Second Wind

Over on the kite discussion page Pierre Lesage asked for help with an infrequent but nevertheless vexing KAP problem.

“What is the best way you have found to bring down the kite line in a heavy wind situation when you cannot “walk” the kite down? (standing on a small platform or too many obstacles to walk it down) The problem is not tying the line but really to bring it down easily and safely, are there any tools (besides a figure eight) used by alpinists that may be used with a kite line? I find that tangling the kite line around the hand with 25 kilos of pull even with gloves is potentially dangerous.”

I think of this as infrequent because one generally selects a kite to match the wind – enough pull to lift the rig but not so much as to make handling difficult. I immediately thought of an ingenious approach taught to me by Henry Jebe. Read on to learn about the technique.

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For five years now I have been shooting almost exclusively with digital cameras. This works quite well for me. My various Digital Elphs have been compact, robust, and lightweight. They have also been relatively affordable, take many images per flight, and relieve me of expenses for film and developing. Were I to complain I would note that the resolution of these cameras generally precludes making large prints, the tonality of the images suffers a bit, and blown highlights can be a problem.

Of late I have been working on stitching multiple images to achieve an image resolution that far exceeds the native resolution of my camera thus opening up the possibility of large prints. The technique ends up being easier than you might imagine since there are few foreground objects.

This last weekend I achieved my largest panoramic image to date, a 37,500-pixel-wide plan view of a quarter mile stretch of Pacific Beach in San Diego.

This little strip of image doesn’t look like much but if you are interested follow its link to Flickr and view the largest version (1/4 full size). It is a fun image to wander through.

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About a year ago I acquired a new radio for controlling aerial camera cradles that I lift using kites. For the previous ten years I used an Airtronics Infinity 600, a programmable transmitter that dated from my RC sailplane days. While it was well time to update this 1991 vintage radio, my principal motivation for change was concern about using the 72 MHz frequency assigned to RC airplanes. Recently radio control systems have appeared using the general use 2.4 GHz band, a frequency that is available for general use worldwide.

My new radio is the Spektrum DX6 from Horizon Hobbies, a product that is special for two reasons. First, it is the first commercially available system that operates in the unlicensed 2.4 GHz frequency band. Gone are concerns that I might interfere with RC aircraft and foreign travel for KAP is no longer a bother (at least in terms of radio frequencies) Second, the radio employs a digital spread spectrum technique to transmit the control signaling. In theory, and happily in practice, this technique isolates the Spektrum system from a 2.4 GHz environment that must be chaotically awash with signals from WiFi, Bluetooth, baby monitors, and remote-controlled tie racks. What could be better? The radio is programmable for 10 cradles and the system costs less than $200 new with receiver and four tiny servos But wait you say, surely such a bleeding edge technology will be idiosyncratic and trouble prone, good for early adoption junkies but not for me. After a year of use I can report the Spektrum has performed superbly as a KAP radio, nary a glitch to report.

You can find a detailed and interesting description of the Spektrum DX6 at the Spektrum DX6 Resource Center, a hobbyist’s site.

The stock Spektrum has the dual thumb stick geometry typical of RC aircraft radios.

Over the last couple of weeks I have worked on repackaging my Horizon Spektrum DX6 transmitter to allow operation with a single hand (left) while leaving the other available for handling the kite. I designed and made an umbilical hand controller for my old Airtronics radio, completing the project just before my shift to 2.4 GHz made it obsolete. This time around I decided against the umbilical approach and opted to reduce the size of the transmitter package itself while revising the control potentiometers and switches. The modifications have not altered the FCC certified 2.4 Ghz transmitting component.

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There has been of late an interesting thread on the KAP Discussion Page about ways to secure a camera cradle to its Picavet suspension. My camera cradles, as is often the case, have a vertical threaded rod rising from their center of gravity. This rod is typically attached to the center of Picavet suspension cross with a nut that can be finger tightened such as a wing nut. Should the nut become loose in the air you could be faced with the dreaded “bombs away” scenario. This does happen. Yikes.

A “longnut” made from an aluminum threaded insert. The red knob has been attached to one end with a small bolt and glue.

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Maker Faire in San Mateo has come and gone. It was great fun.

As noted in an earlier post, MAKE magazine featured KAP on the cover of its inaugural issue. I was unable to attend the first Maker Faire last year because it coincided with my KAP workshop at the College of the Arts in Philadelphia (where I met Dave Wheeler and Tom Nied). This year I put the event on my calendar and made it stick.

A pole aerial photography shot of the kite aerial photography booth at Maker Faire. My son Thomas is minding the store.

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For some reason it has always been agreeably easy for me to get stereo pair images to ’snap’ into 3D by crossing my eyes or going walleyed. I should probably credit the many occasions when I ignored my Mother’s “stop it — your eyes will freeze like that” admonitions. In any event, I often scan my images sets for views with nominally identical framing taken seconds apart. While conventional stereo pairs are usually captured by a two-camera setup, these serendipitous pairs are sequential frames from the same camera. Here is one that emerged from last week’s outing. If you have the knack for seeing with your eyes crossed this one ‘pops’ nicely.

UC Berkeley looking west

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We spent a pleasant Saturday afternoon at Pt. Reyes out toward Drakes Beach and Chimney Rock. A persistent marine haze was the major KAP story. My digital cameras really don’t do very well with haze under good conditions. So I worked on images that opposite the sun and took a large number of surf and ground texture shots pointed straight down.

The Drake’s Beach bluff looking east.

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I seem to be one a bit of a panorama jag these days and I think it relates to two specific shortcomings of my current digital KAP rig. My ‘go to’ rig these days is the Canon SD800is cradle. It is fun and convenient to fly. While I enjoy the camera’s relatively wide 28-mm equivalent lens it isn’t really wide enough for me. Back in the 35-mm film world I spent most of my time working with 24-mm and 20-mm primes. With a stitched panorama I can achieve that extreme wide angle view again.

A thin slice of the UC Berkeley horizon in a five-image stitched panorama.

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The Makers Faire event is not principally, or even in large part, about kites. But it should be a pretty cool gathering anyway.

This is the second year that the Makers Faire has been organized by the MAKE Magazine folks at O’Reilly Publishing. I worked with them way back when the magazine was a conceptual idea and developed an article about the Silly-Putty-timer-based cradle I designed at the Exploratorium. That article went on to be the cover story of their first issue (and is apparently included in their first Japanese issue).

Recently MAKE was selected for the Cooper Hewitt’s Design Life Now exhibit so a Delta Conyne kite, a Silly Putty cradle, and 20 or so kite aerial photos are on exhibit in that venue (until July).

The cover of the inaugural issue of MAKE magazine. My low cost rig was the cover story.

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There has been an interesting thread on the KAP Discussion page about motion blur and this led me to think about the keys to reducing motion blur. Many of these have come out in the comments – separate camera from kite, set aperture priority to achieve highest shutter speed, use a good suspension, Pekabe blocks help, and seek smooth winds.

My son Thomas Benton, a KAP neophyte, at the controls.

I think Scott K.’s comment in the thread is particularly on the mark and would like to second it. I recall fretting about blurred exposures in my early KAP days but then the blur issue seemed to go away. As experience built I think I intuitively learned a number of techniques to reduce motion blur.

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