Appendix 
SYMPOSIUM OF COMMISSION I 
September 19th - 23rd 1966 
The symposium was held at University College, London and there were 68 
registered participants. The main field for discussion was photographic 
image quality, particularly the use of optical transfer function methods in 
measuring and defining the performance of lenses, films and cameras. However, 
the opportunity was token to consider the whole programme of the Commission 
and the arrangements for Lausanne. 
1. Session 1 Sept. 19th 
Mr. G-. C, Brock, Jtek Corporation, USA and Chairman of the Working 
Group on Image Quality, described the work done in his laboratories. He 
pointed out the difficulties that had arisen in the application of the 0, T.F. 
concept to complete air photographic systems, in particular the non-linear 
behaviour of the photographic emulsion and the variation with processing 
technique. Of more immediate concern however is the fact that measuring 
techniques for lenses have not yet attained sufficient accuracy for reasonable 
agreement to be found between different laboratories. And yet the great 
attraction of the D,T.F. method, was that it appeared to offer an accurate and 
objective means of characterising lens performance. The main task for the 
W.G, in the time remaining before Lausanne should be the solution of the 
problem of measuring accurately and consistently the 0.T.F. of lenses, and the 
drafting if possible of a Standard on this. 
Dr. D. Kelsall. of Itek Corporation, USA described in detail a 
programme, initiated by Mr. Brock, in which the same lens was measured by 8 
laboratories in various countries. These results differed from each other by 
substantially greater amounts than the error limits estimated by the individual 
laboratories for their own tests. The particular lens chosen might not have 
been ideal for the purpose, but the situation is recognised as a general one 
and investigation is needed. 
Dr. L. R. 3aker, SIRA, U.K, desoribed some of the factors, spectral 
balance of light sources*", stability of equipment, environmental effects, 
surface finish of the lens, etc., which his group had found to be important in 
measuring 0.T.F, He went on to suggest the use of a simple optical component, 
such as a 6 inch f/K plans convex lens as a basis for comparing different 
measuring equipment. He listed the advantages of such a procedure end expressed 
willingness to supply data to those interested. 
Prof, B. Hallert, Sweden, queried the significance of the estimates of 
accuracy quoted by the laboratories in the tests described by Dr, Kelsall. 
Anyone making such statements needed to declare (@) the nature of the estimate 
of errors (r.m.s., probable, maximum, etc.) and (b) the level of confidence 
associated with the values. 
Dr. II. K. Meier, Federal Germany, said that although the absolute 
measurement of 0. T.F. could entail these difficulties, the comparison of a 
number of similar lenses by the some measuring equipment, as for example in the 
production run, was still valid and extremely useful. 
Other contributors to the discussion mentioned other factors, such as light 
source coherence, stray light, etc. which can be of importance in 0.T.F. 
measurement. 
/2, Session