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PHOTOGRAMMETRIC ENGINEERING 
U. S. Ars FoncE— WRIGHT FIELD 
Ever since the inception of a photo- 
graphic unit in the Engineering Division 
of the U. S. Air Force, a detachment of 
Corps of Engineer personnel has been as- 
signed to cooperate in the development of 
suitable aerial photographic equipment 
and auxiliary accessories necessary to pro- 
duce accurate tactical maps from aerial 
photographs. The Corps of Engineer De- 
tachment and the Photographic Unit, 
now expanded to the Photo Reconnais- 
sance Laboratory, have worked together 
on this program since 1920 and the follow- 
ing major items, which have contributed 
considerably to the science of photogram- 
metry have been developed by the U. S. 
Air Force. 
Early in 1921 the T-1 (tri-lens) camera 
was developed as an accurate tactical map- 
ping camera from which suitable maps 
could be made. The basic design of this 
camera was originated by James A. Bagley 
of the Corps of Engineers and through 
various stages it grew into a four-lens 
camera (T-2A) and then into a five-lens 
(T-3A) camera. This multiple-lens camera 
culminated eventually into standardization 
of the T-3A cameras as an operational 
item in 1933 and was later used as a tan- 
dem installation with two five-lens cam- 
eras in a single mount, thereby producing 
an octagonal picture. The tandem set-up 
was used extensively until 1939. Asso- 
ciated equipment, such as transforming 
printers and alignment templets, were 
also developed for use with this camera. 
In 1934 a German RMP-10 camera 
with a wide-angle 10 centimeter f/6.3 
Topogon lens was imported. This wide- 
angle lens opened up a new field in the 
development of mapping cameras, and a 
6-inch Metrogon was produced by the 
Bausch and Lomb Optical Company; the 
optical design of the Topogon was used 
as a basis to provide a lens that would 
cover a 9X9-inch format, thereby enabling 
the use of 91 inch film which was Air Force 
standard. 
At a later date (1939-40) a 12-inch 
Metrogon lens was produced and was used 
in 18X 18-inch format. It has since been 
used on the 9X 18-inch format to cover 
large areas at small scale in a minimum of 
flying time. 
As a result of the development of the 
6-inch Metrogon, the T-5 mapping camera 
was produced in 1940 and was used as an 
Air Force mapping camera until the end 
of World War II. After this the T-9 and 
later the T-11 cameras were developed. 
The T-11 camera is now considered as the 
standard tactical mapping camera for the 
U. S. Air Force. A quantity is now being 
procured for tactical mapping outfits. 
To permit the production of more ac- 
curate maps from aerial photographs and 
to eliminate a considerable part of the 
laborious work required, several attempts 
have been made to stabilize the mapping 
camera. As early as 1921 a stabilization 
unit, controlled by a gyro, was geared into a 
a standard camera so that it would achieve 
a measure of stabilization and produce 
more satisfactory photographs. However, 
due to a lack of accurate and powerful 
gyros the stabilization of cameras was 
abandoned in 1925, and was not taken up 
again until 1943. It was not until 1947, how 
ever, that a satisfactory automatic stabi- 
lized mount was developed that could be 
used in conjunction with mapping cameras. 
With the advent of the tactical mapping 
camera it was necessary to provide suitable 
processing, drying, printing, and projec- 
tion equipment so that more accurate re- 
sults could be obtained from exposed nega- 
tives. Work along this line resulted in the 
development of the E-2 (Steinman) proc- 
essor in 1928, the B-5A in 1937, and the 
B-6 in 1942. As requirements became more 
exacting it was necessary to consider the 
shrinkage of film used in aerial cameras. 
After considerable tests, research, and 
cooperation with industry a low-shrinkage 
film base which eliminated considerable 
inaccuracy was developed in 1932. This 
development called for further develop- 
ment of a low-shrink waterproof-base 
printing paper in 1935, and later (in 
1937) a white-pigmented base printing ma- 
terial that was used extensively for the 
assembly of the composite pictures from 
the T-3A camera. All of these various de- 
velopments have permitted greater ac- 
curacy in the production of maps made 
from aerial photographs. 
There was a great need for a suitable 
type of aircraft which would carry aerial 
photographic equipment to the most de- 
sirable altitude at constant level, which 
would have sufficient range, and also be 
reasonably stable during flight. While