How do I fix filming at night?

Lower the shutter speed to 1/125 and you will be golden.

I don't think thats the problem at all.. its like the frequency of the lights wasn't 60hz...

It is the frequency of the lights (60 Hz in the USA, 50Hz in Europe) interfering with the frame rate of your camera (60 Hz).

Try setting the camera to 50 Hz or changing the shutter speed.

I used to have this problem all the time with my D5000 which is fixed at 24 fps.

So you are saying dont shoot in 60fps?

Nope, just lower the shutter speed to 1/125. Were those lights powered by generators?

yes they were. wont 1/125 not capture the riders cleanily and will cause ghosting?

I don't understand why the frequency of the light can be affected by shutter speed. Is there some reading I can do on this somewhere?

Motion blur but not ghosting. I like the look, some people don't. For some odd reason the generator could have had a 50hz output which could have caused dome problems. Usually going higher than the 180 rule (for 24p at least) just causes some banding, i would expect the same for 60p. In your case it gave some funky ass lighting, i would post this on cinema 5d or some other camera forum.

Think of it as trying to sync up the time that the shutter is open and the time that the light is active. If you use a very fast shutter speed, you will generally be more likely to have this banding type effect (which I believe is a factor of how the camera captures the pixels, top to bottom or vice versa, not sure though) since you will be capturing less of the flicker.

Alternating currents are sinusoidal, so the light smoothly goes from on to off (more or less, depending on the type of light). If it just so happens that you have a fast shutter speed, which is timed such that the shutter captures only when the light is at a minimum, the scene will appear dark relatively dark compared to if the camera frame rate and light source are in phase with each other.

If there are differences in the frequencies, then there will be a frequency (equal to the difference between the two, if I recall correctly) of light "flickering" on and off.

By using a slow shutter speed, you will tend to have a greater range of the alternating light source showing up in each frame. It takes more of an average of the light source. By slowing your shutter speed to match your frame rate (ex. 1/60 sec for a 60 fps video, or 1/30 sec for 30 fps video), there should not be any noticeable lighting change from one frame to another since it will take an average of the light over an entire phase (such as maximum, to minimum, and back to maximum).

Hopefully this is easy enough to understand, and I didn't butcher the technical details too much.

I'm sorry but not only is this terrible advice, but its is completely wrong.

Never go below the 180 rule. 24p should be 1/48 at the least, 30p 1/60 at the least, 60p 1/120 at the least.


The lights are flickering because of the frequency. Why big sky had non 60hz frequency lights is beyond me, but thats the problem.

its not shutter, its frame rate 60hz (america and canada?) 24p and 60p while 50hz (europe) 25p and 50p. If you have the wrong frame rates, you get this kind of flashing. You can see this in some ski movies, level 1 hit some huge blue dub kink a few years ago in europe and the lights are flashing because theyre 50hz and theyre shooting 24p/30p/60p

I agree with you about never going below the 180 rule but I think he was more just explaining the concept and not addressing the OP's original post

He tried to say lowing your shutter to the same as frame rate (ie 30p and 1/30) would eliminate this problem which is completely false.

haha alright disregard my post then. Honestly i'm not sure how it works but after reading what he wrote it seemed to make some sense so I'm curious what would cause the light to flicker like that/how to fix it

read my previous post

missed that post. Well i know the answer now but it still makes zero sense why it would cause it. not a big deal because I'm guessing i'll never run into this problem

F/9.0? YOu should be shooting at like F4 for video at night...

No because not everything is about bokeh. And it was a contest so i cant quickly change my focus.

Anyways just dropped my shutter speed down tonight and used the minimum 180 rule and it worked perfect. Thanks guys.

fucking work with it. Make some flashy light effects or something i dunno

hmmm.. that doesnt make any sense...

what lights were they using?

Tall construction type 4 light towers that are straight connected to generators. ill see if I have a shot of one.

Hmm... ive shot urban with studio lights at 1/250 and 1/250 like under other lights too and never had the problem but the construction lights must be slower or something?

F9 seems crazy. What ISO have you been shooting?

1600 anything past that gets really grainy but 1600 stays pretty clear. I shot some at 800 though.

and they were using 4 of these

Next time open it up to at least 5.6. I bet you could get a much less grainy image.

at 5.6/4 you can still be a certain distance away and have everything in focus, its called the hyperfocal distance, google it

I mean I wasn't finding it too grainy

You could eliminate all grain if you just shot f4

Will do that next time. Thank you for the tips guys!

I should have been more clear in my post: I was not recommending that he adjust it to below the 180 rule. The 180 degree rule is a matter of human perception and aesthetics. I was simply describing the mechanics at work, and using that as an example. And as far as the mechanics go, what I said is valid.

These types of things are common problems that are faced by many people outside of the videography/cinema industies as well. It has been an issue at my place of work where we needed to capture data of high frequency oscillations. The sampling rate had a significant effect on the results. The only aspect of the video camera system I am unsure of is the operation of the rolling shutter, and how it will play into the equation. I suspect it is actually this effect that causes the greatest contribution to the banding you see, as there it actually takes the camera a very short time interval to scan across the sensor during which time the lighting conditions may have changed.

I suggest you try it out for yourself. You will notice how the effect is much more dominant at higher shutter speeds, and less so at lower shutter speeds.

From what I took away from Dustin's post, he was just wondering why shutter speed had an effect. For future reference, it is generally called undersampling.

If you work with video cameras or plan to work with video cameras or other sampling systems as a profession, I strongly recommend learning about as much of the physics behind the systems as possible. It can't hurt.

No need to get carried away, now.

Like I said, I've shot in many different lighting situations at 1/180 and 1/250 shutter and never have had the problem in OPs video.

I rarely shoot at the 180 degree rule, im usually at 1/180 or 1/250, the main thing i was against in your post was suggesting shooting 30p at 1/30 and 60p at 1/60.


I understand how it works, i'm just saying that flashing usually only occurs with different frequencies of light. I dunno if its different with dslrs, i dont use a dslr though.

Also, as for your comment ("He tried to say lowing your shutter to the same as frame rate (ie 30p and 1/30) would eliminate this problem which is completely false."), I took this as a point you were strongly disagreed with, though I see no reason as to why I was completely wrong. For anyone who is actually interested, I suggest looking up credible sources on this. Internet forums are only a starting point -- I cannot stress this enough.

What has not been mentioned in this thread is the type of light used. Many types of lights operate such that the light's output is not directly proportional to the current passing through it / voltage across it. The easiest example to think of for this is an incandescent bulb which heats a filament to produce the light. This heat does not significantly depreciate from one cycle to another, and correspondingly neither does the light. The light output will therefore be smoothed from one cycle to another, the amount by which depends on the light itself. If you were to use a light which has a similar effect, then the flicker would be greatly reduced or entirely unnoticeable, regardless of shutter speed or frequency mismatches.

To see something representative of what the light output is doing during this time, compare these two plots, paying attention to the scales on the y-axes: http://www.wolframalpha.com/input/?i=plot+abs%28sin%282*pi*60*t%29%29+t%3D0..%281%2F60%29*4 and http://www.wolframalpha.com/input/?i=plot+%280.9%2B0.1*abs%28sin%282*pi*60*t%29%29%29+t%3D0..%281%2F60%29*4
Each one is a plot of four cycles of AC power at 60 Hz. The first one has a +/-50% flicker whereas the second one is smoothed out at a higher light output, with only a +/-5% flicker (which I chose arbitrarily). The actual % flicker will depend on the light itself, and the frequency at which the voltage is applied across it. (Wolfram Alpha tends to shorten the axes, which is why the second one looks so similar.) Note that the curves are actually a plot of the light output, which is why they have points at the bottom, unlike the voltage which actually does have a smooth sinusoidal shape.

If you find you are having problems with these bands of light/darkness (which means that you have a frequency mismatch) and want to have flexibility of frame rate and shutter speed, you may want to consider trying out a filament-based light (likely one which gets quite hot). That way you can continue using the same camera settings and generator.

Not that I'm saying Wikipedia is a credible source, but here is a little description on the banding effect in relation to fluorescent lights: http://en.wikipedia.org/wiki/Fluorescent_lamp#Flicker_problems
It even mentions that there are fluorescent lights that use electronic ballasts which create a flicker at 5kHz, which I was unaware of. With lights such as that, you should not notice any flicker in your video unless you are shooting at above 5000 fps (or with a shutter speed faster than 1/5000 sec, I believe).

Again, anyone feel free to correct me if you can prove that I am wrong. It's in everyone's best interests if you can provide a valid explanation, and not just your own opinion on the matter.

this > eheaths explanation

I don't get what you are trying to prove? I mean anything over like 1/200 of a second i got flicker.

I'm saying that if you use a light which uses a heating of a filament to generate the light (or something with a more steady light output), then your flickering problems should be solved at any frame rate or shutter speed.

The problem is that these lights do heat up quickly, but you can look into similar options. That will let you keep using the same generator as well (which I assume will be the larger cost). If you have a generator which has an output that sync's up with your frame rate well, then it wouldn't be a problem. But it apparently is since you do have some banding.

More than anything, I was just trying to explain what is actually going on with the problem, and potential ways around it.

Rob explained it better than i ever could. Great explanation!