This post is a case of putting the information up here as an aide memoir. I had trouble with this. Not because it’s difficult but because once done it’s easy to forget how you did it months later when a change of SD card prompts a re-install. This example is for the Canon S95 other ‘powershot’ cameras should be similar. I got this to work on the Canon Ixus 7 too.
Custom cable. The cable is a hacked mini USB one with the A end cut off and replaced by a Futaba type connector. Inside the USB end only the red and black wires are required. There are some variants about and the ones I have used successfully are the ones with a red and a black wire in them. Join the red wire to the red on a Futaba lead and the black USB wire to the white Futaba (signal) line. That’s it. If the soldering iron is not your thing a professionally made one is available from Gentles Ltd.CHDK . Provided the camera can support a build of CHDK the cable can be used to trip the shutter remotely by clickPan or radio control. This is the bit I got stuck on. With CHDK loaded on the camera ( I used David Mitchell’s excellent ‘Stick’ to do this) the setting for remote control is easy to find, select CHDK settings:
I found ‘One push’ and ‘Normal’ to work fine. At this point it is tempting to plug in the cable and see what happens, I’ll tell you: nothing happens unless the cable is live. The shutter is triggered via the cable but the camera may not achieve AF/AE operation before the signal is passed. To get more responsive control a script is required. The script in question is called REMOTE.BAS and it’s hidden:
Navigate to the ‘Exam’ directory…
Operation of the USB shutter release. It’s worth remembering the live USB connection disables the camera controls.
The sequence is:
- With the camera in the rig and the power off connect the cable.
- Boot the camera (CHDK should announce is presence with the splash screen).
- Open the lens out in shooting mode (usually by pressing the shutter button).
- Put CHDK in ALT mode with the assigned button (varies, may be print/video/review button).
- Start the script by pressing the shutter button (the ‘started’ message should appear).
- Power up the rig and the camera will shoot on signal to the USB from the controller (clickPan/ RC and my favourite clickPanPro).
Bill – you’ve made a small mistake there. CHDK (and SDM) run in one of two states, normal and ‘Alt’. ‘Alt’ mode lets you adjust CHDK/SDM settings (such as the remote settings of a script to run) and run a script by clicking the shutter button. In normal mode, CHDK is still active (with whatever settings you set) and clicking the shutter will take a picture.
Now if the camera is Alt mode, it won’t do anything unless a script is running. So if you want to trigger the shutter in Alt mode via the USB port you have to run a script that checks the USB port for power and clicks the shutter if so. That’s the remote.bas script you mention. But, and it’s a very important but, if the camera is in normal mode then a pulse on the USB port will trigger the shutter – you don’t need to be running a script.
There is a good reason for doing it your way though – if a script is running it can not only click the shutter when there’s a USB pulse, but it can also adjust the ISO, focus, aperture and shutter speed to optimise the picture. That’s what the kap_uav.lua script writen by WaterWingz does. Although it can run as a simple AUtoKap script, you can also make it wait for a usb pulse before clicking the shutter.
Triggering the camera without the script might be useful. I shall investigate this as the S95 can be slow to react and miss shots under remote.bas even with a generous interval set on clickPan Pro.