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General HD (720 / 1080) Acquisition
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Old August 5th, 2006, 09:57 PM   #1
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Optical to MM coversion

I read alot of nature sites for locating waterfalls and such, and many say that the falls from a certain view require a 150mm telephoto lense, or 300mm telephoto lense and Im wondering if there is a good or rough way to convert optical to milimeter or visa versa.
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Old August 7th, 2006, 12:00 AM   #2
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Depends on the size of the imager you're using. For 1/3" cameras, the typical conversion factor is 7.2, meaning that you'd multiply your 1/3" video camera's focal length by about 7.2 to get an approximation of what length of lens you'd need to use on a 35mm still camera to achieve a similar field of view.

So -- a 10mm lens on a 1/3" video camera usually approximates to about a 72mm lens on a 35mm still camera.
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Old August 7th, 2006, 11:13 AM   #3
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Do you mean a 10X optical lense? I dont need to go mm to mm Im trying to figure out what my 12X opitcal is equal to millimeters
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Old August 7th, 2006, 01:04 PM   #4
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There's no way to know that just from the "10x" label. Because, it's 10x what? "10x" means that it has a zoom range that means its maximum telephoto is 10x as long as its minimum wide angle setting. But it doesn't tell you what that wide-angle is, so you have no basis for comparison.

You'd have to find out what the minimum focal length is in order to start comparing. For example, the DVX100 is a 10x lens, and its minimum wide angle is 4.5mm, so it's 10x4.5, or a total zoom range of 4.5 to 45mm.
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