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werden. Die Umformung der Verzeichnungseigenschaften geschieht in der be 
kannten Weise mittels auswechselbarer asphärischer Glasplatten. 
Als photographisches Objektiv wird ein hoch korrigiertes Sonderobjektiv ver 
wendet, dessen Brennweite bei der Standard-Ausführung f = 20 cm beträgt. 
Für die Beleuchtung der Originalbilder ist ein System von Böhrenlampen mit 
geringer Wärmeabgabe vorgesehen. Die Belichtung erfolgt automatisch durch 
eine Schaltuhr. Der Operateur sitzt vor dem Gerät und hat alle Bedienungsele 
mente in bequemer Reichweite vor sich, so dass ein langer Dauerbetrieb ohne 
Ermüdung möglich ist. 
A new instrument for the photographic transformation of photogrammetric 
pictures: the Reduetor 
The demand for practically distortion-free lenses, i. e. lenses with linear distortion errors smaller 
than about 3 Li over the complete picture plane can not yet be reached with all types of lenses 
to date. A large number of pictures taken with older optics which show larger distortions are 
not yet plotted. The various stereoscopic plotting machines are equipped, e. g. by means of 
aspheric compensation plates to exactly defined distortion features. With simpler instruments 
mostly freedom from distortion has to be assumed. Therefore, the desire was pronounced to 
transform certain determined photogrammetric pictures to a fixed distortion feature, e. g. to the 
distortion 0, possibly changing at the same time the scale. Since photogrammetric pictures are 
concerned, the transformation has to be made with very much accuracy. The resolving power 
of the original pictures taken at high expenses must not be deteriorated. A special apparatus 
suitable for these tasks has usually to be equipped for a rational processing of a large number 
of images. 
The new »Reduetor» of Zeiss-Aerotopograph answers all these conditions. The instrument allows 
the transformation of photogrammetric pictures up to a picture size of 9 X 9", taken on plates, 
single films and film strips. The transformation can be made either on plates or on metalized 
paper. The magnification range of the standard type amounts to 0.65 <C v <C 1.3. When using 
special lenses reductions up to the ratio 1:0.15 and magnifications up to the ratio of 1:2.1 can 
be executed. The transformation of the distortion properties is being made in the usual way by 
means of exchangeable aspheric glass plates. 
A highly corrected special lense is used, the focus of which is 20 cm in the standard type. 
For the illumination of the negatives a system of tubular lamps with small heat emission has been 
provided. The exposure is done automatically by using an automatic switch. The operator is 
sitting in front of the apparatus and all operational elements can easily be reached so that a 
continuous working will be possible without fatigue. 
E. Santoni: Mechanical 
projection plotting 
instruments modified to 
suit the use of wide-angle 
convergent photographs. 
(Publ. XSl) 
La parole est donnée à M. E. Santoni, Italie, »Mechanical projection plotting 
instruments modified to suit the use of wide-angle convergent photographs». 
Résumé: 
The use of moderately convergent photographs (20°—30°) by standard-angle 
cameras is not recent. Recently, however, some American technicians have been 
using wide-angle pictures with strong convergency (40°), such as to supply the 
ratio B/Z=1.23. 
It is obvious that the best suitable instruments for the plotting of photo 
graphs taken in the above-mentioned conditions, are those utilizing a direct 
optical projection, type Multiplex. With these instruments in fact, it is only 
necessary to tilt the axis of the projecting objective by some degrees with 
respect to the axis of perspective in order to provide the Scheimpflug conditions, 
and graduate opportunely the illumination. 
The use of first order plotting instruments, either utilizing a totally optical, 
optical-mechanical, or wholly mechanical projection, to exploit in a fuller 
way the advantages offered by such photographs, brings forth some problems, 
of greater or lesser importance, concerning the correct stereoscopic vision. 
In particular, some auxiliary optical devices of a special kind (pancratic) 
have to be added in order to equalize in the eye-piece field the apparent 
magnification of the two partial images, at least in the vertical direction (Y). 
Furthermore some mechanical devices for the operation of the Amici prisms 
(Dove) have to be included in order to keep the partial images mentioned 
above oriented according to the points of intersection of the epipolar planes.