53 A preliminary investigation into the resolving limit of aeria] | Experience S 
3 : photographs per millimeter 
Pc . recent years, f 
Y Ë 531 Introduction mission is impo 
function for ac 
In Sweden the first investigations into the resolving limit of aerial photograph type of test ta 
E were made by the Air Force and the Royal Institute of Technology. The result Standards (7): 
M. | ; of the photography done by the Air Force from 1949 to 1950 have not been pul Though metl 
lished, but the investigation by the Institute of Technology comprising about ty graphs were pr 
photographs from 1949 has been accounted for by Fagerholm (4). For loy.y, limit for photo 
trast targets of the Canadian type photographed from 400 m altitude, a re, | — 0? the Office. 1 
limit of 6 1/mm was obtained for an old type wide-angle camera, focal lagi before a deter 
b. | 20 em and size 30 x 30 cm. - wise the test t 
In 1952 RAK began certain investigations into the resolving limit of aei. | 
photograph negatives. It was primarily intended to compare old type camen : 
20/30 x 30 cm with modern cameras, type 21/18 x 18 cm for film and 17/14 y i 533 Planni 
cm for plates for the production of mosaic maps on the scale of 1 : 10,000. Ph; 
graphing was continued during 1953 and a new film camera, type 11/18 x 18m 
| was also examined. 
E | Most of the targets used in the tests were annular ones of Howlett typ (j relatively large 
P. | with the logarithmic contrast 0.2, but high-contrast line targets of Foucault ty therefore took : 
, were also tested. The flying altitudes varied from 480 to 3,500 m and a total i Among other i 
160 photographs were taken on test targets. Evaluation was done by means | or indirect bea 
a monocular magnifying glass with enlargement 8 x. The results reported i remission and 
The aerial : 
  
In aerial. ph: 
to achieve repi 
x | 1954 by Welander (6), are shown in the table below: d 
= | Low-contrast  High-contrast lines High-contrast lin 380 x40. Di 
b Camera annular flying direction || flying direction | 30°, Kodaks Ir 
= 20/30 x 30 cm film .........-. 7 1/mm 17 1/mm 11 Jum | film, 
B 2148 x 18 cm film... 12 * ay * 18” The films we 
11/18 x 18 Cm fim ........... M " 03 7 — ground round 
17/14 x 14 em plates ......... 14 C d 19 7 since in actual 
provision must 
Early in the spring 1954 some ten photographs were taken with the then qui: | at that time R 
new camera 15/23 x 23 cm, which gave the value 12 l/mm on the annular bv | tigations were 
Lo contrast targets. type of develo 
x | DK 76, DK 2 
EF and Nogranol. 
E. 532  Resolving limit and quality of the photograph Even if a de 
ment is rather | 
The practical consequence of the investigation mentioned above for RAKws arrangement in 
that photographing for the photo map that previously had been done fi | ferent lengths 
3,900 m with a camera 20/30 x 30, was done by way of trial from 5,000) Weather. In ac 
à | | with a camera 15/23 x 23 over an area of 6,000 square kilometres. The qui} Ilumination as 
^ E of the photographs of the finished mosaic maps came on the whole up to exper development tin 
tion while the gain in time in stereo-plotting and production was essential. Photographic q 
42