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Old Nov 26, 2010, 10:57 AM
Canada
Energy's Avatar
Joined May 2009
1,252 Posts
Discussion
Video Prop Strobe Effect

Is there a way to stop, or decrease the strobe effect of a prop in a video camera?

Would a white propeller help get rid of this annoying effect?

Thank you

E
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Old Nov 27, 2010, 01:05 PM
B for Bruce
BMatthews's Avatar
The 'Wack, BC, Canada
Joined Oct 2002
11,211 Posts
White will reflect more light and make it worse. The strobe effect is occuring because the blades are operating at an RPM that is close to being in synch with the frame rate of the camera. The way to make it less noticable is to run at a different RPM. The shift in RPM doesn't need to be much one way or the other. Likely 20 to 50 RPM and the prop would be a blur instead of a stationary or traveling line. But as you use the throttle there will always be some RPM values that are a multiple of the scan rate where you'll get a slow or stationary prop image.

The only GOOD way to eliminate it is to put the camera outside of the prop or get a dedicated video model with a pusher or twin wing mounted props.
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Old Nov 27, 2010, 05:57 PM
Canada
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Hi, but will white props produce a white effect rather than the black effect?
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Old Dec 05, 2010, 06:15 AM
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BG Bengtsson's Avatar
Sweden
Joined Jul 2010
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Hi,
The strobe effect is the exposure time rather then the frame rate. The frame rate is normally 30fps but the exposure thime is 1/2000s in bright light. This toghether with what is called rolling shutter gives this caracteristic black lines from the propeller. On a proffessional video camera there are normally ND filters.ND means Neutral Density= gray filter. If you add a ND filter you will increase the exposure time. ND64 will increase shutter time 64* to 1/30s.
(All this is due to that in cheap video cameras there is no aperture control.)
If you have a more advanced video camera, where you can set shutter speed manually, you can test with different shutter speeds. On the other hand, too long shutter speed is not good for picture sharpness.
If you take a video after sun set, when it is darker you will see the camera filming at longer shutter time. Then it will be less or no strobe effect.
/BG Bengtsson
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Old Dec 05, 2010, 10:12 AM
Canada
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Thank you! Great info. Will a white propeller make a white strobe effect?
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Old Dec 05, 2010, 01:36 PM
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Sweden
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yes!
With long exposure you will have a grey ring for a dark prop and a lighter grey ring for a lighter prop. Totally a black prop. is best, I think!...
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Old Dec 05, 2010, 02:02 PM
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Thank you!
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