SYMPOSIUM PHOTO INTERPRETATION, DELFT 1962 
SPEC IFIC ATIONS FOR MI RROR -ST E R KOSCOP ES 
Classification 
of 
Properties 
The Measurements 
Methods & Means 
Definitions 
Symbols & Units 
Tolerances 
Accuracies 
Properties 
I-Formation 
I-Recording 
I-Quality 
Operational 
Mechanical 
Economic 
Facts 
about 
Graphs 
Measurements 
Hurault 
Jacobs 
Naumann 
König & 
Köhler 
Simon 
and others 
Drawings 
Graphs 
Use the Spec's 
intelligently 
Use of a stereoscope 
in different fields 
Aspects of Different 
Stereoscopes used 
for the same task 
Performance 
Stereoscope No. 
General 
Conclusions 
Specifications 
Good 
Tolerable 
Poor 
j authorized by Manufacturer 
Fig. 1 
Properties 
A useful classification into groups of the various properties is: 
Image Formation: Tracing back the rays of light from the retina to the object, 
the principles and properties involved in the forming of the image will be 
found. This is done firstly for monocular vision, after which stereoscopic vision 
is discussed and finally “scanning”. 
Image Recording: The actual recording by the brain is not discussed, but 
the eye needs a certain energy to function properly, so all influences on the 
brightness of the retinal image will be considered. 
Image Quality: The influence of the stereoscope on the contrast of small 
detail in the transfer from print to eye will be expressed in a Modulation 
Transfer Function (M.T.F. or T.F.). 
Operational aspects: The operator should not feel that he is looking through 
an instrument. A knob or adjustment possibility should have one function 
only and not influence other settings. 
Mechanical aspects: Requirements as to stability, transportability, protec 
tion of mechanical and optical parts against rough handling are discussed. 
Economic aspects: We mention price, time of delivery, service, etc. 
On the complete specification sheets (pp. 48 and 49) each group contains 
5 to 9 subdivisions. 
The simplest methods are used to measure almost every property just 
accurately enough. After all, this is not a production control, where tolerances 
have to be adhered to closely, but a search for significant statistics for stereo 
scopes. We established the procedure and routine on the stereoscopes in use 
at the I.T.C.; in future we will test new instruments along the same lines.