This tutorial will teach you how to create a burnable ISO image from DVD on Mac OS X (Snow Leopard included).
Step 1 Launch DVD Backup for Mac
Free download DVD Backup for Mac here: http://www.aimersoft-mac.com/dvd-backup-mac.html
To install it, simply mount the .dmg archive by double-clicking it, and copy the application to your applications folder (or wherever you want).
Step 2 Insert DVD Disc
DVD Discs supported: DVD–5 and DVD–9; DVD-R, DVD+R, DVD-RW, DVD+RW, DVD+R DL, DVD-R DL, DVD-RAM.
Step 3 Select Output Format as ISO

Step 4 More Settings
Type the DVD name for the new ISO file, and choose the location where you want to save it. Also, this DVD Backup program offers you 3 copy options: Main Movie Copy, Customized Copy or Full Copy.
Step 5 Start Creating ISO Image
After finishing all the above steps, the software begins creating ISO image.
Now, you can enjoy the movies on your computer or share with others. In the future, you don't need to worry about how to save the DVD discs' life even if they are terminally unuabsle. And you don't need to rip the DVD's on your Apple Mac in order to back up them.
Original article: How to Create ISO Image to Backup DVD on Mac ?