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3.2___Changes_in_Distortion 
In the diagrams attached to the following figures the results are 
indicated for protected installation (installation in pressurized 
cabin) 
and 
unprotected installation (installed exposed to atmosphere) 
with two versions, viz. 
cabin heated 
cabin unheated 
and in each case for flight heights of 20,000 and ^6,000 ft. The 
effects of air pressure and temperature are depicted separately, 
but their combined influence on the distortion characteristics 
is also made apparent. 
super-wide-angle: S-Pleogon A 4/85 (see fig. 1) 
wide-angle: Pleogon A 4/153 (see fig. 2) 
intermediate-angle:  Toparon A 5.6/210 (see fig. 3) 
Calculations for the 
normal-angle: Topar A 5.6/305 
revealed that all Changes in distortional characteristics at 
flight heights of 20,000 and 46,000 ft remain within 4 range of 
2 um. It was therefore decided to dispense with a graphic 
representation in this case. 
For protected installation coverglasses with the following 
dimensions are introduced: 
  
  
Diameter Thickness 
S-Pleogon A 4/85 720 mm 45 mm 
Pleogon A 4/153 420 mm 30 mm 
Toparon A 5,6/210 420 mm 30 mm 
Topar A 5,6/305 256 mm : 20 mm 
  
- table 5 
Dimensions of Coverglasses -