Move photos from old iPhone 4

(I)

Connect old iPhone to computer > Go to This PC or Computer > Find your iPhone and open it > Go to Internal Storage > DCIM > Click the folder and you will see the pictures > Copy them to computer.

(II)

Connect your iPhone to the computer using a USB cable. Go to your photo folder on your phone and make sure that you select photos on your iPhone in the camera roll. Start the transfer process of pictures from phone to Windows 7, 8 , or 10 by using the export button

(III)

1. Turn your phone on and unlock it. Your PC can't find the device if the device is locked.
2. On your PC, select the Start button and then select Photos to open the Photos app.
3. Select Import > From a USB device, then follow the instructions.

1) iTunes

2) Apparently an iPhone can be recognised as a read only removable storage (like an SD card) when plugged in to a PC