One of the popular uses of scripts and automated camera actions these days is to make HDR images (combining several different-exposure images to increase the captured dynamic range far beyond what any camera can do on its own). This used to require some additional and more complex scripting commands, as you can see by studying the HDR Scripts posted here. However, since the Allbest Build was introduced there has been a simpler way where nearly any intervalometer script may be used for this purpose.
All that is required is that your build of CHDK has the "Extra Photo Operations ->" menu with the built in burst bracketing features, and that your camera has a built-in Custom Self-Timer feature.
- 1. Go into your camera's menu (not CHDK's <ALT> menus), and select the "Self-Timer - Custom" feature. Press [SET] to enter the custom timer options menu. Set the "Delay" to 0 (zero) seconds. Set "Shots" to how many bracketed shots that you want for each HDR sequence. (Usually 3 or 5) Press [SET] to exit your custom timer settings. Press [Menu] again to exit your camera's menu options.
- 2. Go into CHDK's "Extra Photo Operations" menu and select "Bracketing in Continuous Mode". Set the bracketing type that you desire for HDR. Usually Tv bracketing is used but some people use Av bracketing. Set your "Bracketing Type" to "+ / -".
- 3. Set your camera into "Custom Timer" shooting mode.
- 4. Run any single-shot intervalometer script.
Each time the script triggers to take a single shot, your custom-timer mode kicks in and takes as many photos as you have set it for. While the CHDK built-in bracketing mode changes the exposure for each shot. This process will repeat for each intervalometer script's single-shot command.
This may seem confusing at first but once you understand what is going on it becomes a simple process to remember. The script is controlling how often to take a bracketed sequence. The camera's custom-timer mode is setting how many bracketing shots to take, and the CHDK bracketing mode sets how much of an EV range and type of bracketing will occur for each shot.
The upside of knowing this is that you no longer need a gazillion little scripts to do each type of bracketing sequence. Only one decent intervalometer script is needed to do all manner of bracketing shots. The bracketed shots are taken at a high-speed so there will be little change between bracketed shots when it comes time to stack them. An intervalometer script may even be turned into an elaborate focus-bracketing script using this method -- a huge bonus for intervalometer macro-photography where you might need an extremely deep depth-of-field to capture the growth of some plant or fungus. The flexibility of knowing this method far surpasses having dedicated scripts for all these purposes, with no need to re-write or tweak some script if you need it to act different than first intended. Just change your built-in CHDK bracketing method and/or the camera's self-timer options instead.
One more bonus: Using the camera's Custom Self-Timer's counted shots with CHDK's Continuous Bracketing you don't even need a script to take single-event HDR or Focus Bracketing shots. You can manually initiate a counted bracketing sequence this way with each shutter press. No need to even run a script, the camera + CHDK will do it all for you. The flexibility of knowing this method becomes limitless.