The simpler half-lens was of adequate quality for the narrow angle of view and small relative aperture.
2.
Combinations of shutter speed and relative aperture that resulted in the same exposure were said to have the same " exposure value"
3.
Zoom lenses typically have a maximum relative aperture ( minimum f-number ) of 2.8 to 6.3 through their range.
4.
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.
5.
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 ).
6.
A more typical consumer zoom will have a variable maximum relative aperture since it is harder and more expensive to keep the maximum relative aperture proportional to the focal length at long focal lengths; 3.5 to 5.6 is an example of a common variable aperture range in a consumer zoom lens.
7.
A more typical consumer zoom will have a variable maximum relative aperture since it is harder and more expensive to keep the maximum relative aperture proportional to the focal length at long focal lengths; 3.5 to 5.6 is an example of a common variable aperture range in a consumer zoom lens.
8.
Its film was Ilford Photo SR101 in the form of 0.93in discs punched from 35 mm strip; weight 801; diameter 1.5in; length 1.25in; field of view 186 deg; exposure time 0.3 millisec; effective relative aperture, approximately f / 8; 192 cameras were made in the initial production run.
9.
The f-number ( relative aperture ) determines the depth of field, and the shutter speed ( exposure time ) determines the amount of motion blur, as illustrated by the two images at the right ( and at long exposure times, as a second-order effect, the light-sensitive medium may exhibit reciprocity failure, which is a change of light sensitivity dependent on the irradiance at the film ).
10.
The 1961 ASA standard PH2.12-1961 " American Standard General-Purpose Photographic Exposure Meters ( Photoelectric Type ) " specifies that " The symbol for relative apertures shall be f / or f : followed by the effective f-number . " Note that they show the hooked italic f not only in the symbol, but also in the term " f-number ", which today is more commonly set in an ordinary non-italic face.
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