No 'automatic brightness' option with mid-2010 iMac?

[alexjholland]

Hey, I just tried to enable automatic brightness on my 2010 iMac, as I use to both when bright and in the dark, but the option doesn't seem to be there.

I'm running OSX Mavericks.

Was this option ever here? Is it available on my iMac, or was I imagining it?

 

[Intell]

I don't believe that model iMac ever had an ambient light sensor.