What is the best way to connect a mid 2012 macbook pro to a new ultra wide external monitor?
I'm assuming you're asking about the UltraWide LG monitor range, since this is their registered mark.
The best way would be to use the Mini Display Port (also known as Thunderbolt) on your Mac and Display Port on your monitor (with the correct cable), but you will not be able to use more than 2560 by 1600 (In case you have 15&quot; 2012 MacBook Pro with retina display). Via HDMI, your MacBook is able to output only 1920 by 1080.
Such a compatible monitor should be LG 29WK600-W.