Commission II 
Invited paper, Lisbon 196U 
Analogue (Classical) Photogrammetric Instruments 
by W. SCHERMERHORN 
I.T.C. Delft 
1. Introduction. 
It is not surprising that the short list of presented papers dealing with this subjects 
reflects the rather stable position in the design of this kind of restitution instruments. 
The improvements and even the very few entirely new designs are all based on the clas 
sical principles. As far as new designs are announced, such as from SOM and from 
Galileo-Santoni, they apply the well-known principle of mechanical projection with which 
the perspective rays in space between image point on the photograph and corresponding 
points in the model are represented by steel space rods. Only the introduction of the super- 
wide-angle lens has influenced the design in a few instruments with the aim to avoid 
strong inclinations in the connection between space rod and plate-holder (SOM). 
In this paper we will make only a few introductory remarks, leaving time for the 
designers of new instruments to present their own products during the session. We 
distinguish between the instruments according to the usual classification. 
2. Instruments with direct optical projection. 
This congress also gives the impression that, with the Nistri Photomapper as 
European exception, the use of thi° type of instrument and its refinement is mainly 
restricted to United States production. Private enterprise as well as the US Geological 
Survey state that the bulk of the stereoplotting work for topographic mapping is done 
with the ER 55 Ballplex and with Kelsh plotters. Consequently it is not surprising that 
recent years show improvements on almost all components of these plotters. The paper 
presented by Morris M. Thompson and James G. Lewis of the US Geological Survey 
shows the details of these. The tendency of a certain standardization is certainly sti 
mulated by such a large service like the USGS. It is realized in the universal table 
frame which can be used for all projection distances from the super-wide-angle Ballplex 
with 350 mm to the wide angle Kelsh plotter with 760 mm. 
The Ballplex as well as the Kelsh can be provided at present with super-wide-angle 
projectors, following in this line the Multiplex of Jenoptik, which already 10 years ago 
was adapted to the Russian super-wide-angle cameras. This design of Bausch & Lomb 
and of Kelsh is a proof of the increasing importance of the super-wide-angle photogra 
phy, carried out mainly with Wild RC9 camera. 
Wild Heerbrugg has built for the USGS a special super-wide-angle Ballplex which 
takes diapositives with a reduction 1 : 2 as used in the Wild Autograph A9. This, how 
ever, seems to be a special construction for the USGS which will not be available on the 
market. Regarding the improvements of the tracing table we mention the photo-electric 
pick-up of the so-called autolume reflected light from the red and blue stereoscopic 
images, surrounding the floating mark and energizing a blue and red sensitive photo 
cell which regulates the voltage supplied to the projector lights. This gives automatic 
light balance. 
The increasing application of contrast control has resulted in a 153/153 ratio dia 
positive printer of LogEtronic. The Fluor-O-Dodge system which, according to our ex 
perience, did not work satisfactorily in a contact printer, is now applied to 153/55 dia 
positive printer in which instrument the difficulties of the contact printer are avoided.