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I have a Canon EOS Digital Rebel XTi that I'm using for timelapse photography (see an early effort here).

I'm controlling the camera using gphoto2 on a Raspberry Pi, taking individual frames every few seconds with the following invocation:

gphoto2 --capture-image-and-download --filename /home/pi/captures/#{Time.now.to_i}.jpg --keep

Everything works as expected when I'm running the camera off batteries. However, I wanted to switch to an AC adaptor in order to get longer runs. I ended up buying an aftermarket AC adaptor and trying that.

For manual photography, the AC adaptor works fine. Whenever I connect the camera to the Raspberry Pi over USB, it appears to lock up. gphoto2 no longer works. The camera used to detect correctly, but on AC power gphoto2 hangs at this point:

1.601074 gp_abilities_list_detect_usb(2): Auto-detecting USB cameras...
1.605026 gp_port_usb_find_device_by_class_lib(2): Looking for USB device (class 0x29a, subclass, 0xffffffff, protocol 0xffffffff)...
1.618621 gp_port_usb_find_device_by_class_lib(2): Looking for USB device (class 0x6, subclass, 0x1, protocol 0x1)...
1.618929 gp_port_info_list_get_info  (2): Getting info of entry 2 (7 available)...
1.624518 gp_port_set_timeout         (2): Setting port timeout to 5000 milliseconds.
1.629925 gp_port_set_settings        (2): Setting settings...
1.630163 gp_port_usb_update          (2): gp_port_usb_update(old int=0, conf=-1, alt=-1) port usb:001,003, (new int=0, conf=-1, alt=-1), port usb:001,003
1.630327 gp_abilities_list_detect_usb(2): Auto-detecting USB cameras...
1.634837 gp_port_usb_find_device_by_class_lib(2): Looking for USB device (class 0x29a, subclass, 0xffffffff, protocol 0xffffffff)...
1.643147 gp_port_usb_find_device_by_class_lib(2): Looking for USB device (class 0x6, subclass, 0x1, protocol 0x1)...
1.647675 gp_port_free                (2): Freeing port...
1.649970 gp_port_close               (2): Closing port...
1.650167 gp_port_usb_close [libusb.c:322](0): Invalid parameters: 'port && port->pl->dh' is NULL/FALSE.
1.652945 gp_context_error            (0): Could not detect any camera

So at this point I'm confused. It works on battery, but not on AC, but only if I'm trying to control it over USB. virhilo over on #photogeeks has suggested that it's a problem with the camera being unable to query power information from the aftermarket adaptor.

Anyway, any advice on how to get this setup working would be most appreciated.

1

You probably have a ground loop. Theory is available here. However, this question is off-topic here... Try Googling...

To test this: power off and disconnect the adapter, then take an Ohm-meter and measure the resistance from the powering (input) pins to the powered (output) pins. If you don't see it being open (resistance in the hundreds of mega-Ohm range or above), then this may be the problem.

Try to use a fully isolated adapter (one that uses a transformer).

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