Notes on Kite Aerial Photography: Equipment

KAP Rig No. 1
Yashica T4 Point & Shoot


A Radio-Controlled Camera Rig

KAP Rig No. 1 photographed in my living room,
March 1995 (34K jpg)

As related in the introductory pages for this web site, my first exposure to kite aerial photography was an encounter with Anne Rock at the Berkeley Waterfront. Anne kindly provided a brief tour of her equipment including the camera cradle constructed by 'Mr. Rock', an expert in aircraft maintenance. Anne's rig is a handsome creation incorporating a set of somewhat exotic materials (honeycomb panel and carbon fiber) related to aircraft repair. I spent some months trying to remember its details and pondering ways to translate the design into materials more common to my workbench. With great serendipity these imaginings were interrupted by the arrival of the Aerial Eye, Vol. 1, No. 1 - a KAP newsletter with a theme topic of camera cradles. This was enough to turn the wandering mind toward issues of destiny.

This page describes my first radio-controlled rig for taking photographs from kites. It directly follows suggestions by Brooks Leffler in the Aerial Eye and uses a Picavet suspension method dating to 1912. This rig is the apparatus used to take almost all of the photographs presented in this web site.

Information on the Picavet suspension is on a separate page.

 


A Plan Courtesy of the Aerial Eye

Diagram of Brooxes Better Brownie Box Mark VI reproduced from the Aerial Eye Vol., No. 1 , November 1994 (90K jpg)

In the Aerial Eye article, Brooks Leffler described the evolution of his KAP rigs and presented the most recent design, his sixth, in detail. The Mark VI might be characterized as a miniature rig that applies a standard receiver, small servos and a tiny ni-cad battery to rotate, tilt, and fire a small point-and-shoot camera. On seeing Brook's diagram (reproduced here with his permission) my immediate thought was "I can build this one" and over the Christmas break of 1994 I did exactly that. The rig has served me well ever since.



The Diagram Realized - My KAP Rig No. 1

Components of KAP Rig No. 1
September 1995 (36K jpg)

1. The central vertical axis with plan rotation gears
2.
Plan rotation servo
3. Attachment point for antenna
4.
Shutter release servo
5. Minolta Freedom Vista point-and-shoot camera
6.
Camera tilt servo
7. Radio receiver
8. 225-mAh, 4.8-V, high-capacity, ni-cad battery pack


This rig was made from aluminum angle stock and basswood. Going clockwise around the elevation view the first component is (1) a vertical axis made of 6-32 threaded rod (taken from a toggle bolt). The vertical axis provides the attachment between the camera rig and the Picavet suspension cross using a wingnut and washers. I used a thin bolt because of the small diameter gears used in (2) the plan rotation servo arrangement. Since servos only turn a fraction of a circle a gearing system was used to 'amplify' the rotational output of this servo. I used rather inexpensive gears sold as RC model car replacement parts. They seem to have worked fine in a 11-tooth (vertical axis) to 48-tooth (servo) ratio. This operation produces a bit of load so I selected a more robust metal gear servo. The unused portion of the larger gear is cut away. The rig has a cage to suspend the rotating portion of the rig from the vertical axis threaded rod.

The antenna shaft is attached to the outer frame (3) using a nylon cable bracket. I'm using an aluminum tube as the shaft with the antenna routed through its interior toward the rear of the camera. The remaining portion of the antenna is wrapped around the exterior of the tube and taped in place. The antenna tube provides my most important visual cue regarding the plan orientation of the camera when the rig is in flight so I'm thinking about switching to a bright arrow shaft. When storing the rig, the antenna tube and Picavet cross are detached to make a flat package. The shutter release servo (4) is a simple arrangement of sizing and attaching a stick to match the camera's shutter button position. This servo has low loads and thus normal (less expensive) internal gears. I have separate shutter sticks for the two cameras (5) I use with the rig (Minolta Freedom Vista and Yashica T4).

The camera is tilted with a direct-drive servo (6) since rotation from horizon to straight down can be achieved within the servos normal angular output. After developing a chipped servo gear, I changed the tilt servo to a metal gear model. The radio receiver (7) is attached to the rig's upper bracket with a rubber band. Power is switched by manually plugging and unplugging the battery cable. The rig's diminutive battery pack (8) is attached near the radio.


Servos for Camera Movement and Control

The rig's radio sends signals to small servomechanisms (servos) that in turn rotate a drive shaft through about 100 degrees full range. This rotation can be converted into movement of the camera or shutter button by developing a linkage from the servo's output arm to whatever seems appropriate. For this rig I followed Brook's lead and used tiny micro servos (the Hi-Tec HS80). These run about $30 each (or $40 with metal gears, recommended). They are desirably compact and have performed well.


Detail Views

The plan rotation servo and gearing ,
September 1995 (52K jpg)

In this image you can see the servo's larger output gear and (just barely) the smaller gear it drives against on the rig's vertical axis. The aluminum frame, made of scrap material, positions the gear on the vertical axis and supports the suspended rig.

back to key diagram



The camera tilt servo,
September 1995 (39K jpg)

The camera tilt servo establishes the vertical attitude of the camera through direct drive. Note the camera is mounted upside down in the lower bracket of the rig. The resulting photographs can of course be viewed rightside up.

back to key diagram



The shutter release servo,
September 1995 (42K jpg)

The shutter release servo rotates a stick to depress the camera's shutter button. The necessary rotation is so small that a trim tab (fine tuning control) on the radio transmitter is used to fire the shutter.

back to key diagram



The radio receiver and its battery pack,
September 1995 (19K jpg)

The battery pack is mounted above the upper bracket cross piece with the radio immediately below it. Both items are held in place with a single #64 rubber band.

back to key diagram



Other pages at this site describe a low cost rig designed around a disposable camera and Wolfgang Bieck's rig carrying a Minolta SLR with external motordrive. The images on this page are stills captured from a Hi-8 camcorder tape by a VideoSpigot board.



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Comments to author: crisp@socrates.berkeley.edu . All content, graphics and
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All rights reserved. Revised: Saturday, June 26, 2010


URL: http://www.ced.berkeley.edu/~cris/kap/equip/kaprig1.html