KAP camera rigs

Kite Aerial Photography
Cameras and Rigs
James S. and Susan W. Aber

Table of Contents
Introduction Digital KAP Canon Elph
Canon Rebel Canon S70 Tetracam

**Table of Contents**
Introduction	Digital KAP	Canon Elph
Canon Rebel	Canon S70	Tetracam

Introduction

During the past several years, we have employed several types of KAP rigs and cameras. Our original setup is a manual rig with a camera that takes pictures at preset intervals. Our other systems are state-of-the-art radio-controlled rigs built by Brooks Leffler, in some cases with our own modifications. All our rigs employ Picavet suspension systems (cable and pulley), and we use rechargable nickel-metal-hydrate batteries for dependable power in the field.

We began with film cameras in 1996 and added digital cameras starting in 2001. High-resolution digital cameras now rival 35-mm film for image quality, and digital technology has many advantages over film techniques for kite aerial photography. Most important is the ability to review pictures immediately in the field in order to confirm successful photography. The ability to edit, display, and print digital images shortcuts photochemical processing, and digital files do not degrade with time, as color film does. Finally the cost of such digital photography in now competitive with equivalent film methods. For this reason, we now utilize Canon digital cameras for most of our kite aerial photography. The section on film camera rigs is given for historical purposes.

Most of the cameras described below were purchased
from Wolfe's Camera, Topeka, Kansas.

Digital KAP rigs

Canon Digital Elph (2001-2006)

High-resolution digital cameras have become increasingly available at moderate cost. The problem of putting high-resolution and good optics into a small digital camera was solved for us first with the Canon PowerShot S100 Digital Elph (also known as the Digital Ixus in Europe). The camera is the size of a credit card and weighs just over 7 oz (200 g) including the battery. It has a 1600x1200 CCD pixel array and a zoom lens, which together produce amazingly clear pictures. The stainless-steel body is especially attractive for rugged field use. Brooks Leffler constructed an efficient rig to fly the Canon Digital Elph (3/01). The rig features full radio control of camera tilt, pan, and shutter trigger (see below). Weight of the complete rig with camera is just 625 g (22 oz).

Image courtesy of B. Leffler (2001).

We subsequently acquired the Canon PowerShot S230, which has a 2048x1536 CCD for 3 megapixel resolution, and we modified the radio-controlled rig to fit either version of the camera. Our results with digital KAP are quite satisfactory, and this camera has become our first to utilize for routine field work. Image resolution is comparable to 35-mm film for most purposes. The digital pictures are bright with good color balance and require little enhancement for display or printing. The digital capability means that pictures can be reviewed immediately after each flight to determine if the mission was successful. However, both these models suffered from relatively slow shutter speed, which resulted in a high proportion of blurry images.

In 2006 we upgraded the elph series to the Canon PowerShot SD600, a six-megapixel camera with high shutter-speed capability (ISO 800). We built a new cradle to hold the camera and added a sturdy frame with shutter trigger. This camera records a high percentage of sharp pictures. Photo date 4/06.

Canon Digital Rebel SLR (2004)

For professional-grade digital images, our choice is the Canon EOS Digital Rebel SLR-style camera with 6.3 megapixel resolution. Lenses are interchangeable with the Canon Rebel (film) camera, which gives great flexibility for KAP applications. We normally operate the camera with a zoom lens set to 18 mm focal length (~28 mm film equivalent) for wide-angle shots. With a 256 Mb memory card, up to 80 high-resolution pictures can be stored. Once again, Brooks Leffler built a superb camera rig with electronic shutter control.

Canon Digital Rebel KAP rig by Brook Leffler. Total weight of rig and camera with zoom lens (as shown) is 47 oz (1.33 kg). Photo date 7/04.

As with other SLR cameras, various lenses and filters can be utilized for special effects. A lens with 10 mm focal length produces super-wide-angle images, for example, equivalent to a 16-mm lens on a conventional 35-mm film camera. Another interesting effect is a panoramic image built from multiple, overlapping photos.

This camera rig is relatively heavy, especially with the large 10-mm lens; thus, it requires a large kite flying in a steady, strong wind. Operation of the radio-controlled rig is quite smooth, and a "fast-shutter" mode is most notable for achieving a high percentage of sharp pictures in spite of camera motion.

Canon S70 (2005)

Our favorite digital camera is the Canon PowerShot S70. This is a compact model with a 7-megapixel CCD. It has an excellent glass-molded aspherical zoom lens with true wide-angle view (28-100 mm film equivalent). Like the digital Rebel SLR, it has a fast-shutter mode which results in sharp, clear images even with substantial camera motion.

Canon S70 camera rig in flight. This rig is based on the robust titanium frame built by Brooks Leffler originally for a film camera. We constructed a new aluminium cradle to hold the S70 camera, and we added the gent360 to stop pan creep. Total weight of camera and rig is 28 oz (0.8 kg). Photo date 7/05.

This camera combines compact size and light weight with advanced photographic capability. It quickly has become our most useful camera for many applications, particularly expansive landscape views. With a large (1 GB) memory card, it can hold ~150 high-resolution pictures (3072x2304 pixels). The large image size facilitates many digital or print options for editing and display. However, a fast computer with plenty of memory is necessary for effective processing.

Tetracam ADC (2008)

The Tetracam Agricultural Digital Camera is designed to photograph green, red, and near-infrared portions of the spectrum, specifically 0.52 to 0.92 痠 wavelength, at 2048 by 1536 (3 megapixel) resolution. The camera employes a special lens to transmit near-infrared radiation, and blue light is excluded. The resulting pictures are false-color images: green appears as blue, red is shown as green, and near-infrared is red.

Tetracam ADC.

Based on a basic KAP kit from Brooks Leffler, we built a radio-controlled rig to operate the Tetracam ADC camera. The rig has full manual control of camera tilt, pan, and shutter button. The camera itself is approximately the same size and shape as an SLR-type camera. The main drawback is camera weight, which comes mainly from 8 AA batteries. Eight conventional alkaline AA batteries weigh about 6.5 oz (~185 g); whereas 8 AA lithium batteries are only about 4 oz (~110 g). Thus, replacing alkaline with lithium batteries reduces weight substantially and provides longer-lasting power. We rejected rechargable AA batteries, because of lower output (1.2 v) compared with standard batteries (1.5 v). Total weight of the camera, rig, and batteries is 37 oz (just over 1 kg).

Tetracam ADC camera rig built with some customization from the basic KAP kit by Brooks Leffler. Photo date 6/08.

Color-infrared photography was initially developed during World War II for camouflage detection. Important scientific applications include vegetation, soil, and water resources. In this format, vegetation appears bright pink and red, because photosynthetically active (green) plants strongly reflect near-infrared radiation. Water bodies, in contrast, strongly absorb near-infrared energy, regardless of water depth or turbidity. Because blue light is excluded, shadows appear quite dark. Thus, many color-infrared pictures have high contrast between bright vegetation and dark shadows and water bodies.

Upon launching the Tetracam camera rig, the crew takes a self portrait. Active vegetation appears in pink and red colors; vegetation is highly reflective for near-infrared, so is much brighter than normal and appears somewhat fuzzy. Note that vehicles and fence poles are sharply defined. Photo date 6/08.
View over Nature Conservancy marsh in central Kansas. Water bodies are quite dark in color-infrared format, regardless of water depth or suspended sediment, although some sun glint is visible in the foreground. Photo date 6/08.

Our biggest problem for operating this camera routinely proved to be adjusting the lens focus and zoom properly. Considerable trial-and-error testing was necessary to achieve suitable field for view and focus, which are fixed with locking thumb screws on the lens. The image file format is proprietary, and special Tetracam software is necessary to process and display the false-color images.

Return to KAP equipment or KapHome.

	Upon launching the Tetracam camera rig, the crew takes a self portrait. Active vegetation appears in pink and red colors; vegetation is highly reflective for near-infrared, so is much brighter than normal and appears somewhat fuzzy. Note that vehicles and fence poles are sharply defined. Photo date 6/08.
	View over Nature Conservancy marsh in central Kansas. Water bodies are quite dark in color-infrared format, regardless of water depth or suspended sediment, although some sun glint is visible in the foreground. Photo date 6/08.