l 
cardanically mounted to the basket ring of a free Balloon. 
Inclinations of the optical axis between 0° and 30° from the 
vertical were possible by means of a sector arc divided into 
5° intervals. A box level and a magnetic needle were exposed 
together with the ground image on every photoplate for better 
orientation, 
The subsequent years saw the development of further plate 
cameras, conceived primarily for taking aimed single photo- 
graphs of particular objects from aeroplanes and airships: 
- 1911 aeroplane camera, focal lengths f=250 mm, 
f=300 mm and 
f2700 mm 
- 1912 aeroplane hand camera (Fig. 2), focal length f = 250 mm, 
relative aperture f/3.5, plate size 90 mm x 120 mm, 
focal-plane shutter, changing magazine for 12 plates 
1914 balloon camera, focal legth f = 1200 mm 
1914 aeroplane cameras with tilt and swing measuring 
facilities, 
Regarding further technical details, Schumann /1/ cites from 
the literature that the aeroplane cameras employed lenses such 
as the 250 mm f/4,5 Tessar and the 500 mm f/4,8 and 700 mm 
f/5 triplets, The focal-plane shutters allowed shutter speeds 
between 1/50 and 1/800 second, Facilities for exposing tilt 
and swing angles on the photoplates were provided, as already 
mentioned, 
The cameras mentioned above served, without exception, for the 
taking of single photographs and thus had only a limited 
usability for the aerophotogrammetric recording of extended 
ground areas, 
in contrast to these, the large camera developed in 1917 
(Fig. 3), which hat a frame size of 240 mm x 300 mm, was 
capable of exposing series of photos onto film, The film 
cassette accommodated 60 m of film, which lasted for about 
200 exposures, The optical data were characterized by the 
500 mm f/5 triplet and the cloth focal-plane shutter, No fixed 
orientation being provided, the camera was not a metric camera 
in the strict sense, 
Remarkably, however, both film advance and shutter operation 
were performed by electric motors, In an upgraded version of 
the camera, the film was held flat against a perforated, 
ground and polished platen by vacuum action, 
Substantial advances were achieved with the RMK C/1, a serial 
metric camera (Fig.4) built in Jena in 1922, Its frame size 
was 130 mm x 180 mm, and the lens was an 180 mm f/6,3 Tessar, 
with a four-blade between-the-lens shutter, A cassette load 
of 60 m film allowed about 420 exposures. Shutter cockingand 
film advance could be operated either manually or by motors 
powered from a propeller-driven generator with multistep 
reduction gear, A speed controller was provided for controlling 
61