I have heard of lenses being described as fast that have f/stop values of f1.2 and f/2.8.
My question is why are such low f/stop lenses called fast?
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Sign up to join this communityI have heard of lenses being described as fast that have f/stop values of f1.2 and f/2.8.
My question is why are such low f/stop lenses called fast?
Directly from the wikipedia, I couldn't have said it better myself.
A lens with a larger maximum aperture (that is, a smaller minimum f-number) is called a "fast lens" because it delivers more light intensity (illuminance) to the focal plane, achieving the same exposure with a faster shutter speed.
To explain the why "low f/stop" part: this is a ratio. Hence the smaller the number, the bigger the amount of light.