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Old Jan 29, 2005, 6:34 PM   #1
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Hello,

I have a nice pair of Swarovski binoculars that have a 10x magnification.

I'd like to know if there is a way to convert focal length of a non-zoom lens into magification that way I have some idea how my lens compares to a 10x magification binocular.

For example, if I purchase a Sigma 300M, which would be 450M if attached to a Nikon D70, would the magnification be equivalent to a 5x, 6x, 7x..etc?

Scott
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Old Jan 30, 2005, 3:22 PM   #2
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The old rule of thumb is 50mm = 1x. So a 300mm = 6x.

Simple?
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Old Jan 31, 2005, 9:06 AM   #3
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So a 300mm camera on a Nikon D70 would be 450mm which would be a 9x magnification, and if I add a 1.4x teleconverter, it would be a 12.9x magnification?
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Old Jan 31, 2005, 11:58 AM   #4
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That is correct. But try not to include the CROP FACTOR in with the magnification. Your lens is not being magnified. You are just capturing the image on a smaller frame...hence CROP FACTOR.

I hope this helps.
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Old Feb 1, 2005, 5:56 AM   #5
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A 50mm lens on a 35mm camera gives approximately the same view as the human eye. This is why the 50mm lens is considered standard on a 35mm camera and is the base when considering the maginification of telephoto lenses,so 100mm lens is 2x 200mm is 4x. With the Nikon digital cameras the sensor is smaller than 35mm film so the image is cropped. This means it takes roughly a 34mm lens on a D70 or D100 to give a 'normal' view equivalent to a 50mm lens on a 35mm camera.

What this means is that on a digital camera a 100mm lens still gives a 2x magnification compared to a 50mm lens. However is gives 3x magnification compared to what you would see with your eyes and gives the same view that a 150mm lens would give on a 35mm camera.

We keep refering back to the 35mm format because this has been around for years and is largely understood by most photographers. In doing so though we do createsome confusion not least in the terminology used to describe the crop factor of the smaller sensor. It's not helped by the fact that different cameras have different sized sensors with different crop factors.

I hope this helps makes this confusing subject a little clearer.



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