Enter the lends focal length and the aperture circle diameter into the calculator to determine the f-stop. This calculator can also determine the focal length or aperture diameter given the other variables are known.
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F-Stop Formula
The following formula is used to calculate and F-stop.
Fstop = FL / AD
- Where F-stop is the correct camera setting for an f-number
- FL is the focal length
- AD is the aperture diameter
To calculate an f-stop, divide the focal length by the aperture diameter.
F-Stop Definition
What is an f-stop? An f-stop is a ratio of the focal length of a lends to its aperture area. F-stop, also commonly referred to as f-number, is usually displayed on a camera when you change the size of the lens.
Example Problem
How to calculate F-stop?
- First, determine the focal length.
For this example, the focal length of the camera is 10mm.
- Next, determine the aperture diameter.
For this problem, the aperture diameter is found to be 5mm.
- Finally, calculate the f-stop.
Using the formula above, the f-stop can be calculated. F = FL/AD = 10/5 = 2.
About F-Stop
What does f-stop affect? Different f-stops will affect the focus, sharpness, and the quality of the image all around.
Is f-stop the same as shutter speed? An f-stop and shutter speed are not the same. F-stop refers to the ratio of the focal length to aperture diameter while a shutter speed is a simple measure of how long a shutter is open for a picture.
