terms of MTF for ERTS-1 and Skylab-2 systems, in which opera- 
tional MTF as derived by analysis of natural edges was compared 
with design expectations, with satisfying agreement in most cases, 
Corbett28 described his evaluation of the Skylab multi-spectral 
photographic facility using both visual edge-matching and detailed 
edge analysis methods. Johansson and Biedermann29 described 
a new lensless technique for measuring MIF of film, using fine 
interference fringes, which permits extension of such measurements 
to very high spatial frequencies (past 1000 cycles/mm for example.) 
4.5.2 Calculation of OTF from Design Parameters 
H, H. Hopkins30, in his review of the development of 
image evaluation methods which opened the conference, included 
a most thorough and instructive treatment of the theoretical 
basis for MTF. Several Papers dealt with programming strategy 
or other practical aspects, including an interlaboratory comparison 
study by MacDonald31 which found that in the current state 
of the computational art, different design programs may give 
substantially different answers at high field angles, although 
general agreement was excellent near the axis (Hopkins and Dutton 
reported similar results ^), Several papers discussed the use 
of OTF as an aid in design or selection of the imaging component 
in an overall system. 
4.5.3 OTF Standards 
One session featured reports on the progress of various 
national efforts to establish documentary or physical standards 
for OTP, In Germany (reported by P. Kuttner),32 two parts of 
à proposed five part DIN standard have been issued to date, and 
extensive cross-calibration MTF data accumulated on two standard 
lenses, one a nine-element high aperture 100-mm objective (f/3.2) 
to 13? semi-field, and the other an eight element, 90 mm f/5.6 
wide angle objective to 459 semi-field. For the United Kingdom, 
A. C. Marchant33 reviewed the extensive work of several years 
which was the basis for the British OTF Standard adopted in 1971, 
and the subsequent experience with use of the Standard and OTF 
methods in general, for production and testing especially of aerial 
camera objectives. For Japan, K. Murata and T. Ose reported 
the progress of the JOERA comnittee which has developed a series 
of standard lenses, each designed to test a particular class of 
Problems in MTF measuring equipment; and is preparing a documentary 
standard, expected to be issued in 1976, which will deal with 
standard means of measurement, standard ways of graphical repre- 
sentation of MTF results and inspection standards for the measuring 
equipment. For the Netherlands, J.A.J. van Leunen35 stressed the 
practical issues that have to be embraced by an OTF standard with 
particular emphasis on the tendency of real devices to display 
non-ideal behavior. (Several Papers mentioned here have also 
been reprinted together in a topical section of Optical Engineering36.) 
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