Auto Brightness Slider for Edge 1050?

I find that the auto brightness on the 1050 isn't quite bright enough with my 55-year old eyes and darker cycling glasses.  I remember finding a slider somewhere that allowed you to adjust the brightness gain even in auto-brightness mode for one of my previous Garmin Edge computers.  I can't find this anywhere for the 1050 (or my 1040, which I still have around until it sells on eBay), but I remember having a hard time finding it for some reason.  Anyone know if this is possible with the 1050?  I don't want to turn auto brightness off.