Kite Aerial Photography, Experiment I
It all started when I saw <a href='http://www.rtpnet.org/robroy/lawrence/landscape.html'>these photos</a> that George R. Lawrence took of San Francisco right after the 1906 earthquake. He had been working on using kites as aerial photography platforms, and had nearly perfected his technique when the quake hit.
I had run across some other sites online where people had used kites and weather balloons as photographic platforms, and it really seemed like fun.
The last straw came yesterday when I saw that my friend and ex-coworker Mikel had been doing <a href='http://flickr.com/photos/mikel_maron/1278842/'>some experiments</a> with a power kite to lift a camera. His photos were great, and I had a whole day to play....
So off to do some research online. There are <a href='http://search.yahoo.com/search?p=kite+aerial+photography&ei=UTF-8&rls=org.mozilla:en-US:official&fr=moz2'>suprisingly many</a> resources online for information on this hobby. I read up on different types of kites (soft, structured) and how the size and design of the kite affects how much it can lift.
Another important component of using a kite to hoist a camera is how the camera is suspended from a kite. Some folks like to use a pendulum-type of arrangement to hold the camera level, but I liked the <a href='http://arch.ced.berkeley.edu/kap/equip/picavet.html'>Picavet Suspension</a> design. It is simple and lightweight, and not only holds the camera level, but very steady as well. It doesn't attach to the kite itself, but to the line -- at least 50 feet down the string from the kite for maximum stability.
So after some doodling, it was off to find a kite and to get the parts to make the Picavet. I went to <a href='http://www.djhobby.com'>D&J Hobby</a> to find the kite. I left with a <a href='http://www.newtechkites.com/ntk_product_profile.php?PSKU=55352'>New Tech Patriot Sky Hook</a>. It's a BIG kite -- 30 square feet of lifting area. Since it is a "soft" kite (no structural rods), it packs up into a very small space. You could fit four or five in a normal backpack.
After a stop at Home Depot to get some eye bolts, carabiners, aluminum plate, and other hardware, it was back home to the workshop.
<a href="/pictures/20050212-kitecam?0"><img class="thumb" align=right valign=top src="http://nobot.oceanairflightservices.com/20050212-kitecam/thumbs/CRW_7105-platform.jpg" /></a> The Picavet was easy to make -- I made the cross from some 1/2" birch plywood I had on hand, using a half-lap join in the center of the cross. I used 2" wide aluminum strip stock to make the camera cradle. It all went together pretty quickly.
The secret to the Picavet is how the string is threaded between the carabiners and the eye bolts on the platform. The suspension string is a single loop of line. I used a <a href='http://www.une.edu.au/~unemc/dbfish.htm'>Double Fisherm*n's Knot</a> to join the two ends of the string. Knots are cool.
After I got everything together, I checked the <a href='http://weather.noaa.gov/weather/current/KNUQ.html'>weather at Moffett Field</a>, a Navy/Air National Guard/NASA base next to Shoreline Park. The wind was blowing at 8 knots -- perfect!. So I drove out to the <a href='http://www.gwtw-kites.com/Shorelineparkmt.viewca.info.asp'>Kite Flying Area at Shoreline Park</a>. There were several people there. Some flying dual-line stunt kites, a guy doing some kite surfing, and parents with little kids and little kites. I sat in the car for a while to get a sense for how the wind was blowing and where I could set up.
After 15 minutes or so, I picked up the stuff and walked out to a remote corner of the kite flying area. I hadn't flown a kite for a long time, and definitely never one this big, so I was a little nervous. I figured I should fly the kite for a while before hooking up the camera to make sure I wouldn't be putting the G3 in danger.
I unrolled the kite and tied my line onto its bridle. Holding the bridle in one hand, I spread the kite out into the wind with the other. Immediately it took to the sky. Easy! I didn't have a proper kite-flying spool, just a ball of nylon string I got at Home Depot (intended for masonry work, I think).
The kite was a real handfull! It really pulled hard. It was very steady in the sky too. This was encouraging -- I had a good feeling I'd get the camera up there.
Letting more and more string out was pretty easy, I just had to relax my grip on the spool a tiny bit and it whizzed right out. After 10 minutes and a couple hundred feet of line, I figured it was time to reel it back in. Oh boy, I didn't plan for that. Without handles on the spool of string, this was a tough job. Needless to say, my thumbs were super tired after the 20 minutes of continuous winding it took to pull the kite back in.
I tied a couple of <a href='http://www.une.edu.au/~unemc/alpbutt.htm'>Alpine Loop</a> knots in the string 10 feet apart about 50 feet below the kite. These would serve as mounting points for the Picavet.
It was pretty tough after launching the kite to hold onto it with one hand and clip on the Picavet with the other. I managed after some struggling and a couple "choked" fingers.
Still holding on to the kite-line spool with one hand, I turned on the camera with the other. One <strong>excellent</strong> feature of the Canon G3 camera is its "intervalometer" feature. You basically tell the camera "take a picture every X minutes". This is perfect for kite photography, since without it you would need some kind of remote-control for the shutter release.
So with the intervalometer armed, I started letting out the line. It worked really well. The wind had died down a bit, and my hands were tired, so i didn't let the kite get out over 80 feet or so (meaning 30 feet of height for the camera). It did a good job though -- very steady.
<a href="/pictures/20050212-kitecam?1"><img class="thumb" align=right valign=top src="http://nobot.oceanairflightservices.com/20050212-kitecam/thumbs/CRW_7087-kite-and-cam.jpg" /></a> I tied the line to a nearby fence and used my other camera to take some photos of the rig in the air. Not once was I worried about damage to the G3 -- even when the wind would die down, it would float very gently lower. The camera did hit the grass on the ground a couple of times, but it was a super-soft landing.
<a href="/pictures/20050212-kitecam?6"><img class="thumb" align=left valign=top src="http://nobot.oceanairflightservices.com/20050212-kitecam/thumbs/CRW_6573-self_portrait.jpg" /></a> I figured out that I could bring the kite down easily by putting the line under my arm (near the fence where it was tied up) and walking out toward the kite. It was all slowly pulled to the ground. I did this a few times to lower the rig so I could re-aim the camera. After it was aimed, it was just a matter of lifting my arm to release the line, and it was back to the skies!
All in all, I'm pleasd with the result of yesterday's experiments. I would have been happy just to see how the kite flew, but it was so good that I was comfortable putting the camera up there. I'm really looking forward to more days and places with this rig! (Kauai, anyone?)