The accuracy of the directions determined with the aid of ballistic cameras is relatively high. This 
is due not only to the extremely careful elaboration of such instruments, but above all to the use of 
a maximum possible number of known fixed stars serving as „surrounding control points“. This 
technique eliminates not only errors of refraction and of the camera system, but also the influences 
of insufficient flatness and dimensional stability of the emulsion or its base. By the introduction of 
close-meshed grids into the image plane of the fiducial marks, these properties may even be improved. 
The aforementioned Topar lenses of 210 mm, 300 mm and 460 mm focal length lend themselves 
to direct conversion to a so-called reseau-type lens, since each of these systems is normally provided 
with a plane plate in the image space required for optical correction. 
1 1 1 1 1 1 ► 
0 20 40 60 90 WO 120 5 [mm] 
Fig. 3 Visual distortion. 460 mm Topar f/4.5, negative 
area 7%” X 7%”, filter D. ISP standard illumina 
tion. Tested on: goniometer. Sign convention: 
DIN 18716. Mean value of several lenses. 
Fig. 4 BMK Ballistic Camera with equatorial mount, in 
conjunction with Zeiss Coudé Refractor. 
Precision Comparator 
The determination of image coordinates from the photographs taken with ballistic cameras de 
mands a coordinate measuring system of high accuracy. For the computations following these 
measurements it is desirable to connect a data output system with the measuring instrument for 
producing the punched paper tapes or punched cards needed for data processing in the correspond 
ing digital computer. Since a large number of known points is usually included in the measure 
ment, it appears logical to precalculate the respective fixed stars approximately from the photo 
graphic data and to introduce these values automatically into the measuring instrument via a setting 
mechanism. Finally, there may be a necessity of making a direct comparison between certain images 
taken at instant A with those taken at instant B, i. e. to view two images simultaneously. 
BuL 2/1964 
63