(211) 
Dr. Howlett: Thank you very much, Dr. Gardner. On two of your sug 
gestions I believe we can safely comment immediately. In connection with your 
remarks on the effect of veiling glare on resolving power, we should certainly 
add a reference to a paper by Mr. K. M. Baird which presented a quantitative 
measurement of this effect. With regard to your remarks on the desirability of 
permitting photo-electric methods for the measurement of veiling glare and 
image illumination we believe that you will find such methods are made per 
missible by the word “equivalent” which is in Section 3.1 and also in Section 
4.1. We shall arrange to give further consideration to the remainder of your 
comments. 
Dr. F. E. Washer: It is suggested that in Section 2.14, Presentation of 
Results, there be added a statement of the magnitude of lens décentration in 
terms of the effective prism arising from said décentration. If this is expressed 
in terms of prism angle the magnitude of the asymmetric radial distortion and 
the probable magnitude of the tangential distortion can be computed. 
Dr. Howlett: The simplification obtained by representing the effects of 
décentration as being equivalent to those caused by including a prism with a 
perfect lens is very convenient and appealing. However, it has been shown both 
theoretically and experimentally that the prism is too simple and does not 
fully account for the facts. Consequently, there will be many people who would 
object to including a requirement for a statement of “prism angle” in the speci 
fication. However, there is nothing in the specification which precludes the 
addition of a statement of prism angle, or any other specially computed value 
to a report which is based on this specification. 
Is there any further discussion of this specification? If there is not, I sug 
gest that in the course of the next few days, by consultation among the national 
reporters and other interested parties, we prepare a resolution for the Plenary 
Sessions recommending adoption of this specification as a tentative standard 
subject to frequent review. 
The meeting agreed with this suggestion. 
Second Session, Saturday, 6 September, 1952, 11.45 to 12.30. 
Papers given were as follows: 
J. Cruset, France, Practical Tests of Silver Halide Papers for Aerial Photo 
graphy. 
F. E. Washer, U.S.A., The National Bureau of Standards Test Chart. 
I. C. Gardner, U.S.A., The Experimental Evaluation of Lens Performance. 
W. Brucklacher, Germany, A Contribution to the Navigation of Photoflights 
Covering Large Areas. 
Papers read by title were as follows: 
W. Jaschek, Austria, Astrophotographie lens testing. 
Robert Richter, Germany, Topar lens 1:4, focal length 210 mm, for 18 X 18 
cm aerial camera.