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  • Hey all, just changed over the backend after 15 years I figured time to give it a bit of an update, its probably gonna be a bit weird for most of you and i am sure there is a few bugs to work out but it should kinda work the same as before... hopefully :)

how to light at 300FPS??

I often use DC power when shooting High Speed. No Flicker. Tungsten lights. Maxis, 20K's, Mole Beams. Parcans, Etc.


B Jonsson
 
Shooting High Speed is a sub category in it's self. There are lots of things to learn. I used to own a bunch of Photo-Sonics cameras and shot a lot of high speed. It's not something you can just go and do and expect it to turn out OK. You need to learn all the rules and the theory. Reading the ASC manual is a good start.

Nick
 
+ 1 to all of the above. I have a friend who's made a living shooting ultra high speed. Do be careful when using hotter lights closer to your subject. He showed me some lovely pictures after capturing a strawberry dropping into cream where the bucket of cream melted and spilled everywhere.

I've done a smidgen of this type of work myself. Not all light sources flicker. Experiment, test, then shoot the big day.
 
300fps isnt too onerous.
Electonic ballast HMI lamps are meant to be flicker free but often they aren't.
Often the edges of the beam flicker.
AC powered continuous source (tungsten) are generally ok for 300fps.
But sometimes thin filaments in domestic bulbs cool down between 50hrz or 60hrz beats and create a flicker. I have only come across this once, whilst shooting in the Capitol Hill building at 25p and 1/60th shutter.
DC power, if not screwed up by a rectifier, is a safe bet.
BTW if you come unstuck there are software tools that auto grade interframe differences in brightness and contrast.
To estimate how much light you need consider that the frame rate is the lowest shutter speed you can run. So if you can shoot 1/300th second at x aperture at 24fps you can shoot 300 fps with an open shutter at same aperture.
So 300fps needs 3 or 4 more stops, not a problem for tabletop.

Generally choice of shutter speed calculated as double the frame rate is a good starting point for slomo although this is subjective and the higher the frame rate the more we tend to be shooting very high speed objects where insanely high shutter speeds are useful.

Slow motion shooting and instant replay is a marriage made in heaven.


Mike Brennan
 
Things to consider:
Use tungsten lights if possible.
As mentioned, tungsten lights can also flicker (slightly). But with larger heads (>5kw) the bulbs and their filaments are bigger and the risk of flicker is less.
Or use several smaller heads as one source and power them from different phases from your power outlet.

Joost van Herwijnen
 
Tungsten lights bigger than 5K (maybe better 10-20K - 5K can flicker depending on the lamp/filament age) are pretty save, but there may be some more noise in the image (at least with digital cameras). When powered with DC source also smaller lights work safely.

HMI lights do normally flicker at 300fps. There two ways to solve the flickering:

1st with the trick mentioned above: Combine 3 heads to one source (through a Diffusion Grid) and put each head on a different phase. Flickering of each single lamp will be elimanate by one of the others in 95% using the trick. But always test this, especially if you´re doing it for the first time.

2nd: There are special modified "Digital Highspeed ballasts" (http://www.arri.com/lighting/lighting_emea/ballasts/high_speed_ballasts.html). From 1,2K to 4K their running at 1000Hz - and you will have no problem at all. 6K or bigger will run at 300Hz - which will still be ok for 300fps (could be some problems with very high framerates above 600fps). But these ballasts are not available everywhere - ask you´re rental house beforehand.

When testing lamps before you´re shooting, you can see if there´s any flickering instantly when doing a playback (when shooting digitally) by looking at the waveformer on your monitor. If there´s anything moving up and down constantly, it´s most probably a flicker problem. One better way to test it: Spot the lamp on a white wall, record a sequence and playback it. You´ll see any flickering instantly (mainly on the edges of the spot).


Johannes Knaupp
Highspeed Supervisor & Developer at Weisscam
 
Mitch Gross said:
I wrote about lighting for High Speed a while back in reference to Phantom cameras. Check the bottom of this link:

http://multi.abelcine.com/resources/2009/06/18/phantom-hd-faqs/
Click to expand...

In general, we have found that lamps larger than 2000 watts use tungsten filaments so large that they do not have time to cool and dim before the power cycles back up. Therefore, we recommend using 2K or greater tungsten light fixtures when shooting above 120fps in 60hz countries and 5K or greater when shooting above 100fps in 50hz countries.
Click to expand...

Hello Mitch,

Thanks for your article. I actually didn't understand why it's ok to work on 2kw Thungsten/120fps in 60hz, and it has to be minimum 5kw Thungsten/100pfs in 50hz?

Thanks

Pat
 
Patrick Tresch said:
Hello Mitch,

Thanks for your article. I actually didn't understand why it's ok to work on 2kw Thungsten/120fps in 60hz, and it has to be minimum 5kw Thungsten/100pfs in 50hz?

Thanks


Pat
Click to expand...

Twice as many amps in the US is the simple answer. A 100w dedo @ 12v is roughly the same as a 2k in Europe in flicker terms. Of course if you run the dedo of a car battery then it wont flicker at all!
 
Stephen Williams said:
Twice as many amps in the US is the simple answer. A 100w dedo @ 12v is roughly the same as a 2k in Europe in flicker terms. Of course if you run the dedo of a car battery then it wont flicker at all!
Click to expand...

I don't get it... Isn't the flicker more Hertz related (50 vs 60) than Watts used?

EDIT: ... I JUST GOT IT, SORRY... ;-)

Thanks

Pat
 
What about LED lights? Is there possible using a few 1200 LED panels for light scene? or some High-power LED lamp like 150W (roughly 1000W in comparison to halogen lamps).
 
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