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Appendix 5 
Proposed Supplement to ISP Document: “Recommended Procedures 
for Calibrating Photogrammetric Cameras and for Related 
Optical Tests. 
1• The supplement is to be inserted immediately after the 
section on Resolving Power, with appropriate re-numbering of 
paragraphs• 
2. The Preamble is to contain the following, to be inserted 
after the last paragraph of the present text: "In recent years 
considerable attention has been paid to the Optical Transfer 
Function (OTF), and Modulation Transfer Function (MTF) in view 
of their potential advantages sis an objective physical method 
for measuring the imaging performance of lenses. While much 
further experience is necessary this section has been included 
on a provisional basis to ensure that certain conditions and 
precautions, already shown to be necessary, shall be observed 
when measuring OTF's for photogrammetrie lenses. The emphasis 
is placed on testing lenses rather than lenses in cameras, 
because the transfer function is associated with the lens as 
a separate entity. If the measurement technique is suitable, 
lenses in cameras can be measured, but it is not envisaged 
that measurement of the transfer function of cameras would 
become an invariable requirement. In some cases the direct 
measurement of a camera transfer function would not be pract 
icable” • 
3* Title of Section to be: Modulation Transfer Function and 
Optical Transfer Function of Photogrammetrie Lenses. 
4* Text: Insert the following after the Section 1, Resolving 
Power: 
2.1 The OTF and MTF may be measured by any of the several 
known methods but the technique and equipment used shall be 
calibrated or qualified by measuring the MTF or OTF of known 
standard lenses. 
2.2 Illuminant and Spectral Sensitivity 
The illuminant shall be "mean noon sunlight" as defined in 
Section 1*4. The spectral sensitivity of the detector shall be 
such that its response to an equal energy spectrum in conjunct 
ion with any necessary correcting filters, shall be level within 
¿0.2 log sensitivity units between wavelengths of 0.4 and 0.7 
micron. When measurements including the near infrared are to 
be made, the response shall be similarly level over the whole 
of the included wavelength region.