A lens' ƒ-numbers depend on the focal length of the lens and the diameter of its aperture.
|
HALF STOPS
This comes from our "Department of Knowledge You May Never Use."
If you want to know what the exact halfway point between two ƒ-stops is, add the previous two ƒ-stops together. For example, to find the half-stop between ƒ-4 and ƒ-5.6, add 2 + 2.8, and you will get 4.8. This works for all ƒ-stops. For instance, the half-stop between ƒ-8 and ƒ-11 is 9.6, derived from adding the two previous ƒ-stops (4 + 5.6) together.
ALL THE STOPS THERE ARE
We'll make it even easier for you, and give you the entire scale of full and half-stops from ƒ-1 to ƒ-90. We don't know what you'll do with the information, but here it is: 1, 1.2, 1.4, 1.7, 2, 2.4, 2.8, 3.4, 4, 4.8, 5.6, 6.8, 8, 9.6, 11, 13.6, 16, 19, 22, 27, 32, 38, 45, 54, 64 and 90.
HOW A LENS' ƒ-NUMBERS ARE DETERMINED
A particular lens's ƒ-numbers depend on the focal length of the lens and the diameter of its aperture. The focal length of the lens divided by the lens aperture's diameter is an ƒ-number. For example, a 50mm lens with a 25mm aperture is ƒ-2, whereas a 200mm lens with a 50mm aperture is ƒ-4.
|