relative aperture การใช้

The simpler half-lens was of adequate quality for the narrow angle of view and small relative aperture.
Combinations of shutter speed and relative aperture that resulted in the same exposure were said to have the same " exposure value"
Zoom lenses typically have a maximum relative aperture ( minimum f-number ) of 2.8 to 6.3 through their range.
High-end lenses will have a constant aperture, such as 2.8 or 4, which means that the relative aperture will stay the same throughout the zoom range.
Extremely small apertures such as f / 64 can be used without issues of diffraction on the lenses, of much larger focal length than those used for smaller images ( a small relative aperture is still a fairly large hole, reducing diffraction ).