As Francisco said, you may want to mount the device instead of using PTP. My advice is to get a USB card reader and not try to mount the camera; that's what I do. Most cameras at that level or above can be switched from PTP to USB Mass Storage mode. Change to mass storage and then you'll get umass/scsibus/sd0 and it's just like an external disk. I have not messed with PTP and gphoto2 in a long time - the USB interface part may be not portable enough.
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