Measuring the Speed of Moving Objects with Stroboscopic Phot

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Measuring the Speed of Moving Objects with Stroboscopic Phot

Postby kyla_nikole1020 » Sat Feb 02, 2013 8:46 am

I need help with materials. Should I purchase a strobe light or a photography strobe light? Please reply! Thanks :D
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Re: Measuring the Speed of Moving Objects with Stroboscopic

Postby theborg » Mon Feb 04, 2013 5:53 pm

kyla_nikole1020,

Thank you for your question and welcome to science buddies. The answer to your question depends on what and how exactly you are looking to measure. If you are looking to use photography to "catch" multiple images of an object in motion and then try to back out the velocity of the object, then you need to ensure your camera shutter is in sync with the strobe. If they aren't then you will have issues where the shutter could be partially or fully closed when the strobe flash is activated and open when the strobe is not, causing your images to be dark. For this purpose, you may need something a bit more sophisticated than any old strobe light, which may drive you to a speciallized photography strobe. But if you are looking to "slow or freeze" the motion of something that is moving in a repeating patern with a certain frequency, like a wheel turning or a leaver moving up and down, then a regular (i.e. cheep) strobe could work. Again, trying to take pictures whithout a direct sync with the shutter could be difficult. If you were to use video instead, you may be able to, with lots of trial and error, be able to manually dial in the shutter speed and frame rate to sync with the a strobe light, but I've never tried anything like this and am not sure how possible it is.

bottom line: The above comprises some thoughts and ideas for your consideration. However, photography strobe lights can be quite pricy, so I don't want to steer you toward one of those without properly understanding your project. If you could provide some greater detail of your experiment and associated procedures, then we should be able to provide some better advice specific to your needs.
I hope this helps.

theborg
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"As the circle of light increases, so does the circumference of darkness around it."
~ Albert Einstein
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Re: Measuring the Speed of Moving Objects with Stroboscopic

Postby Craig_Bridge » Fri Feb 08, 2013 3:48 pm

How short an interval are you trying to sample at? If 30 frames per second is sufficient, then a video camera is a better choice than strobes.
If you are trying to sample at higher rates, then you could use a strobe that will flash at your desired sample rate. I don't know of any strobes designed for photography that are capable of recovering in less than 1/60th of a second and many of the ones designed for digital cameras have some pre-flashes at lower intensity for automatic exposure control which render them useless for this kind of an experiment using multiple delayed strobes. The problem with using a long shutter speed and a high speed strobes is that you may not be able to tell which image is associated with which strobe pulse if an object bounces and returns on the same path.
-Craig
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