(110)
some countries. If any further information on certain details is required,
please enquire of the Secretary, Commission I.
This preamble and the boxed “notes” are not a part of the specification
proper.
Specification of Methods
of Calibrating Photogrammetric Cameras and
Measuring their Resolution, Image Illumination and Veiling Glare.
1. Resolving Power.
1.1 Resolving power shall be determined photographically under
conditions approaching closely those which the camera will encounter
in service.
1.2 The camera tests described below may also be used as tests of a
lens alone by mounting the lens on a test bench which is in effect an
adjustable camera. Major changes of procedure to be made in this case
are indicated.
note: For characterization tests of lens types it is necessary to
make photographic resolving power tests in a series of planes
representing a range of focus settings. Convenient laboratory
methods for obtaining the necessary number of exposures and
the necessary focus adjustments usually involve mounting the
lens on a test bench or test camera. Inclusion of this convenient
practice seems entirely desirable.
1.3 Target.
1.3.1 It is not possible at present to standardize on a single type of
resolving power target. One or more of the following four types shall
be used.
1.3.2 Three Line Low Contrast.
This test object consists of three bright lines on a dark back
ground. Line separations are equal to line widths and line lengths are
five times line widths. The difference of log luminance between the
lines and the background is 0.20 ± 0.02.
1.3.3 Three Line High Contrast.
This test object is the same as the three line low contrast test
object except that the difference of log luminance is 2.0 or greater.
1.3.4 Cobh.
This test object consists of two bright lines on a dark background.
The line separation is equal to the line width. Line length is three
times line width. The difference of log luminance is 0.20 ± 0.02.
1.3.5 Annulus.
This test object consists of a bright annulus on a dark back
ground. The outer diameter is three times the inner diameter. The
