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[ ISP Commission II, Invited Paper | 1 
The Development of Analogue Instruments 
H.C. Zorn 
I Introduction 
At nearly all recent congresses several new developments of analogue 
instruments have been reported. The report of 1972 (Makarovié, Recent Instru- 
ment Development in Europe and Asia, invited paper Commission II ISP ) con- 
tains a description of six completely new instruments. This time there are only 
three to report, not counting the two more specialised instruments. 
II New Instruments 
Three new plotters for aerial photographs have been introduced: the 
Topoflex (Carl Zeiss, Jena), the Planitop (Carl Zeiss, Oberkochen), and the 
Stereosimplex G6 of Galileo-Santoni, Florence. The table shows some of the 
main characteristics of these instruments. For comparison with known instru- 
ments, the B8S and the PG2 are listed as well. It should be borne in mind that 
these two instruments are more expensive than the three new instruments, 
which are all about the same price, as far as is known. 
1 The Topoflex, Zeiss Jena 
(ref Szangolies, K. and Bauer, G., Topoflex, ein neuer Doppelprojektor, 
Jenaer Rundschau 20, 4/1975). 
The purpose of the instrument is stated as being: to provide an instru- 
ment entirely suited to map completion and revision, to the planning of roads, 
industrial centres and towns, and to be useful also as a teaching instrument. The 
instrument is a double projector, comparable to the double projector of Zeiss 
Oberkochen, but even more to the Photorestituteur type 920, of SFOM-Matra 
(France). It has in common with the latter the double projection table, the 
images being observed by means of a stereoscope. Thus the problems involved 
in image-separation by means of colour- or polarisation filters are avoided. 
The necessary parallel guidance of the double tracing table with the 
stereoscope is effected by a three-dimensional compound slide. Instead of 
carrying the pencil itself, this slide is connected with another (two-dimensional) 
slide which moves immediately under the first, allowing a magnification of at 
most times two, which carries the pencil. 
UDC No. 528.722.63