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well as the user, undoubtedly an urgent necessity. Therefore various testing
methods have been developed in the course of the last years.
In order to understand clearly a testing result, it is necessary to have an
exact knowledge of the details of the testing programme. The endeavours of
American and European photogrammetrists has been directed, since the last
Congress in Holland, thanks to the initiative and suggestions of Captain
Reading, towards the creation of standardized testing methods in order to
facilitate the judgment of aerial cameras. In the past four years the coopera
tion of the American and European scientists under the management of Dr.
Howlett has resulted in a repeatedly improved proposal for this test. The
proposal is now before us for discussion. We have the possibility to accept it as
such, to refuse it, or eventually to make new changes. I personally am of the
opinion that the proposal represents a good working base and approaches more
or less the goal which we have set four years ago. In order to come out of the
status of discussion, I think that we should accept it without any additional
changes and have it in force until the next Congress meets.
At the same time I would suggest that besides the testing laboratories of
the manufacturers, there should be at least two neutral testing organizations,
one on the American and one on the European continent, where standard tests
can be executed. These testing stations should be equipped with the most reli
able and precise instruments in order to test all kinds of aerial cameras. In
order to ensure the relative evenness of the tests, these central organizations
should have one to two normal objectives of any make which would permit
them to control at all times the operations and the procedures of the testings.
I think that in Europe, for instance, the International Training Centre for
Photogrammetry in Delft, which is under the management of Professor Scher-
merhorn, could take over this task.
The fact that I recommend the acceptance of the proposal which is before
you, rests on the experience which I have had with a similar testing method
applied in the manufacture of the objectives of the firm Henry Wild. In the
physical laboratories of Wild, each objective lens which is manufactured is
being tested, not only on its geometrical properties, but also on the picture
quality such as foreseen in the proposal. The manufacturing tolerances are
being established in accordance with the proposed test. I can state that we are
very satisfied with this method. It guarantees us a very even manufacturing
quality. In the testing, the geometrical properties of the objective lens are not
in the first place of the discussion. It is tolerances in accordance with the pur
pose of the camera. The certainly in obtaining the results is very high, and the
results can be repeated at any time.
When measuring the resolving power, dispersions of about ± 10% cannot
be avoided. But within this scope the resolving power is as a rule very well
defined. Mostly there is only a dispersion of single measuring points, and the
smoothed curves are almost the same in form and height. Also small manu
facturing errors in the serial manufacture can be easily detected and afterwards
corrected or eliminated.
The text of the proposal can undoubtedly give a neutral judgment for an
aerial camera if it is being made by a neutral central organization. Therefore,
I am in favour of it.
I wish to thank Dr. Howlett in the name of the Swiss Society of Photo-