High speed & flicker

D

dmitrizigany

Veteran
Hey!

Since I got my FS700 over a year ago, I have almost never used one of it's key features; super slow motion.
one reason is I almost never film in daylight, and the few times I've tried it, I've got flicker.
I bought a pair of fresnels cause I read that tungsten was flicker free, but I still got flicker, so then I read that apparently if they are not strong enough, you still get flicker. Mine has only 300W bulbs in them but can hold 650W. Would that help?

What would be the best solution to get a functioning light kit (let's say 3 lights) that is guaranteed flicker free? On a budget ;)

Thanks
 
dmitrizigany said:
I almost never film in daylight, and the few times I've tried it, I've got flicker.
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Not sure how you got flickering when shooting outside, but the Sun is pretty much the only light source that you can guarantee WON'T cause flickering. Generally Fluorescent banks like the Kinoflo Diva (or the like with a 'High Speed / Flicker Free Ballast') are pretty safe to use. LED panels are usually as well. Tungsten lights greater than 2k are usually safe. 1k's are less safe and under that you'll most likely see flicker. I wouldn't count on a 650w tungsten fresnel to be flicker free. HMI's will depend on the quality of the ballast. Some of the better electronic ones will probably be able to do 200 FPS no problem as long as you are careful with your shutter speeds.

There have been lots of tests done online. Just google something like 'Flicker FS700' and you should get a few video hits on the tests.

'On a budget' will completely vary from person to person, so you'll have to let us know. The cheapest would simply be shooting outside (free).

Large Tungsten fixtures like a 2k blonde probably would work well enough for 200 fps and can be had for less than $200 a piece. However, powering a couple 2k blondes is another issue...

LED panels like the F&V k4000's are what I'd be looking at. Daylight balanced and are $300 - $400 apiece. Cheaper lower power panels might not flicker, but keep in mind you also need quite a bit of light to shoot at higher frame rates.

Chinese Flourescents 55w biax's can be found for pretty cheap online - $200 or so. Any decent one shouldn't have flickering problems unless you try to dim the tubes.
 
Quick tip ...

Wack the flickering file in to your NLE timeline. Drop the same clip underneath it so they are layered. And then change the framerate by 1 on one of the clips and watch the magic unfold in front of your eyes.

It's worked for me a few times.

Alternatively, buy LED light panels instead of Tungsten.
 
CinematicFanatic said:
Quick tip ...
Wack the flickering file in to your NLE timeline. Drop the same clip underneath it so they are layered. And then change the framerate by 1 on one of the clips and watch the magic unfold in front of your eyes.
It's worked for me a few times.
Alternatively, buy LED light panels instead of Tungsten.
Click to expand...
I've tried that actually and it worked fairly well. Just felt there was a bit of quality loss regarding picture. And would be nice to get it working without workarounds.
 
Strouty said:
Not sure how you got flickering when shooting outside, but the Sun is pretty much the only light source that you can guarantee WON'T cause flickering.
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That was bad phrasing from me, meant to say "the few times I've tried it inside (with lights) I've got flicker".

Thanks for the write up!

Interesting, I thought Florescents were a definite no-go. I want to get some LED panels anyway, so maybe that's the route, and hope for the best ;)
 
i got great results with 1K and 2K tungsten fresnels, as well as the four bank kinoflo divas mentioned above. led's work as well. to prevent flicker 100fps is usually save in pal land and is my go to alternative if i can not control the lighting...
 
Shutter speed is important as well, if I shoot with tungsten lights at 100fps I set shutter speed at 1/100, if its any faster you will most likely get flicker. At 200fps pretty much will have flicker with tungsten lights no matter what.
 
dmitrizigany said:
I've tried that actually and it worked fairly well. Just felt there was a bit of quality loss regarding picture. And would be nice to get it working without workarounds.
Click to expand...

Even softwares/plugins that get rid of flicker are basically doing the same trick to the file.

Which NLE are you using? I use Vegas and there isn't any quality loss at all. Your using the first track with "screen or add enabled" forgot which one so it basically ghosts itself on top of the second track.

It's been a life saver for me.
 
Flicker is a feature of alternating current. If you want to avoid it use DC sources - which basically means LEDs or plasma sources these days (although the cheap ones actually 'dim' by flickering so if you have a cheap LED panel that flickers at high speed just whack it up to 100%) I know the Ayden Tech units boast flicker free performance at 1,000,000 fps.

Regular HMIs tend to be okay up to a couple of hundred fps, after that you need a high speed ballast (which Are flicker free up to 1000fps) film fluorescents (e.g Kinos) are generally okay to 5,000 fps. As regards tungsten units the issue is that the smaller the element the quicker it heats up and cools down as it goes through the AC cycle. Which basically means the bigger the lamp the faster you can go without flicker. I've had issues at 240fps with 1Ks, but found it okay with 2ks and I've had no problems at 1,500 fps with 5Ks and 10Ks.
 
CinematicFanatic said:
Which NLE are you using? I use Vegas and there isn't any quality loss at all. Your using the first track with "screen or add enabled" forgot which one so it basically ghosts itself on top of the second track.
Click to expand...
Yes, and it's that ghosting that should lead to some degradation. Since it will be overlapping two different frames that should mean the picture gets softer/blurrier. Haven't really tried out that theory though. Only used it ones and it made the footage usable so that was good. But would probably have been even better if it was flicker free to start with :)

I'm using FCPX.
 
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