Camera Design 
Now, however, NASA is developing a Large Format Camera (LFC) as a pay- 
load for the cargo bay on the Space Shuttle. The fundamental parameters 
of the camera are: 
focal length = 30.5 cm 
format 23 x 46 cm 
aperture = f/6.0 
u 
The camera will be mounted such that the long dimension of the format 
will be in the direction of flight. 
The lens consists of 9 optical elements plus an antivignetting filter 
as shown in Figure 1. It has a maximum distortion of 15zım over the 
entire format and 10 um over the center 23 x 23 cm portion of the for- 
mat. The lens is color corrected for wavelengths from 0.40 to 0.90 um. 
Optical filters can be inserted in the center of the lens to correct 
the color balance for black-white, natural color, or color infrared film. 
These filters will be mounted in a motor driven turret which can be changed 
by external command. The lens has a resolution of 80 line pairs per milli- 
meter AWAR, with a minimum of 50 line pairs per millimeter in the corner 
of the format. The dynamic ground resolution produced by the lens is 
indicated in Figure 2. At the nominal operating altitude of 300 km, 
(160 n.mi.) the ground resolution is approximately 14 meters on high 
resolution black-white film, aud 25 meters on color infrared film. It 
is worthy of note that this is photographic resolution and not pixel 
dimension as normally given for electro-optical systems such as Landsat. 
The 14 meter photographic resolution is approximately equivalent to a 
6 meter pixel dimension in terms of detail visible in the images. A 
prototype lens has already been built and tested, and the expected values 
for distortion and resolution have been verified. 
The between-the-lens shutter is more or less conventional with rotating 
disks and a capping blade. Relatively slow shutter speeds are required 
to expose high resolution black-white and color films. Exposure times 
covering the range of 0.006 to 0.024 seconds can be established from 
the operator control point or by a scene brightness sensor. This sensor 
has a 5° field of view and integrates the scene brightness for 15 seconds 
prior to shifting the exposure duration. This technique nullifies the 
effects of high brightness levels from clouds, snow patches, sun glint, 
etc. 
The camera magazine, as illustrated in Figure 3, will have a maximum 
capacity of 2,000 meters of film sufficient for 4,000 frames, À film 
spool containing this much film is very heavy, and it is necessary for 
it to rotate continuously during camera operation to avoid the serious 
vibration effects of starting and stopping. Lightweight dancer rollers 
are provided on both the supply and takeup sides to accommodate the film 
which is unspooled during camera cycle time. The film will be held 
against the platen by a negative pressure differential between the lens 
cone and the camera back. In order to provide this pressure differential 
  
  
  
  
  
  
  
   
   
  
  
  
   
  
  
  
   
  
   
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
  
   
  
  
  
  
  
  
  
   
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