Cameras and Rigs
James S. and Susan W. Aber
The camera is a point-and-shoot Samsung Maxima Zoom (38-105 mm) that is secured in the cradle with a tripod mounting screw. A "landscape" button for infinite focus is located on the camera front. This button is depressed by a mini shock cord, which also serves as a safety strap to hold the camera in the cradle. The wide-angle mode (f = 38 mm) is used most of the time, and standard mode (f = 45-50 mm) is utilized occasionally.
The camera has an advanced intervalometer, which can be set to take photos at intervals from 10 seconds up to 60 minutes. The usual setting is one or two minutes between photographs. This allows time to move the camera by walking to a new location or by adjusting the camera altitude (letting out/taking in line). The camera continues to take photos at the preset interval until it is turned off or runs out of film.
|Subject||Location||Subject||Location||KAP rig and kite ||Emporia, Kansas ||Picavet suspension ||Lake Kahola, Kansas||Camera and cradle ||Lake Kahola, Kansas ||View down the line ||Chadron, Nebraska||Gear packing ||Halstead, Kansas ||KAP rig and large kite ||Emporia, Kansas |
Radio-controlled KAP rigs
A single-camera radio-controlled KAP rig was constructed to the authors' specifications by Brooks Leffler (2/98). The goal was to create a versatile and very light system that incorporates the following state-of-the-art design components.
|Radio-controlled KAP rig in action. Camera is set in the "landscape" position for high-oblique views, and the yellow antenna mast serves for visual indication of camera azimuth. The dihedral stabilizers are not shown in this image. Photo date 3/98, © J.S. Aber.|
|Schematic diagram of radio-controlled KAP rig built by Brooks G. Leffler.||View of ground-based setup for operating the radio-controlled KAP rig. J.S. Aber steadies the kite line, while his assistant, Nang Kham Noam (left), operates the radio controls. The kite reel is secured to the car's trailer hitch. All gear, including soft kites, line/reel, KAP rig and accessories, are stored in the large open box. Photo location at Ft. Leavenworth, KS, 4/98, © J.S. Aber.|
Extensive testing has shown the system to be quite stable in flight. Total weight is only 20 ounces (570 g), so with a big kite it can fly in wind as light as 5-7 mph. It also flies well in stronger wind, up to 20-25 mph. Radio controls are very responsive, although the small batteries have a limited working time before they discharge. The antenna on the KAP rig serves to "point" the camera via observation with binoculars.
The need for advanced camera capabilities led to design and contruction of another radio-controlled KAP rig by Brooks Leffler (2/00). This heavy-duty rig is based on the Canon EOS RebelX, which is a 35-mm, full-featured, SLR camera. This camera was selected because its plastic body makes it quite light. The camera is equiped with a plastic zoom lens (35-80 mm focal length), which is also relatively light. The main frame is titanium with aluminum used for other frame components and the Picavet cross. Standard servos with brass gears are powered by a 250 mA battery pack. This rig has full capability for horizontal pan (0-360°) and vertical tilt (depression angle 15° to 90°).
In addition to the regular zoom lens, we utilize super-wide-angle (19 mm) and fisheye (14 mm) lenses for special effects. Although somewhat heavier, these lenses create broad fields of view that can be quite dramatic--see fisheye lens. Two Stylus Epic cameras are mounted on a boom, 93.5 cm (about 37 inches) apart. The cameras point in the same direction and are triggered by microservos via radio signal. The camera boom attaches directly to a large Picavet suspension made of graphite tubing and ultralight blocks. The camera boom can be attached either parallel or transverse to the kite line orientation, which allows four pan positions for the cameras. Cameras can be tilted from vertical to horizontal position by manual adjustment prior to each flight. Designed for extreme lightness, this rig weighs only 870 grams (31 oz.), including two cameras, batteries and film.
camera rig by B. Leffler (2000).
Stereo KAP Rig
A radio-controlled stereo KAP rig carries two cameras that take simultaneous photographs of the same ground area. The stereo rig was built by Brooks Leffler (12/98), based on his earlier experience in building a rig for John Carlson (Leffler 1998). Previous stereo KAP results of Carl Bigras (1997) were integrated into this stereo rig.
In addition to the regular zoom lens, we utilize super-wide-angle (19 mm) and fisheye (14 mm) lenses for special effects. Although somewhat heavier, these lenses create broad fields of view that can be quite dramatic--see fisheye lens.
Two Stylus Epic cameras are mounted on a boom, 93.5 cm (about 37 inches) apart. The cameras point in the same direction and are triggered by microservos via radio signal. The camera boom attaches directly to a large Picavet suspension made of graphite tubing and ultralight blocks. The camera boom can be attached either parallel or transverse to the kite line orientation, which allows four pan positions for the cameras. Cameras can be tilted from vertical to horizontal position by manual adjustment prior to each flight. Designed for extreme lightness, this rig weighs only 870 grams (31 oz.), including two cameras, batteries and film.
|Closeup view of stereo KAP rig in flight. Note camera boom is parallel to kite line. This position minimizes wind drag and tilting of the rig. Photo date 12/98, © J.S. Aber.|
|Stereo KAP rig suspended from the line below a large rokkaku kite. The small dihedral wings help to stabilize the camera boom parallel to the wind. Photo date 12/98, © J.S. Aber.|
Stereo photos allow the viewer to "see" the scene in three dimensions, when photo pairs are viewed through a special device, called a stereoscope. Stereo photography is the basis for accurate measurements and mapping based on principles of photogrammetry. Thus stereo KAP has great potential for scientific surveys and mapping.
|Vertical, stereopair, kite aerial photographs taken over cemetery, Emporia, Kansas. Click on the small image to see full-sized version (129 kb). Photo date 12/98, © J.S. Aber. See another stereopair. The image below shows a Sokkia mirror stereoscope.|
The dual camera rig is relatively heavy at 1.5 kg (53 oz.). In order to save weight, the radio control operates the camera shutters only. Tilt and pan positions of the cameras are set manually on the ground prior to each flight. Given its weight, this rig requires a moderage wind (>10 mph or 15 km/h) to lift it. A yellow filter is used normally on the color-infrared camera, in order to eliminate blue light from exposing the film.
|Dual-camera rig. The cameras are positioned vertically in this view. Photo date 2/99, © J.S. Aber.|
|Closeup view of dual-camera rig in vertical position. Note the yellow antenna mast and Picavet suspension system. Photo date 2/99, © J.S. Aber.|
Color-infrared film does not have a "speed" rating (ISO number), nor do camera light meters measure the amount of infrared radiation in the scene. On this basis, f-stop and shutter speed must be set manually based on an estimate of available light. For full-sun conditions, we have found that camera settings of 1/250 shutter speed and f-11 to f-8 work best for our camera/lens system, but some trial and error is inherent with this method. Short-wavelength infrared is especially reflective from active vegetation, so the coverage of active tree and grass leaves has a strong influence on how much short-IR is reflected from the ground. The combination of normal-color and color-infrared images is particularly useful for environmental studies of surface water bodies and vegetation cover.
|Low-oblique, normal-color view of forest, lake and small clearing. Boy Scout camp Jayhawk, near Topeka, Kansas. Photo date 6/99, © J.S. Aber.|
|Color-infrared view of forest, lake and small clearing. Boy Scout camp Jayhawk, near Topeka, Kansas. Active vegetation appears as red and pink in this false-color image. Photo date 6/99, © J.S. Aber.|
|More on color-infrared film.|
All text and images © by the authors; last update Jan. 2008.