How to boot to a different Operating System on a Mac using Startup Disk

Here we have a iMac setup with 4 Operating Systems using the Partition option in Disk Utility. This video shows you how to use the Startup Disc function inside system preferences to boot to the respective operating system you require. If your wondering why your machine seems to take ages too boot just check that the operating system you require is highlighted in the Startup disk and then reboot.