Monthly Archives: December 2015

Duet Display- Make the iPad a secondary display for your Mac or PC

 Even though I have a 15 inch MacBook Pro retina display, I often find myself needing more screen real estate when I am using my MacBook  while traveling. As a specific use case, I feel that academic radiologists can benefit from having an additional display especially when they are checking trainee reports on imaging studies or monitoring scans remotely. Or having an excel spreadsheet on a separate screen while going through a series of research studies. There are a number of iOS apps (with companion apps on the Mac) that let you use the iPad as a secondary display. However, many of these apps are pretty slow as they communicate using Wi-Fi which is not fast enough for what I would like to use the secondary display for.

I recently came across an app called Duet Display which works in conjunction with a companion Mac app and provides a wired connection using the lightning cable between the Mac and the iPad. It costs $15 on the iOS App Store and has been developed by ex-Apple employees.
This app provides a high-speed connection between the MacBook and the iPad and unlike its competitors, it works using a wired connection created between the two using the lightning cable. The combination of a custom driver and a wired connection means the speed of the connection is extremely fast. The app developers claim up to 60 frames per second and I personally did not have any trouble switching between the two monitors and also dragging windows around on the secondary display. There are two display options for the iPad display – one with a frame rate of 30 fps and the second at 60 fps, and if you have a retina display mac like me, you can also choose between retina and normal display modes via the app’s menu bar interface.
The only downside to using Duet Display that I could find is its relatively heavy usage of CPU capacity when running it using the discrete graphics as recommended. This can mean a battery drain when the MacBook is running on battery power, like in a coffee shop. This is easily remedied by ensuring that you are plugged into a power outlet. The developers have provided an option (via the menu bar) to use integrated graphics for energy savings, but this choice comes  at the cost of responsiveness. Apart from this minor drawback, this is a fantastic app for $15 that provides a fast and very responsive extra display for your Mac and is a boon when I travel with my Mac and iPad as my only display options. I now use this as my app of choice to connect my Mac to my iPad Air 2 and highly recommend this to anybody who wants to use an additional display for the MacBook. And all you Windows afficionados might be interested to know that I have friends who have used this app to use the ipad as a secondary display on their Windows laptops.