It is becoming increasingly rare, still from time to time I get a DVD or CDROM as installation media. To create an iso-image from optical media under Ubuntu, run:
readom dev=device -f file.iso # e.g.: readom dev=/dev/disk/by-label/your-media-label -f /place/to/store/the/image.iso
The program readom (read optical media) a is available from the package wodim
apt-get install wodim
readom serves for me better than dd as it has build-in error checking and shows progress out-of-the-box.