If after connecting your iPhone via USB you are experiencing the following:
"Cannot see any photos in the DCIM folder of my iphone 4 when connected to my PC"
This is typically due to the iPhone or iPad going into the screen lock or you plugged in while it's locked by the password.
The security set by iOS prevents the DCIM populating the images.
To fix the problem:
- Unplug the USB
- Unlock the screen
- Plug the USB back into the PC
You should be able to see the images.