Require adminstrator password at turn on

I have OS 10.8.5 on my IMac. For security I want the computer to require an adminstrator password when I turn on the machine, but not afterward, like I did in the earlier OS. In the "Security Privacy" section of the Systems Preferences it seems to only provide for this requirement AFTER the computer is on but when there has been no activity for a period of time . Thanks in advance for any help.