USAF TYPE T-ll MAPPING CAMERA*
Leonard W. Crouch, Engineer, Photo Reconnaissance Laboratory,
Wright-Patterson Air Force Base, Ohio
HE Air Force Type T-ll Mapping Camera was designed to fulfill require-
X ments within the military services for a mapping camera to supply pre
cision photography for the photogrammetrist. Besides need to meet the pre
cision requirements, this camera had to be rugged, simple, and easy to operate
and maintain from the military standpoint. The general characteristics of the
camera are as follows: It utilizes the 6"//6.3 metrogon lens; it has a shutter
speed range from 1/10 to 1/500 of a second; it has data recordings; a shutter
synchronizer pulse to actuate external recording devices; and a film capacity of
390 feet of 9| inch wide film.
Designing these characteristics into a mapping camera in such a way that
the precision, ruggedness and simplicity requirements are met, presents a very
formidable engineering problem. There are always very obvious and complicated
paths to follow in order to have a given design meet a set of precision mapping
requirements, and it is only through much thought and redesign that ruggedness
and simplicity of equipment are finally forthcoming. To achieve this end in the
Type T-ll Camera it was decided to adopt and blend together certain basic
features. First of these was to have the precision relationship between the optical
elements and focal plane contained in an inner cone and the magazine platen;
this was to make possible a camera possessing utmost precision and yet being
simple to manufacture, operate, and maintain. The second feature was to use the
Rapidyne drawer type shutter; this would permit the utilization of a high speed,
efficient intralens shutter that could be removed from the lens cone without
disturbing the optical elements. The third and very important feature was to
strive for use of readily removable compact sub-assemblies throughout the entire
camera; this would greatly simplify the camera maintenance problems, thereby
increasing the reliability of the camera. When the final camera design incorpo
rating these features was completed, the result was a mapping camera having
the precision required by the photogrammetrist, the simplicity desired by the
photographer and camera maintenance man and, above all, the ruggedness de
manded by its use in military operations.
The camera magazine does not have forward motion compensation. This is
made possible by the present day image velocities at mapping altitudes. Should
these velocities become great enough to reduce appreciably the quality of the
photography, the forward motion compensation feature will be designed into the
camera system. The camera magazine as we know it today, contains a divided
film compartment, a vacuum sensing and recording device, a removable case
drive and the platen, or vacuum back. The divided film compartment was pro
vided to facilitate loading of film into the magazine while in the dark room; this
requires only the supply chamber to be loaded in the dark and the remainder of
the loading procedure can be accomplished in the daylight. The magazine platen
has been carefully designed to provide a film positioning surface that is flat to a
tolerance of ±5/10,000 of an inch. Special reinforcing of this unit assures the
photogrammetrist that the film positioning surface will retain its flatness
throughout the life of the camera. Located at the vacuum input of the platen is
the pressure sensing device which provides the signal for the vacuum recording.
This feature in the camera is of considerable importance. It registers an image
* Prepared for Seventh International Congress. Permission for publication granted by Inter
national Society of Photogrammetry.
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