Vertical air photo: A21810-1
Flight height: 25,100 feet a.s.l.; lens focal length: 88.214 mm.
Scale: 1:83,400 (approx.)
Date: August 4, 1970
Location: Townships 34 and 35, Ranges 28 and 29 WI
Map sheets: 1:250,000 62N
The stepped border between
The aim of the air photographer is to take photos under cloudless conditions which makes this photo unusual in that clouds 3, almost white, and their shadows 4, almost black, thrown to the north, are visible. The photo also shows the checkerboard pattern of the sections of the DLS system especially in the southeast 5. This, the first photo in a job, contains all the details of the photography in the bottom left hand corner 6.
Photo A21810-1 was the first photo of line 23 that was flown from west to east and includes photos 1-16. This line was flown on August 4, 1970. Line 21, including photos 17-40 was also flown from west to east but on August 5, 1970. Line 22, which includes photos 41-50, was flown from east to west also on August 5, 1970. Finally line 23, which includes photos 51-59, was also flown from east to west on August 5, 1970. The flight height in all cases was 25,100 feet above sea level and the camera used had a 88.214 mm focal length lens.