The previous two articles were written to describe what KAP is. But this article and those that follow have been developed with a different goal: to teach you how to get started yourself. There are so many ways to do KAP and so many different types of gear that newcomers might find it difficult to sort out all the options. So these next few articles will be about describing those options and giving advice on which selections are appropriate for different purposes.
Just about any camera can be used for KAP but the choice of camera will influence most other aspects of the photographer’s KAP experience. The camera’s weight determines what sort of kites will be needed. It’s size determines the dimensions and type of rig that’s required. And the method used to trigger the camera will probably depend on the camera’s brand and model. So when putting together a KAP system for the first time, it’s best to start by selecting a camera, then choosing the equipment that will work with it.
Does this mean that you won’t be able to use other cameras for KAP after this first one? Not necessarily. Most KAPers find it easy to upgrade cameras within a particular product line. And some rigs and control systems are flexible enough to accommodate different styles of cameras. But there is a certain degree of “lock-in” once you start using a particular camera.
There are certain features that make a camera well-suited for KAP. But camera manufacturers don’t develop their products with this use in mind, so choosing a camera generally means accepting some tradeoffs. Nonetheless, there are some excellent options available today and the trend seems to be for cameras to get smaller and cheaper while producing better images every year.
Let’s take a look at the factors that affect the performance of a KAP system:
If we’re expecting a kite to lift this camera, it can’t weigh too much. Fortunately there is an abundance of small point-and-shoot digital cameras on the market that are ideal. The lighter a camera is, the lighter it’s rig can be and the smaller the kite that is used to lift it. If the idea is to have a system that is easy to carry in a backpack, you’ll want the smallest camera and rig you can find. (This will probably be paired with a Flowform kite that is also easy to pack.)
But it’s usually not necessary to use the absolute lightest camera on the market. Just about any point-and-shoot camera can be fitted to a KAP rig and lifted by a modest size kite. That is, a kite that’s small enough for the average person to handle comfortably.
Many photographers would prefer to use an SLR type camera, though, for their superior image quality and controls. While this isn’t out of the question, it’s not a good way to get started in KAP. An SLR camera, even one of the lighter ones, will require more lift to get airborne. That means using a bigger kite that’s harder to transport and set up. It also means working much harder to hold and control the kite while it’s flying. People who do use SLR cameras for KAP are not just serious photographers, they’re serious kitefliers as well. I don’t want to discourage anyone with that level of commitment from doing KAP with an SLR camera, but I still recommend starting with something smaller and using it to develop the expertise that’s so important with the heavier cameras.
Digital wins. Period. KAP is often a numbers game. The more shots you take, the more good ones you get and the more selective you can be with the results. Digital cameras can store hundreds, sometimes thousands of shots before they fill up. Film cameras only about 36.
Film cameras do, of course, have some characteristics that could be advantageous for Kite Aerial Photography. Medium format cameras, for example, can capture a scene with far higher resolution than most digital cameras. But these cameras are too heavy for most KAP applications and if any motion blur results from the kite’s movements, this resolution is wasted. Nonetheless, the master KAP photographer Nicolas Chorier has used medium format film in his work to stunning effect.
Film also finds a use in scanning panoramic cameras. George Lawrence used such a system in 1906 to photograph San Francisco from the air after the famous earthquake. And modern replicas of his 49 pound camera have been built to commemorate that accomplishment. But most of us won’t be attempting that sort of KAP.
For the KAP novice I can think of interesting application for film cameras. There are published plans for a KAP rig based around a disposable single-use film camera. The rig described by these plans is cheap and simple enough that it makes a great project for the classroom or a scout troop. But, while it makes a good project activity, it won’t be as productive as other KAP systems when it comes to capturing images.
So digital is usually the way to go. But not every digital camera is well suited for KAP. The cheapest digital cameras out there, such as pen cameras and web cameras, have a flaw that makes them less suitable for KAP. They typically employ what’s called a rolling shutter. The imaging chip captures one line of the image at a time, first the top line, then the second line and so on down to the bottom of the image. But if the camera is moving while it’s taking the photo, and a KAP camera usually is, this will result in wild distortion in the final image. “Ordinary” digital cameras expose all the pixels at once before reading out the data, thus avoiding that type of distortion. So if you’re trying to get nice images with KAP, it’s best to avoid web cameras, pen cameras and the like. On the other hand, if you have one of these cameras and want to check out the view from a kite, it should be quite easy to do since they are so small.
Most cameras on the market today use proprietary rechargeable Lithium Ion batteries. A few cameras, though, still take AA batteries. This gives the user the option to use standard alkaline batteries, rechargeable NiMH batteries or single-use Lithium cells. Having these options is good. If the rechargeable set isn’t charged for some reason, standard alkalines can be used as a backup. And they are readily available worldwide. Lithium cells, though more expensive than alkalines last much longer and are extremely light. The weight savings over other battery types can be significant.
Lets face it, some cameras take better pictures than others. A major factor influencing image quality is sensor size. SLR cameras generally have the largest sensors but, as we mentioned above, they are more difficult to use for KAP. Point and shoot cameras aren’t all created equally, though, so when choosing a KAP camera, it’s worthwhile comparing sensor sizes of the models under consideration. Generally smaller sensors will produce images with more noise and less overall quality.
One exciting trend in camera design is the new compact format cameras with SLR-sized sensors. These are collectivly referred to by the acronym EVIL, Electronic Viewfinder Interchangeable Lens. Initially there was the micro four-thirds system from Panasonic and Olympus. But other camera manufacturers have started to introduce similar models such as the Sony NEX-3, Samsung NX and Leica MX lines. These should be capable of producing premium quality images without the unnecessary weight of an SLR.
Another factor influencing image quality is the file format. Most point and shoot cameras only produce JPEG files. These have relatively little dynamic range and so can’t be adjusted and corrected as readily as RAW files. Cameras that are capable of producing RAW files are SLR’s and the EVIL’s mentioned above. Also Canon point and shoot cameras that support CHDK are capable of creating RAW files. Even when using a camera that supports RAW format, though, there is a penalty for doing so – RAW files can be 5 to 10 times larger than the corresponding JPEG files.
Some cameras are more desirable for KAP than others because of the way they are triggered. Virtually all cameras come equipped with a shutter button for triggering the exposure. Some also have infrared sensors that work with a wireless remote. Others have a port where a wired remote plugs in. In most cases, these remote ports are the preferred method of triggering the camera for KAP. So choosing a camera that supports an IR remote can lead to a cheaper, lighter KAP system.
Another method of triggering the camera that’s a fairly recent innovation involves a technology called CHDK. CHDK is a set of software that runs on certain Canon point and shoot cameras, temporarily overriding the camera’s own software. It enables the user to write short programs called scripts are capable of taking photos at fixed intervals or in response to a 5 volt signal on the USB power port. Owners of these cameras have found it’s a reliable way to trigger the camera and it adds no weight or cost to the overall system.
So no matter what type of camera you have, there’s a way to trigger it on a KAP rig. But some cameras support methods that are lighter, cheaper and require less power than others.
Let’s shift the topic now from what to look for in a KAP camera to how the camera is employed in a KAP system. We can start by taking a more in-depth look at these triggering techniques. For each one we’ll discuss when it is applicable and what are it’s advantages and disadvantages.
First we consider triggering the camera by simply pressing the shutter button. Since every camera has one, this is a universal approach – mechanisms that work for one camera will work for most others as well. The most common arrangement for pressing a shutter button is to have a servo motor positioned so that a little arm comes down and presses the button. Instead of an arm, the servo can be fitted with a cam mechanism. The primary advantages of this approach: it works where nothing else will. It can also let the control system take advantage of some special features found in most cameras: half-pressing the shutter button to acquire focus and holding the shutter button to shoot multiple frames.
But there are disadvantages of using a shutter servo, too. The servo itself contributes to the weight of the whole system. And it draws power from the rig’s batteries, shortening the rig’s endurance. Finally, there’s the cost. Most of the alternative mechanisms for triggering a camera are less expensive, lighter and use less power.
Now let’s consider alternatives to using the shutter button. Certain camera models support a remote control that works via infrared signals. Now it isn’t possible to actually use such a remote when the camera is on a kite – the distance is too great. But some KAP rigs incorporate a device that can generate the same IR signals, causing the camera to shoot. James Gentles has developed an entire line of products that work on this principle. There are devices that convert a servo control signal into IR codes, timers that generate IR codes at regular intervals and many other useful gadgets. These devices are extremely small, light and use very little power. They also tend to be less expensive than servos. What’s the downside? Only certain camera models support IR triggering. And, unfortunately, it seems this feature is being dropped from newer camera models even in product lines that used to support it.
Another type of remote trigger that is sometimes useful for KAP is the wired remote port. Typically this feature is found on SLR cameras, though. And most of those cameras also support an infrared remote mechanism. So it’s fairly rare to find a KAP rig that uses this method of triggering the camera.
CHDK
There is one more important triggering method yet to discuss: CHDK. CHDK stands for Camera Hacker’s Developer Kit. It’s a rather remarkable and useful innovation but it requires a little explanation. All digital cameras contain a microprocessor – a tiny computer that executes the software that makes the camera work. CHDK is a set of alternative software that can be loaded on certain Canon point and shoot models. It’s like a temporary software upgrade that enables a host of new features. But CHDK wasn’t developed by Canon, it was developed by a community of photographers and software engineers via the internet. It enables a camera to store images in RAW format. And it enables users to write scripts in a language called UBASIC to control the camera’s operations automatically. (There are dozens of other features CHDK introduces, as well, but these are the two that are most important for KAP.)
What that means is we can make the camera take photo automatically. Here’s how it works. First we prepare an SD card with the CHDK software and a script file. The script is a simple UBASIC program that does takes a picture, waits a few seconds, then repeats endlessly. We load this SD card into the camera and turn it on – the CHDK software takes control. We press the [which?] button to bring up a new CHDK menu. Using this menu, we select our script file as the active script. Now, when we press the shutter button, instead of taking a picture, the camera starts running the script. Under the scripts control, the camera shoots a picture, waits a bit, shoots again, waits, shoots, and so on. This continues until we press the shutter button again, signaling the script to stop.
UBASIC scripts for CHDK can be even more sophisticated, too. One useful feature of UBASIC in CHDK is it can sense the state of the power input on the camera’s USB port. So if want to use an R/C transmitter to trigger the camera, we can attach the R/C receiver to a special cable that plugs into the camera’s USB port. Then, when we toggle the switch on the R/C transmitter, that information is transmitted to the receiver, is converted to a voltage by the CHDK cable, is detected by the UBASIC script and the script tells the camera to shoot a picture. It’s a bit complex but it’s reliable. And like the IR LED technique, it’s lighter, cheaper and more efficient than using a servo to press the shutter button.
The disadvantages of CHDK: it’s only available on certain Canon camera models and it requires a certain comfort level with computer technology. It’s not actually necessary to be able write UBASIC scripts since there are scripts available for KAP already, but the steps of finding the appropriate version of CHDK for your particular camera and setting up the SD card can be daunting to some.
What options for tripping the shutter still remain? Just a few infrequently used ones. What about the interval timer that’s built into most cameras? Unfortunately for most cameras it only waits 10 seconds and takes one shot. That doesn’t make for a very productive KAP session. Some models will take multiple shots which is better but still not convenient enough. There are a few cameras on the market that have a built-in intervalometer feature that allows the camera to shoot photos continuously at regular intervals. But even these usually have a minimum period of around 30 seconds. We want something more like 5 to 10 seconds.
The final option to describe is opening up the camera case and attaching wires to the button contacts for the shutter button. Using some external electronics, it’s possible to then complete the circuit making the camera react as if the button was pressed. This technique is lightweight, cheap and power-efficient just like the CHDK and infrared methods. But it involves risking the integrity of the camera itself and requires quite a bit of skill and some specialized tools to pull it off.
Whew! That’s a lot of options for triggering a KAP camera: servos, infrared, CHDK, etc. How will you decide which to choose? If you happen to have a camera that supports an infrared remote, the IR approach is probably your best bet. If you have a Canon point and shoot camera that supports CHDK, then try taking advantage of that. If neither of those options fits your situation, you’ll probably want to use a small servo mounted over the shutter button to trip the shot. The other options like rewiring the shutter button won’t be used by most readers but they were described here for completeness
How to trigger the camera is broad subject, fortunately, how to mount it is an easier one. It’s virtually universal that all cameras have a screw socket for connecting a tripod mount. The threading of this socket matches a 1/4-20 screw. So just about every KAP rig has a 1/4 inch hole through which a short screw or bolt mates with the camera.
Some people also add a thin rubber pad between the camera and the base of the rig to which it attaches. This helps prevent the camera from twisting if it’s bumped.
Hopefully the material in this article has opened your eyes to the wide range of options for KAP cameras and how they are employed. Now it’s time to narrow that scope and help you choose a camera to get started with.
First, consider using a digital camera you already have. If you have any kind of point and shoot camera, it should be straightforward to build a KAP system around it. If you use primarily SLR cameras and want to do KAP with one of those, I would still recommend getting started with something smaller, then upgrading to the SLR once you’ve gained some experience.
If you don’t already own a camera you want to use for KAP, you’ll want to purchase one. Some of the best models for KAP are now discontinued but can be found on eBay. The Canon A570IS is a popular one because it runs CHDK, has great image quality, uses AA batteries and supports a wide angle adapter. Try reviewing the reference section for articles on particular cameras when evaluating other options.
Once you have a camera selected, figure out how you’ll trigger it: servo, IR or CHDK. IR should be your first choice if the camera supports it. Then it should be CHDK if the camera supports that. If neither option works out, you’ll probably want to use a shutter servo.
The next major decision to be made is what type of control system to use. That’s the topic of the next article.