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List of Figures 
1. Evaluation of Crossing MTF's 
2. Co-ordinate System for Slit Object and its Image 
(Spread Function) 
3. Sinusoidal Target and Definition of Modulation 
4. Representative MTF's 
< * 
5* Resolution Prediction from MTF's and Emulsion 
Threshold* 
6* Spectral Sensitivities of Photo Detectors in Covogon 
Measurements. 
7* Comparison of MTF's of 12" f/4 Covogon lens obtained 
by eight different laboratories, Crfield position. 
8. Comparison of MTF's of 12" f/4 Covogon lens obtained 
by six different laboratories, 13 field position. 
< 4 
Appendix 1. 
Composition of Working Group. 
Chairman: Gerald C. Brock, 
W. Vinten limited 
Western Way, 
Bury St. Edmunds, 
Suffolk. 
formerly with: Itek Corporation, 
Lexington, 
Massachusetts, 
U.S.A. 
Members: Clarice L. Norton, 
Fairchild Space and Defence Systems, 
Syosset, Long Island, 
New York, U.S.A.