1.7 
1.74 
1.7.2 
1.8 
1.10 
axis angles (at least 6) to permit preparation of reliable curves between field 
angle and resolving power, to the limit of the field. 
Focus Setting 
A complete camera shall be tested as received. For full characterization of 
a camera (or lens) tests shall be made at a number of focus settings sufficient to 
ensure accurate location of the focus setting which gives best average resolution 
(see 1.14). 
When a lens is being tested alone it shall normally be mounted so that the 
machined face which would orient it on a camera is parallel to the emulsion sur- 
face. Any other method of orientation used shall be fully described. 
Filters 
Any filter normally used on the camera shall be in place during the test. If 
more than one filter may be used in service the camera shall be tested with each. 
Any filter which is used shall be fully described in the report. Preferably its 
spectral transmission curve should be given. 
Apertures 
Tests shall be made at full aperture and at any other apertures for which 
data are desired. The apertures used shall be specified in the report. For full 
characterization of a type of camera (or lens) tests shall be made at three or more 
apertures except where the camera mechanism provides fewer than three aper- 
tures. 
Emulsion 
The camera (or lens) shall be tested with the same sensitive material as is 
used in actual practice, or if this is impractical with one which is as closely 
equivalent as possible. If it is necessary that the usual test material differ slightly 
from the service material typical tests shall be made with both materials and all 
reports shall indicate the magnitude of the error introduced by the change in 
sensitive material. The sensitive material or materials involved shall be fully 
specified in the report. The maximum resolving power of the material for the 
type of target, illuminant, and processing used in the test shall be stated. 
  
NOTE: For measuring resolving power of sensitive materials suitable 
resolving power cameras using apochromatic microscope objectives have 
been described by Perrin and Altman, J. Opt. Soc. Am., 41, 265, 1951, and by 
Hariharan, J. Opt. Soc. Am., 46, 315, 1956. An American standard is in 
preparation. 
  
  
  
Exposure 
The same exposure (object luminance and time) shall be used at all field 
angles. It shall be that exposure which gives best average resolving power. 
Development 
Development shall be a well-controlled equivalent of the average found in 
actual practice. The development procedure and the gamma achieved shall be stated 
in the report. 
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