Clarification on brightness setting for calibration

[Sancurtis]

Hello - I am using an iMac and using the datacolor spyder pro for calibration.  The instructions say to match your test prints to the brightness of your monitor and adjust accordingly before starting the calibration process.  Is this adjustment made using the brightness control on the keyboard or the display setting in preferences?  Thank you

[Damien Symonds]

Oh, that's a great question.

Generally I find the keyboard doesn't give enough precision, so I'd recommend you use the slider in preferences.