Historical information
Aerial photos were used to make maps of forest types, timber resources, to survey logging areas and regeneration, to mark boundaries of public land and new plantations, to identify new roads and tracks, as well as for fire suppression. Infrared film was sometimes used to monitor insect and disease attack.
The images needed to sharp, with high contrast, and in a large format (most were printed in B&W on 9-inch by 9-inch glossy photographic paper) with at least a 60% overlap to enable stereoscopic viewing and with a 20-30% side lap to allow for aircraft drift. Preferably, the photo scale was close to the final map scale avoid to problems when enlarging and to reduce distortion.
Something was needed to supplement the very expensive and infrequent large-area photography programs. From the mid-1960s Victorian foresters began experimenting with small format 70mm and 35mm cameras which proved simple, practical, cheap and flexible.
It was found that any SLR camera could be used provided it had a good quality lens and fast shutter speed (preferably down to 1/1000 second). Motorised cameras with a large film capacity had obvious advantages and were essential when access to the camera was not possible during flight. It is also essential for the shutter to operate at low temperatures and those lubricated with silicones were recommended.
Components of a typical FCV Divisional Office system included –
A Hasselblad or Vinten 70 mm format aerial camera with a focal plane shutter which could be electrically operated.
Interchangeable lenses to allow for different photo scales and flying heights.
Several large film magazines, which were loaded in a darkroom, each with a capacity of 100 feet or approximately 500 frames.
A remote control for the camera in single-shot mode or automatic firing at selected intervals of 2 to 50 seconds. It also needed a frame counter.
A light aircraft was modified with an internal mounting for the camera to keep it level and steady. Often a hole was cut through the floor for the lens.
The aircraft also needed an inbuilt 12 Volt DC battery to operate the motorised camera shutter. The front passenger seat was generally removed to improve access to the camera.
An Aldis drift sight was also fitted. This might be likened to an inverted periscope and is used to determine drift, to facilitate accurate navigation along flight lines and to determine the exposure interval for stereoscopic overlap.
This item is kept at Traralgon.
Physical description
Hasselblad 500 ELM camera with 70mm lens, film pack, motor drive and battery
In 1964 Hasselblad started production of a motorized camera, the 500 EL
The EL/M is a modified version of the EL, "M" means modified, "EL" electric.
Perhaps the most famous use of the Hasselblad camera was during the Apollo program missions when man first landed on the Moon. Almost all of the still photographs taken during these missions used modified Hasselblad cameras.
