I have an iMac 20" mid-2007 and an external 23.6" 16:9 aspect display, I would like to mirror displays keeping a 16:9 aspect on the external display, eventually stretching the image of the built-in 8:5 aspect display.

Is it possible?


2 Answers 2


It is not possible. Apple explains well what happens when you mirror displays:


"Your Mac will attempt to match the closest resolution between the primary (or built-in) and secondary displays. The usable resolution is the closest matching resolution for both primary and secondary display. If you choose a resolution that is not supported on both displays, the resolution will return to the closest matching resolution."

What are you doing that your only choice is to mirror the displays?



  • Hi Dave, I had to record both my desktop and the iSight stream, project guidelines required 16/9 aspect desktops, and I was not too confortable by recording myself watching beside the webcam lens :) Thank you for your answer Jun 16, 2013 at 19:01

AFAIK Apple will not distort a display. Instead it will preserve square pixels by letter-boxing or pillar-boxing one or both of the displays as necessary.

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