The Trackuino intervalometer is a Lua script that works on Canon cameras with the CHDK firmware. The idea behind an intervalometer is that the camera can take photos and videos of the flight while the tracker reports its position, and they both work independently. That way, if either subsystem crashes or runs out of batteries, the other won't be affected. It also means less work for the main controller, less interaction between parts, and less risk of failure.
Using the Trackuino intervalometer involves installing CHDK in your Canon camera. This is a perfectly safe and non-destructive process. The CHDK firmware resides in your camera's SD card. If you want to remove CHDK, you just format your SD card and your camera is back to normal.
- Can take photos AND videos alternately
- The duration of the videos, the number of photos between videos and the time between photos are configurable
- The camera can be pre-focused to minimize AF operation during flight
- Optionally turn off the screen to save power
This has been tested on a Canon A570IS, but it should be compatible with most Digic III point and shoots. Please report issues otherwise!
Provided you have CHDK installed:
Use the download zip button and unzip it to get the "trackuino.lua" file. Then, copy it over to the CHDK\SCRIPTS directory in your camera's flash card.**
To configure the intervalometer, start the camera in recording mode (not in playback mode). The dial mode is irrelevant. Press ALT (usually the "print" button), then MENU. Go to "Scripting parameters" and load up the script "trackuino.lua". You can change any of the parameters:
| Parameter | Values | Default value | Purpose |
|---|---|---|---|
| Mode | 0=photos+videos, 1=photos only | 0 | Mode "0" takes photos and videos alternately. Mode "1" takes only photos |
| Video length | Number of seconds | 30 seconds | Duration of each video |
| Pics between videos | Number of pics | 5 | This is the number of pictures taken between videos |
| Time between pics | Number of seconds | 10 | This is the delay between any two consecutive photos |
| Display | 0=off, 1=on | 0 | The default is to keep the display off as much as possible to preserve batteries during the flight. Turning the screen off is kind of tricky, and requires you to press ALT twice after launching the intervalometer. The script will tell you what to do and when, just follow the instructions on the screen. Leave the screen on if you want to check what the intervalometer is doing before a real flight |
| Prefocus | 0=off, 1=on | 1 | This only works in mode 1 (photo intervalometer). If you use it in mode 0 (videos + photos), it won't have any effect. When turned on (1), the script will try to pre-focus once at the beginning, then lock the focus. If the script can't acquire a valid focus after 5 attempts, it will error out and you will have to start over. This is especially useful when the camera is pointing at a low contrast area where the autofocus usually struggles, such as the sky or a large mass of clouds. On the other hand, the temperature and pressure changes might affect the optics and the surface focus might no longer be valid at high altitudes. I haven't really tested it on a real flight (yet) |
To launch the intervalometer (or any script in CHDK), enter the ALT mode, then press the shutter. To abort a running script, press the shutter again.
These are the recommended settings if you want to use the intervalometer for high altitude balloon photography:
- CHDK menu:
- Take RAW images: off (unless you have a huge flash card)
- Canon menu:
- Picture review: off (this will save power)
- IS Mode: shoot only (this will save power, too)
The Trackuino intervalometer is largely based on CHDK's Accurate intervalometer with power saving and pre-focus and the Spacebits team's intervalometer. Most of the code is actually taken from them, so If the trackuino intervalometer doesn't work for you, make sure you check these out!
This script has been tested on an A570IS camera. If you want to hack into it to try and make it work on different cameras or add functionality, here is some information:
Videos are taken using the "VIDEO_STD" setting (640x480 @ 30fps + mono audio @ 11025 Hz). Other options are "VIDEO_SPEED" (for faster framerate) and "VIDEO_COMPACT" (for lower resolution).
Photos are taken in "Kids and pets" scene mode regardless of the actual dial mode. I found this to be the most appropriate mode to counter the blur due to the payload spinning all the time. In this mode, the camera will favor a fast shutter speed at the expense of a larger aperture (which might cause some optical aberration), while keeping the ISO at a reasonably low noise level. You can try and experiment with different scene modes.
If you want to see what modes are available on your camera, run the SETMODE.LUA script (under the CHDK/SCRIPTS/TEST directory in your SD). It will leave a log file "setmode.log" at the root of the SD card with the list of available modes:
a570 101a CHDK 0.9.9-1200 Jun 5 2011 12:45:41 vxworks 0x314c
START | AUTO 1 32768 STL
TRY AUTO 1 | AUTO 1 32768 STL 290ms OK
TRY P 2 | P 2 32772 STL 360ms OK
TRY TV 3 | TV 3 32771 STL 410ms OK
TRY AV 4 | AV 4 32770 STL 410ms OK
TRY M 5 | M 5 32769 STL 530ms OK
TRY PORTRAIT 6 | PORTRAIT 6 32781 STL 430ms OK
TRY LANDSCAPE 8 | LANDSCAPE 8 32780 STL 420ms OK
TRY VIDEO_STD 9 | VIDEO_STD 9 2597 VID 630ms OK
TRY VIDEO_SPEED 10 | VIDEO_SPEED 10 2598 VID 470ms OK
TRY VIDEO_COMPACT 11 | VIDEO_COMPACT 11 2599 VID 610ms OK
TRY STITCH 15 | STITCH 15 33290 STL 800ms OK
TRY SCN_UNDERWATER 17 | SCN_UNDERWATER 17 16406 STL 730ms OK
TRY SCN_SNOW 22 | SCN_SNOW 22 16403 STL 470ms OK
TRY SCN_BEACH 23 | SCN_BEACH 23 16404 STL 470ms OK
TRY SCN_FIREWORK 24 | SCN_FIREWORK 24 16405 STL 690ms OK
TRY SCN_AQUARIUM 28 | SCN_AQUARIUM 28 16407 STL 390ms OK
TRY SCN_NIGHT_SCENE 30 | SCN_NIGHT_SCENE 30 16398 STL 480ms OK
TRY INDOOR 34 | INDOOR 34 32785 STL 440ms OK
TRY KIDS_PETS 35 | KIDS_PETS 35 32784 STL 460ms OK
TRY NIGHT_SNAPSHOT 36 | NIGHT_SNAPSHOT 36 32779 STL 440ms OK
TRY SCN_FOLIAGE 38 | SCN_FOLIAGE 38 16402 STL 400ms OK
TRY AUTO 1 | AUTO 1 32768 STL 400ms OK
- Interrupting the script while the camera is recording video will leave it stuck at recording until you shut it down.
- List of CHDK's specific functions available to Lua scripts
- Keeping the display off can be especially tricky and camera-dependent. Here is a thread on the issue.
- Accurate intervalometer with power saving and pre-focus
- PropertyCases, these are parameters that can be read or tweaked programatically.
- CHDK's Lua reference, with usage examples for some of the core CHDK functions (shooting manually, reading properties portably, etc.)