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Public Lab Research note

CHDK Scripting

by nicholas | December 05, 2013 20:38 05 Dec 20:38 | #9858 | #9858

The last several time I've been balloon/kite mapping I've used the standard Cannon A495 which so many Public Labbers love. In reality I borrowed this camera and used the SD card which came with and which uses the CHDK timer script. All of this was pre-installed for me so I never really had a full grasp on how to install and use the CHDK stuff myself. But no more!

In preparation for the Public Mapping Mission course and the mapping of Newtown Creek, I went ahead and explored some of the ins and outs of the CHDK. Below are my notes. The notes are a bit long but the process is actually pretty easy and quick. There may be some variation based on computer and camera differences but this is what I was able to get working. Good luck!!!

System Notes:

Camera: Cannon Powershot SX160 IS Computer: Mac OSX 10.9 (Mavericks) SD Card: SanDisk 8GB SDHC 1 30MB/s Script: chdk-timer.txt (sent to me by Liz Barry)

Step 1: Download STICK

This is an application that will automatically find your camera's firmware version, download the firmware and install CHDK. This application basically does everything for you!

Step 2: Run

This might be a funny step for some. The downloaded zip file has lots of file depending on which computer and operating system you are using. Since I am using Mac OSX 10.9, what I needed to do is open Terminal (/Application/Utilities/Terminal), change directories into the stick folder (cd ~/Downloads/stick/), and run the file (bash You man need to install Java which is noted on the STICK web page. Furthermore, double clicking the file might work. When I tried this it launched Xcode which I didnt want to deal with.

Program Interface:


Step 3: Take sample photo

Insert the SD card into the camera and take a photo. Any photo will do. Eject the SD card from the camera and insert it into the computer.

Step 4: Follow Directions in the Stick application.

First, drag the photo that you just took off of the SD card an drop it onto the STICK application. This will then get the firmware version of you camera from information on the photo. Click next several times to walk through the STICK application.

Step 5: Upload custom script

At this point, STICK has installed a bunch of files onto the SD card. CHDK is now installed and ready to go. What we want to do next is to install our custom script. This script will take a photo at a regular interval. Take the text file and drop it onto the SD card in the scripts folder (/CHDK/Scripts).

Step 6: Lock the SD card

Now that the script is on the SD card, you can eject the card and insert it into the camera. IMPORTANT Be sure to lock the SD card. This tells the camera to use CHDK and not to act like a 'normal' SD card.

Step 7: Selecting the script

The hard part is over! You've successful install CHDK onto your SD card and uploaded a script to the camera! Now you need to activate that script. When the camera turns on, push the 'FUNC/SET' button. This takes you into the CHDK mode. From there, navigate to "Load Script from File". This will show you all of the scripts installed. Select the one you uploaded (chdk-timer.txt). There should also be a section at the bottom of this menu that says 'Interval Shooting Non-stop'. I usually set the interval to 10seconds.

Step 8: Start/Stop the script

This is the step that always throws me off. You must start the script by pushing the 'take photo' button. Once you've pushed this the first time, the script should activate and start taking pictures automatically!!!!! If you want to stop this, just push the 'take photo' button again.

Congratulations!!!! You've successfully installed a script to your camera! Now you're ready for some balloon/kite mapping!

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Congrats Nicholas. That effort getting familiar with CHDK can greatly improve your aerial photos. Two notes on your procedure:

  1. Your Powershot was released after 2010 so you can use an SD card larger than 4 GB and run CHDK from it. For older Powershots released in 2010 or before, SD cards larger than 4GB must be partitioned to auto-run CHDK as you do. This is not hard to do, and STICK will do it for you, but you must regularly switch partitions (make one or the other "partition 1") when copying photos to a computer vs.using the card in the camera. It's not too intolerable, but it's something to consider (and in fact it can be pretty intolerable).
  2. The buttons to push to enter CHDK mode differ from camera to camera.

One CHDK feature that can dramatically improve aerial photos is shutter priority to keep shutter speed high. But your SX160 has built in Tv mode so you don't need CHDK for that (don't forget to use Tv!). The SX160 also has manual focus, which is another important aerial photo plus (set it to near infinity). The SX160 also has image stabilization which you probably want to turn off while flying, but experiments are warranted.

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Thanks for further information and some clarification. Looking forward to using the SX160 though feels a bit heavy compared to the A495. Will report back how it goes. Other additions to this are certainly welcome!!

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