands.
 
Barry_Green said:
If the gym overheads are what's causing the problem, and you put a big tungsten unit close to your subject, I would guess that it would certainly overpower the overheads. Maybe stuff in the background would still have rolling bands though. Anything that's lit by the fluorescents will have rolling bands.
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Absolutely correct, I filmed a controlled, Arri light kit subject with a couple of fluorescents that were very high... like 20ft as very little fill for a black-ish background, and the background had those feint rolling shutter lines, ugh!

On another shoot where I had to rely on fluorescents, I ran a 60 shutter speed and did not have those issues. THANK YOU DVX USER for that info BTW!!
 
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