CHDK How to get it

Put simply these are the steps...
1. Determine which firmware version your camera is using.
2. Download the correct CHDK zip file from the CHDK website.
3. Unzip and copy the CHDK files onto a freshly formatted SD card.
4. Lock the card, put it into your camera and CHDK is ready to run.

Sounds easy but there are a few hurdles along the way.
The CHDK website has instructions or you can use Dave Mitchells ACID and SDMinst apps to do it all for you.

ACID looks at a photo taken with your camera to determine the firmware version, then searches for any suitable CHDK builds.

CHDK builds come in different states of reliability. STABLE is tried and tested, TRUNK and the rest are like Beta versions (I think). Anyway choose the STABLE one if available, if not try one of the others. ACID can then download the CHDK file to your computer. It will be a zip file.

Unzip the downloaded file and move all the resulting files into a folder. You will need to select this folder when using the next app - SDMinst.



SDMinst formats your SD card and copies over the necessary CHDK files.

Some of the options in SDMinst can be confusing to the uninitiated.
If your camera can use cards larger than 4GB then you can untick "Create Partitions" and tick "Make FAT 32 bootable" That worked for my S100.

Older cameras use FAT16 formatted cards and may need partitions. Luckily I didn't have to deal with that.


UPDATE 8th Dec 2012: Dave has written 2 more apps to make the installation even simpler. What a guy! STICK for CHDK, and ASSIST for SDM.

There's a donation button on his webpages, I urge you to click it if you like his apps.

CHDK overview

OK, take a deep breath and buckle in. It's time to delve into the shadowy world of CHDK or the Canon Hackers Development Kit.

I am a CHDK novice but I find it quite thrilling and subversive.
CHDK means different things for different users, but for me it means I can make my Canon S100 automatically shoot at set intervals by running an intervalometer script. I have mine set at one shot every 5 seconds. Perfect for KAP.

CHDK is a firmware hack that is loaded onto your SD card and over-rides the cameras firmware when it is turned on. It doesn't change the firmware permanently, just while that particular SD card is used and the camera is on.

The correct version or "Build" of CHDK must be downloaded from the CHDK website for your particular cameras firmware. Mine is S100-101b. They are not interchangeable.

Once CHDK is running on your camera you will see extra icons on the LCD. They can be quite ugly and obtrusive but the extra functions given to the camera make it worth while.

Initially it was conceived to give DSLR-like functions (RAW, live histogram, exposure bracketing) to compact cameras but it also allows scripts or mini programs to be run. The intervalometer script is the main reason I use CHDK.

The images below show how the camera screen changes when CHDK is loaded.

Here's my default Canon S100 screen and the normal Canon Menu

The SD card needs to be locked for CHDK to load up when the camera is turned on. This seems odd but that's how it works. With an unlocked card the camera just operates normally.

When CHDK is loaded correctly the splash screen appears first then the S100 screen appears with extra icons overlaid. It is possible move and hide the icons if you want but don't worry about that just yet.

To get to the CHDK menus you push the review button to change to <ALT> mode, then push the MENU button.

This is the Scripting Parameters screen where you choose a script. e.g. Intervalometer, and enter details like the interval e.g. 5 seconds

Now, as long as you are in <ALT> mode the Intervalometer will start when you push the shutter button and stop with another push.

Here's a video demo of CHDK.

That's it really. In the next post I'll cover how to find the correct build, download and copy to the SD card.

KAP rigs - RC Canon S100

The Lumix LX3, a superior compact camera, was soon to be reclaimed by it's rightful owner (wife) so it was time to find a replacement.

Using the camera feature search on DPReview I looked for any compacts with 24mm wide zoom and intervalometer to replace the shutter servo. The only camera currently available fitting the search was the Lumix LX7 weighing 298g, a little too heavy for light weight KAP.

An alternative option was to add intervalometer function to a Canon compact using the CHDK firmware hack. The Canon S100 looked interesting, with GPS, only weighing 190g and A$100 less than the Lumix.

DWI  had the S100 for A$280 which was fine by me. I tend to think of KAP cameras, like underwater cameras, as expensive disposables.

Canon Powershot S100 RC rig - 460g

I am finally happy with this setup.
- CHDK/SDM intervalometer (explanation coming soon)
- Proportional pan and tilt using Turnigy 380MG mini servos
- Brooxes compact picavet and tripod bolt from the KAP shop
- Fibreglass face plant protection bar
- Safety leashes on the camera and tripod bolt

Proportional pan servo

A more logical method for pan is to use a larger gear on an unaltered servo with a smaller gear on the pan bolt. With the correct ratio (5:2 in my case) you can achieve +/- 180º rotation (=360º)  from a +/- 45º servo.

Also by changing the transmitter pan lever for a rotating pot or variable resistor (more about that later) you can make the rig pan position match the transmitter pan knob position.

This means you always know which direction the camera is pointing by looking at the transmitter pan knob.

A note of caution. Small movements of the pan knob give large movements of the rig. You need to be prepared for a sudden rotation of the rig when it is turned on. It's a good idea to turn it on to align the rig before hanging from the kite line and with no tension on the picavet. This way the picavet will spin on start up rather than the rig.

Continuous rotation pan-servo hack

The ratchet pan system needed constant adjustment to keep operating so I decided to change to a continuous rotation pan servo with gearing.

Servos are designed to rotate +/- 30º to 45º but with a simple hack they can be made to rotate in either direction continuously. All that's required is to open the servo, cut out a couple of little plastic tags and drill out the inside of the lower part of the spline. Here's a full explanation of the hack from the KAPER e-magazine.

Gearing down is a good idea to reduce the speed of panning, so a large gear on the pan bolt is meshed with a smaller gear on the servo. This rig used 2:1 ratio but 4:1 is recommended.

One issue you may need to deal with is servo creep. Some continuous rotation servos will not stay stopped no matter how much you adjust the trim switches. James Gentles makes an antiCREEP unit that solves the issue for standard servos. It gives a wider "no movement" zone and slower rotation overall. Unfortunately I found the hacked Turnigy servos did not work well with antiCREEP. The "no movement" zone became too wide.

This three legged rig with continuous pan micro servo and standard tilt servo weighed 560g all up, but suffered from pan servo creep.

Another issue with continuous pan is that you can easily lose track of which way the camera is pointing unless you use a video downlink (extra weight and expense) or some sort of pointer on the rig that is visible from the ground.

Jittering tilt servo

In the never ending quest for a lighter rig I tried some metal geared micro servos. The tilt servo directly supports the camera so it needs a strong metal spline.

This first servo I tried was a Turnigy TGY 113MG servo weighing 12g (a Futaba S3003 weighs 36g) and has metal gears and spline. Torque rated at 1.8kg/cm.

Unfortunately it was not strong enough to tilt 270g of camera, cradle and shutter servo without breaking into crazy jittering, shown in this video.

Even making sure the camera and tray were accurately balanced didn't improve the jittering.

I needed to find a light mini servo with more torque.

The Turnigy 380MG mini servo, 16g weight and 3.5kg/cm torque turned out to be the answer. It has a funky see through purple casing, standard Futaba sized spline with 3mm thread and no jittering.

KAP rigs - RC Carbon fibre tube

The Flickr KAP gear group is a fantastic resource for researching rig designs. There are many different styles of backyard and commercially made rigs but the one that really caught my eye was this one by Eric Kieboom.
Made for the Lumix LX3 using 4mm carbon fibre tube and various aluminium profiles it weighs almost 300g lighter than my first effort. As soon as I saw it I decided to ditch the heavy al rig and use carbon fibre tube. Back to the shed.

Lumix LX3 Carbon fibre tube RC rig - 600g

Here is my first version. The biggest challenge was finding the small aluminium extrusions. The square profile used on Erics corners and pan bolt support was not available in Australia. So I used 10mm tube which made accurate parallel drilling very difficult. Carbon fibre tube is available from Carbon Fiber Australia through their online store. 4mm x 1m tube A$5.95 each plus A$10.45 post.

Eric used CA glue (superglue) but I had some problems getting good adhesion so changed to epoxy.

I also bought a 4ch 2.7GHz radio from Hobbyking.com for A$28 (it works perfectly!) and added a mini servo for the shutter. The plastic mount for the shutter servo slots into the camera hotshoe and flexes when the servo pushes down. This prevents over stressing the servo.

This video shows it in action.

All up weight now 600g with 4 x AAA batteries. More weight could be saved by using mini servos.

KAP rigs - RC 3mm aluminium

At the other end of the complexity range is the full radio controlled rig which is heavier than a manual rig because servos, receiver and batteries are included.

Panasonic Lumix LX3 Aluminium RC Rig - 745g

This was my first RC rig, made from 3mm x 35mm aluminium resulting in a flying weight of 745g. (Flying weight includes everything hanging from the kite line)

The LX3 does not have an intervalometer or IR remote so the only way to shoot is by pushing the shutter button.
My existing Futaba radio was only 2 channel but I needed tilt, pan and shutter control. I devised this system using one servo for two controls, down to move the pan ratchet and up to shoot, with the other channel for tilt. I used standard Futaba S3003 servos and 4 x AA batteries resulting in a rig that worked but was way heavier than it needed to be.

A stiff breeze was required to lift the rig with  constant tweaking to keep the pan/shutter link working.

Building this rig was a good learning experience. The first lesson learned was that 3mm Al is way too thick. 1.6mm would be plenty strong enough.

Soon after completion I saw a carbon fibre tube rig and decided that was what I had to build next.

KAP rigs - Manual

Over the next few posts I'll explain 3 different types of KAP rig starting with the most basic manual rig.

The camera mounts onto a simple tilt/pan bracket, which must be pointed in the right direction before launching. Photos are captured continuously using the intervalometer or timelapse function.

 Canon Powershot S100 manual rig - 300g (including camera, rig, picavet and lines)

The S100 is not supplied with it's own intervalometer so the CHDK firmware tweak is necessary. The mounting bracket is 20mm x 1.6mm aluminium.

Camera and rig need to be balanced for the rig to hang perfectly level. Positioning of the tripod mount hole, picavet bolt hole and tilt axis are important.  Here's a page explaining how to find the centre of gravity written by James Gentles, a very clever KAP electronics inventor.

Manual rigs are the simplest and lightest setup allowing KAP in light winds and with the least stress. Great for targeting a specific subject but pre-flight aiming needs to be accurate. The camera must be retrieved to make orientation changes.
This is my favourite rig, very light and simple. In a steady 5kn+ wind the Levi Delta will lift it with hardly any pull on the line. I can walk around to position the camera where I want it and easily wind in or let out line.

GoPro HD2 manual rig - 260g

The GoPro with a tripod adapter bolts directly to the picavet upside down and images are inverted via GoPro menu selection. More than one mounting hole on this picavet allows the rig to be levelled for different camera tilt positions.
This is my lightest rig weighing 260g, used for flying from a dive boat and in light or unreliable winds. The camera is tough and well protected in its waterproof housing and has a fisheye lens. I tend to crop and "defish" the images in Photoshop for a more realistic result.

This rig could be made lighter still by removing the filter holder, but it is needed to hold a flat filter to allow underwater focus.

Hang the camera - Picavet

Usually the camera doesn't attach directly to the kite but hangs 20m or more lower down the line on a picavet self levelling system, named after french inventor Pierre Picavet. This keeps the camera steadier while the kite moves around. The picavet is a cross with 4 pulleys or holes through which 4 lines pass. The 4 lines are gathered at each end and attached to 2 line hooks which hang from the kite line. This allows the line angle to change while the camera stays level.
Here's an animated demo of how it all works from the Kaper website.

This picture shows my line hook bent up from thin coat hanger wire.

Ready made line hooks and picavet kits are available from The KAP Shop

The top 2 picavets are made from UPVC plastic, cut and heat moulded to shape. The bottom one is from the KAP shop. The picavet can be used with or without pulleys but they make the action smoother and quicker to level. I used Ronstan Kite Blocks costing about A$8 for a pack of 2.
More expensive and lighter Pekabe model boat blocks are another option.


Weight is always a consideration when building KAP rigs. A lighter rig can be used in a wider wind range and with less pull on the line.

My 4 picavet lines are each about 1.8m long, which allows the camera to hang about 90cm below the kite line with the 2 line hooks about 1.2m apart. The suspended ring prevents rotation.

Some KAPers use one length of continuous line to thread the picavet. Either way works well.

This photo shows one of my rigs hanging from the line of a PL 2m2 Pilot

First you need a kite.

To lift a camera you need a big kite with lots of pull. It also needs to be a steady flier and there are a few designs renowned for their KAP-ability.

PFK Nighthawk
The Paul's Fishing Kite (PFK) Nighthawk delta is designed to fly in winds as strong as 30kn. Most other kites would be looping and crashing by then. It has large trailing edge flaps, strong flexible fibreglass spars and a hardwood spreader. The KAP community has adopted the PFK as the strong wind specialist, but it will also lift lighter rigs in normal wind strengths.
This is my favourite kite, it just wants to fly and keep on flying no matter how strong. Tail usually not required but may calm it down a bit in strong winds and reduce overflying.

Lifting range
480g RC rig in 12kn - 30kn+
270g GoPro rig in 6kn+
NZ$140 from Paul's Fishing Kites - New Zealand

ITW 9ft Levitation Delta
For lighter winds 5kn -17kn, this big delta from In-to-the-Wind is my choice and a favourite of many KAPers world wide. It has more pull than the PFK but also starts to fly to the side and do power loops in wind speeds above it's range.
Flies at a very high angle and even over-flies in light puffy wind and hot days. Adding a tail reduces overflying and gives steadier flight. I use a 3m long tube tail.

Lifting range
480g RC rig in 8kn - 17kn
270g GoPro rig in 5kn+
US$75 from Into the Wind - Boulder Colarado




PL Pilot 2m2

This 2.0 square metre parafoil is made in New Zealand by Peter Lynn Kites. Peter Lynn is famous for making some of the world's largest kites.
Parafoils have no spars and pack up into a small stuff bag. They have strong pull but fly at a lower line angle like 50º
Flies well without a tail but everyone else says they use one. May calm down side to side swaying.

Lifting range
480g RC rig in 10kn+
270g GoPro rig in 6kn+
NZ$96 from Peter Lynn Kites - New Zealand




Cody Box Kite
This was the first kite I bought for KAP and it was not all that suitable. Above about 16kn it flies out to one side and power loops. It has a narrower wind range than the above kites and take more assembly time but does have good pull. KAP range 8kn - 15kn
However it is an interesting kite in the sky and attracts attention. It flies well enough within its wind range.

A$79 from Kite Power - Geelong



UPDATES
18th Jan 2013: New kite added to the quiver.
Skydog 7ft Pirate Rokkaku

Feb 2013: Made a 2m white rokkaku

May 2013: Made a 1.7m yellow rokkaku

What is KAP?

Kite Aerial Photography

This what you get when you add a camera to a kite, maybe some radio controls or electronics and lots of shed tinkering time.

Images captured by kite give a rarely seen perspective, on a more intimate or human scale than traditional aircraft aerials.

There is a very active world wide online community of KAPers and some seriously clever inventors producing electronics, rig and camera control scripts and mechanical bits for KAP rigs.

Kites
Big stable kites are needed to lift the camera and rig. KAPers usually have a range of kites to cover different wind speeds and camera rig weights. More about that later.

Cameras
The lighter the better obviously. GoPro, Canon compacts and even small SLRs are popular. Mirrorless large sensor cameras are starting to feature too.

Canon compacts can also be enhanced via CHDK (Canon hackers development kit) and SDM (Stereo Data Makers) firmware changes. I'll write more about these later but basically some very clever programmers have written firmware enhancements which add functions such as intervalometers, RAW, HDR and bracketing.



KAP rigs

There are many different styles of camera rigs for kite aerial photography. Here are a few of the main types.

RC KAP - using radio control to operate pan and tilt and maybe shutter release.

Auto KAP - using pre-programmed electronics to replace the radio controls. AuRiCo (automatic rig control) is what I use. The rig performs a repeating sequence of tilts, pans and shutter releases by itself.

Manual KAP - where you set the camera orientation and shooting interval before launching. The kite needs to be brought down to make any camera changes.