USAF TYPE T-ll MAPPING CAMERA 
7* 
b 
DIRECTION 
TRANS 
OFFILM 
PORT 
Fig. 1 
opening and closing times are constant and only the time between actuation of 
the “A” and “B” blades varies. This means that the shutter mechanism works 
no harder at 1/500 of a second speed than it does at 1/10 of a second, and there 
is no compromise required in order to obtain the high speeds. The shutter is 
designed in such a way that the gears, levers, springs, etc., required to provide 
the motive force to actuate the blades, are contained in an assembly apart from 
the shutter blades. The blade assembly has been made thin enough to fit be 
tween the optical elements of the lens, and is attached to the drive mechanism 
by means of thin plates and mechanical links. Thus we have the drawer type 
shutter with the drive mechanism attached to the lens cone, and the shutter 
blades inserted between the lens elements through an opening in the side of the 
lens cone. 
Another significant feature contained within the shutter assembly is a syn 
chronized switch. This switch is actuated when the shutter leaves of the “A” 
side reach a fully opened position. The pulse resulting from this unit can be 
utilized to trigger a flash recording system in a remote auxiliary data recorder. 
In actual tests it has been possible to synchronize the remote recorder with the 
1/500 second shutter speed to an accuracy of one millisecond. The speed range 
of the shutter, as stated before, is 1/10 of a second to 1/500 of a second. This