COMMISSION I 
PHOTOGRAPHY AND NAVIGATION 
by P. D. CARMAN 
Canadian photography for photogrammetry has improved greatly in average 
quality in the period 1956 to 1959 inclusive. Total area covered has decreased some- 
what from the previous four-year period. 
The total area photographed was 1,500,000 square miles. A major portion of this 
was 1,150,000 square miles of vertical photography of the arctic islands and the northern 
mainland at a scale of about 1:60,000, to be used in making new maps at a scale of 
1:250,000. For air triangulation to control some of this mapping, 4000 line miles were 
covered with vertical photography and air profile recording. In British Columbia 
34,000 square miles were photographed at 1:32,000 for new maps at 1:50,000. For 
revising 1:50,000 maps, 150,000 square miles were covered by vertical photography at 
1:40,000 in south central Canada. Agriculture and forestry were also large users of 
vertical photography, with a total area covered of about 100,000 square miles. A wide 
variety of scales were found useful — from 1:32,000 to 1:8000 in routine use, up to 
1:4000 in forestry photo-interpretation and 1:3000 for block pile inventory. 
The improvement in photographic quality is due largely to the increasing use of 
better cameras. Most photography is now done with the Wild RC5a and RC8 cameras. 
The Zeiss RMK 15/23 has also come into use and most recently the Wild RC? super- 
wide-angle. The 6” Wild and Zeiss cameras have inherently better resolution, better 
image illumination, and less distortion than the older cameras. 
As is to be expected with any new camera, extensive service use and yearly 
recalibration of about 30 Wild 6" cameras have revealed deficiencies and opportunities 
for improvement. Wild of Canada and Wild Heerbrugg have been very cooperative 
in making improvements. A number of these improvements are described below. 
It was found in 1956 that photographic calibration in Canada did not give the same 
distortion curve and calibrated focal length as did visual calibration by Wild*. Since 
then Wild have supplied new cameras to Canada with photographic distortion corres- 
ponding to the curve shown in Wild publications and have readjusted a number of older 
cameras in the same manner. 
Vacuum backs in magazines were found to be changing shape between seasonal 
calibrations. Wild replaced them with a stiffer design which has proved satisfactorily 
stable. 
It was found that the RC5a optical unit could be distorted by stresses applied 
through its four-point connection to the body if anything disturbed the coplanarity 
of the mating surfaces. Wild added a pivoted bridge to the RC5a bodies, effectively 
providing three-point support. 
Filter deviation and change of deviation tests showed filters were introducing 
asymmetries and tangential distortions that were excessive by comparison with the 
quality of the basic optical units. Wild replaced the filter with ones of excellent 
quality. 
Orientation of filters on cameras was not well established originally. Now Wild 
pins filters in their holders to prevent rotation and large painted index marks show the 
proper position of the filter on the camera. 
*P. D. Carman and H. Brown, “Differences between Visual and Photographic Calibrations of Air Survey 
Cameras.” Photogrammetric Engineering, Vol. XXII, No. 4 (September 1956), pp. 623-626. 
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