Monday, 14 November 2011

Time-Lapse Script

Starting to develop a script for the camera:

@title Phooka Time Lapse
@param i Interval (seconds)
@default i 15
@param n Counter

rem lots of unanswered questions
rem shooting sequence
rem focus
rem exposure
rem exposure bracketing
rem zoom
rem stopping the camera turn off
rem etc

rem other camera settings

sleep 1000

print "Phooka wait_click ..."

print "Adjusting camera ..."
set_iso 0
rem set_prop p v
rem etc

rem zoom out fully??
set_zoom 0
click "shoot_half"

rem focus on infinity??
set_focus 999999999??

sleep 5000

print "Shot: ", n;
sleep i*1000
goto "shot"


Camera firmware versions and CHDK settings

Canon A560 GM1.00A - hack ok
Canon A570-IS GM1.00E - later

Now I have a ton of new menu parameters to learn about.  The kind of stuff I need to work out includes:

- How to write the time-lapse script? UBASIC? or Lua?
- Any recommendations for settings for exposure controls, or just let the camera do its thing?
- Should I do exposure bracketing for each time lapse?
- Is RAW capture recommended?
- What is RAW buffer caching and do I need it?
- What about focusing? Can this be preset to infinity anywhere? I cannot find such a setting.
- What about zooming?
- Is there any need for a setting to keep the camera on, and lens out, or will this happen if it is taking photographs?
- Is there anything critical to put in the time-lapse script, other to shoot?
- How about preventing any desire to fire flash?
- Anything else I should know?

I suspect there is more to this CHDK stuff than I realize. 

Tuesday, 18 October 2011


The cameras are on order from eBay. The Canan A570 IS (image stabilized) arrived today. Looks in great condition. A weekend project will be to hack the camera using CHDK and check out the time-lapse modes. Then calculate the size of SD card needed for photographs throughout the flight. I have to learn how to boot into this, and set up a script for the time-lapse required:
  • Do I go for a photo every 30s, 1min or longer?
  • How do I preset 'infinite' focus?
  • Must remember to plug the AV socket to turn off LCD display to save battery
  • Will need to order some good Energizer Lithium's nearer flight time
  • What's the best way of protecting against condensation on lens?


For this project I want to avoid any form of on-board computer. I'm using a tiny lite-weight GPS transponder I ordered from China.

Battery life seems incredible. After more than 2 days, both units I am testing still have 75% battery. The Li-Ion batteries are not good at low temperature according to some folks, but with good insulation I think they will be ok, especially for a "short" up and down flight.

My only concern is that one of the units seem less capable at picking up GPS than the other. This is evident by looking at the time stamp returned. I don't want false reporting. More testing 'outside' required.

Another issue to worry about in this type of flight is if the balloon lands in a mobile signal dead zone. To counteract this I will fit two different SIMs for two different mobile networks. Will this be enough to guarantee a signal?

Saturday, 23 April 2011

How simple can it be?

  • GPS SMS responder on O2
  • Backup GPS SMS responder on Orange/T-Mobile
  • NTX2 Beeper/Tracker
  • Down camera Canon A560 7.1 MP
  • Horizontal camera Canon A570 IS 7.1 MP
  • CHDK camera hacks for time lapse
  • Rocket parachute
  • Balloon
  • No on-board computer
  • No tracking during flight
  • Case warm and waterproof
  • Weight TBA

Friday, 15 April 2011

Phooka HAB

This is a blog to document my attempts to build and launch a high altitude balloon. The idea is to make Phooka-1 as simple as possible. Is there any such thing with HAB?