Synopsis 
The paper presents principles for the establishment of tolerances for photo- 
grammetric instruments and methods and practical applications. The tolerances 
are founded upon calibration measurements, adjustments according to the method 
of least squares, the laws of error propagation, and the confidence limit theory 
from statistics. 
Introduction 
From the Resolutions of Commission II of the International Society for 
Photogrammetry at the Congress in London 1960 is quoted: 
5. “It is desired that principles for the establishment of tolerances and 
specifications for instruments and methods in photogrammetry should be 
worked out” . . . 
The basic instruments in photogrammetry treated in this paper are the com 
parators for the measurements of image coordinates and the stereoscopic 
projection instruments. 
The principles upon which tolerances and specifications are established for 
these instruments may also be applied, sometimes with minor modification, 
to other instruments in photogrammetry such as cameras and similar devices 
for recording the basic central projections of objects to be measured, rectify 
ing instruments, coordinatographs, micrometers, etc. The general principles to 
be applied are indicated in the I.S.P.-Resolution No. 6 of Commission II, 
London 1960: 
“In order to compare the results of different theoretical and practical investiga 
tions into instruments and methods, it is suggested that the observations 
be adjusted by least squares.” 
This basic principle is used for the derivations explained below. The tolerances 
are to be founded upon the concept standard error of unit weight and specific 
elementary statistical principles. In order to be concise in this paper, references 
to existing literature will appear frequently. 
The procedures derived are intended primarily for working photogramme- 
trists to judge the geometrical quality of their instruments.