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Helicopter Blade / Frame Rate synch? Camera?

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Frank Napolski
Helicopter Blade / Frame Rate synch? Camera?
on Dec 8, 2011 at 4:01:05 am

Hi All,

Any suggestions how I could recreate a shot of a helicopter hovering with its blades virtually unmoving?












How would you calculate the necessary frame rate? Take into account number of blades and RPM?
I'm using an HPX-170--would any other cameras be better suited for variable frame rate shooting?

Thanks for any help

-Frank


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Todd Terry
Re: Helicopter Blade / Frame Rate synch? Camera?
on Dec 8, 2011 at 4:20:46 am

Shouldn't be too difficult at all.

I think trying to calculate it by any kind of math would be fairly fruitless... especially considering the rotor RPM will not be predictable, or at all constant. That's especially evident in the first video, where the rotors appear to move forward a bit, and then backwards. That's because the rotors aren't spinning at a perfectly constant rate, but are being varied by either the drag, the throttle variations of the pilot or both.

Firstly, as you probably know you'll need to shoot at a much higher shutter speed than usual, or the blades will just appear a blur.

Secondly, you'll need a camera that has a "clearscan" mode. I'm not a HPX-170 user, so I can't say if it will clearscan or not (I usually shoot with the Canon XLH1, which does). For cameras that will, the clearscan mode allows you do dial in a very precise shutter speed (usually to stop phasing or flickering from HMI or fluorescent lights, or computer screens). In this case though it would be just as easy to use that to "freeze" the rotors. You'd just start with a fairly high shutter speed, and slowly dial the speed up or down until the rotors appear to freeze. You'll be able to instantly see that in the viewfinder, and shouldn't take more than a few seconds to land on the right speed.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Mark Suszko
Re: Helicopter Blade / Frame Rate synch? Camera?
on Dec 8, 2011 at 3:37:11 pm

Add rolling shutter and props look even MORE trippy and Dali-esque


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Todd Terry
Re: Helicopter Blade / Frame Rate synch? Camera?
on Dec 8, 2011 at 4:03:15 pm

Maybe, not totally sure about that. The blades are moving so fast and the frame rate will have to be soooo high to freeze them that I'm betting a rolling shutter wouldn't come into play much. Still, I always prefer to shoot with global-shutter cameras anyway, hardly ever with rolling-shutter cameras.

T2

__________________________________
Todd Terry
Creative Director
Fantastic Plastic Entertainment, Inc.
fantasticplastic.com



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Mark Suszko
Re: Helicopter Blade / Frame Rate synch? Camera?
on Dec 8, 2011 at 5:07:01 pm







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