No Need for Auto-Dim Settings on the BlackBerry Z10
The setting for Auto Dim isn't present on the Z10 because it's fully baked in

If you read our recent BlackBerry 10 Help article outlining Ten Tips to Extend the Battery Life of your BlackBerry Z10, you may have noticed Adam mention that the Automatically Dim Backlight setting found in BlackBerry OS devices was missing on the BlackBerry Z10.

We weren't sure if this was a missing option on the BlackBerry Z10 that would be coming later or if there was another reason to explain its absence in the jump from BB7 to BB10, so we reached out to BlackBerry for the details.  

The product guys enlightened us with their response:

We spent a lot of time developing the "GLO" algorithm ("Garber Light Optimization", after the engineer who developed it) to automatically adjust the display backlight setting to provide the user with the same perceived brightness regardless of the ambient illumination level. The slider moves that auto-dimming curve up and down to match a user's preference. 

Pretty cool, right? It's all about the GLO algorithm. As for those looking to save battery life on the Z10, the product guys also reiterated what we said - if you want to save juice, reduce the brightness of your display.