Blendenwert m
opt.	f-number
phys.	stop value
Blendenwert adj.
opt.	stop number (a measure of the light-gathering power of the aperture; the ratio of the focal length to the diameter of the largest entering parallel beam that can pass through the lens); stop value (a measure of the light-gathering power of the aperture; the ratio of the focal length to the diameter of the largest entering parallel beam that can pass through the lens)