Notes on Kite Aerial Photography: Background
In June 1997 Jeff Peters posted the following request to the Kite Aerial Photography discussion page:
"As a kite lover, this whole concept of kite-borne photography fascinates me. I'm cobbling together a perception of what it's all about by lurking around several pages, but some of the logistics are still a bit puzzling. If you have the time and inclination, could you (any of you) take me on a "virtual flight" by describing your setup, launch, shoot, and retrieval methods?
I'm most interested in how to establish a stable platform to which one would actually trust a camera."
This page is contains my response.
Jeff,
I kept your request for a description of a typical KAP session in mind as I went out yesterday. The winds were more brisk than typical for us but I thought I would write it up anyway.
It is a sunny Saturday morning and while tending to a few computer chores I also check the Bay Area Winds WWW page to see how the day is developing. Like most of our summer days there is a developing sea breeze, this one coming from the northwest as opposed to our usual westerly flow -- must be a weather front out there somewhere.
My KAP gear is already packed and in the trunk of my VW Cabriolet. The batteries were charged toward the end of the last session so they are ready to go too. Around noon I pick the Sonoma Valley, north of San Francisco Bay, as the target and head out. I’m solo today because Claudia and Charlie have gone to pick Thomas up at camp. During the delightful top-down drive north I’m watching the trees, water surfaces, etc. to get a sense of the wind.
Road shot on the way to Sonoma. This doesn't have
much to do with KAP be what the heck -- I like it so here it is.
My VW provides the red in the image as reflected in the big rig's
chrome wheel (21K jpg, Olympus D-300L digital camera,
June 1997)
My first stop in Sonoma is
Aeroschellville, a flight instruction and biplane ride company
operating out of a small civil airstrip. Aeroschellville flies
the Stearman PT-17 featured in a gallery page last October. I stop and chat with these pleasant
folks for a while (and they agree to barter an aerobatic flight
for a nice print!) while I watch and then measure the local
winds. The winds are strong (12 mph sustained with 20+ mph gusts
at ground level) according to my nifty, new Kestrel anemometer.
The last time I was at the airport I’d seen a handsome Swift
(a two-place, low-wing 1946 airplane) and today Tom Numelin, the owner, shows up. After a bit of
explaining my methods and intentions he agrees to roll the Swift
out on the tarmac for photos.
A ground shot of the lovely 1946 Swift. This plane
was produced in limited quantity following WWII with the hope of
appealing to de-commissioned military pilots. This Swift has an
attractive polished metal finish with blue paint trim. (19K
jpg, June 1997)
One of the Aeroschellville crew
goes to secure permission from the airstrip manager (granted with
a flight window to 150 feet). Tom goes to get the Swift. I pull
my car around to the likely anchor point for the kite (as I often
tie off to the car’s roll bar.) I pull out the KAP gear bar
and from it select the five things that begin each KAP session:
It takes less than a minute to clip the fuzzy tail to the kite’s harness and to clip the kite’s bridle to the kiteline. With glove on I launch the kite and spool out a quick 100 feet of line. I then take a climber’s strap and carabiner from the photographer's vest and secure the strap to the VW roll bar. The kiteline is then easily attached to the carabiner with a single-handed clove hitch. I usually wait ten minutes at this point to just watch the kite flying. I basically want to make sure it is stable and consistent ("happy" in my terms) before trusting the camera rig to it. On this occasion the Sutton 30 is not particularly happy. It is pulling like a mule and moving laterally (+- 20 degrees) when it loads up under the frequent gusts. So after 3 minutes I take the Sutton 30 down (by walking the kiteline hand over hand since there is plenty of room on the tarmac) and send the Sutton 16 up. It too pulls vigorously and flies from side to side in the frequent gusts but is better matched to the wind and will be easier to hand hold when flying the camera. I begin a second 10-minute waiting period.
I talk about the shot with the owner and we pick a clean strip of pavement for the "background" and orient the plane nose to the sun. The Sutton 16, though behaving somewhat erratically, convinces me it can lift the Canon Rebel rig without mishap. It will be a challenge to avoid motion blur in the images. I would normally send the kite much higher before attaching the camera to see if I could find smoother air at 300 or 400 feet. But this strategy at is not prudent at an airstrip and, besides, we would have to seek additional permissions.
From the KAP gear bag I pull:
I spend a minute getting a fresh roll of film into the Canon and the lens hood mounted on the lens. Then I complete a quick ground check of the radio gear by powering up the receiver first. One indicator of someone using the same transmitter frequency within range would be unbidden (by me) movement in the rig while my receiver is on and my transmitter is still off. Convinced the frequency is clear I turn on my transmitter and check the cradle’s rotation functions.
One
of my kiteline "Hangups". I now have over 100 flights
using this attachment system and I am quite happy with it. My
thanks again to Brooks Leffler who developed the geometry and
shared it with us via an article in the Aerial Eye. (19K jpg,
June 1997)
I now head back to the kiteline
and walk down around twenty feet of it. From the
photographer’s vest comes a Hangup and by taking the
kiteline’s load in my right hand I quickly attach the Hangup
to the slack line downstream. I attach a second Hangup six feet
down the line from the first. Also from the vest comes my Picavet
suspension. (Here I assume you are familiar with the Picavet
suspension, if not see my Picavet page.) I normally store the Picavet in a
plastic bag to keep its line in order. The line threads back and
forth between cross and line attachments eight times and will
make a very convincing knot if you give it a chance. When not in
use I clip the Picavet’s two kiteline attachment swivel
clips to eye screws in both ends of a 6" wooden dowel then
gather the lines between cross and dowel and chain stitch them
together. I now attach the Picavet by reversing this storage
process, unzipping the chain stitch, and attaching the swivel
clips to split rings on the Hangups. I always take a few seconds
to test the structural integrity of the Picavet by pulling on it
with several times the force expected of the camera cradle.
My current Picavet suspension as it comes out of the
pocket. The Picavet lines are chain stitched together to prevent
an otherwise inevitable knot of the devil. The wooden dowel with
eye screws helps keep the kiteline attachment ends of the Picavet
from tangling. (19K jpg, June 1997)
This day’s circumstance is a
good one for addressing your question about how one
"establishes a stable platform to which one would actually
trust a camera". Even though the kite is quite active a
hundred feet up, the movement at the Picavet is modest. This is
part due to the stretch of the dacron line absorbing load but
mostly just the geometry of having the Picavet within 15 feet of
the kiteline’s anchor point. When launching I always attach
the Hangups in a position that places the Picavet cross just
within reach – say about eight feet above the ground. Even
if, after I attach the camera, the kite dives 50 feet the camera
would still be above the ground. So I proceed by attaching the
camera cradle to the Picavet and making a final check of rig
movement functions and the camera’s settings (auto-exposure
mode, focus on automatic).
Once the camera is hanging from
the rig I unclip the kiteline from the carabiner and gain a
little working height by letting out kiteline. As stable as the
launching arragement is I generally feel better when the camera
is clear of the ground. With the camera rig about thirty feet
above the ground I work with the Swift owner to take a series of
plan view and oblique shots of the airplane with the camera
gaining no more than 40 feet of altitude (as monitored by a IR
laser rangefinder.) The owner helps me sight the camera
cradle’s position downrange – something my twin sons
usually attend to. The camera cradle is bouncing around quite a
bit in the gusty winds and my shutter speed is varying between
1/250 and 1/500 second (checked when the camera was on the
ground). The trick in this situation is to patiently await for
the moments when the camera cradle becomes less active and shoot
in these interludes. This I do and when the rig is moving
vigorously I back away from the handsome Swift lest something
fail and – bombs away. I will knock on wood and say that
I've yet to drop anything in several hundred flights.
Tom and his Swift in near plan view. The shadow of
the camera rig is visible near the plane's tail (25K jpg,
Canon 24-mm lens, June 1997)
With the photographs complete I tie the kiteline off to the carabiner again and walk the kiteline down to retrieve the camera rig. With the kiteline under my armpit I easily handle the Picavet without putting tension on its lines. After camera cradle removal the kiteline is released and the kite flies from the carabiner while I put the camera rig out of harm’s way (or on other occasions change film then reattach.)
With the camera tucked away I
walk the kiteline down again and remove the Picavet then the
Hangups. These go back into their photographer’s vest
storage positions. Next the kite is hauled in (by walking the
kiteline down in this case) and kite, tail, and kiteline stowed
away. A final scan around the flying site for scattered gear is
followed by stowing the larger items including the
photographer’s vest in the KAP gear bag. The session ends by
taking a couple of ground-level context shots, thanking the Swift
pilot, and exchanging business cards. Total time between hauling
out the KAP gear bag and placing it back in the trunk was around
35 minutes.
One of the ground-level context shots. These prove
useful when putting a gallery page together. (24K jpg,
Canon 24-mm lens, June 1997)
It is my hope that I can trade
Tom a nice print for a ride to Pt. Reyes. I'll let you know how
that turns out.
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All rights reserved. Revised: 25 March, 1996
URL: http://kap.ced.berkeley.edu/background/typical_session.html