Looking for a way to connect an additional display to your Mac, but you’ve already used up the single video-out port most ship with? Air Display ($19.99, Mac App Store) can turn a second Mac computer into an additional display, so you can use your MacBook as a spare screen for your iMac, or vice versa.
Air Display for Mac is the OS X version of Avatron’s iOS application for iPad, iPhone and iPod touch devices. Like the iOS app before it, it lets the host Mac connect to secondary devices via local Wi-Fi in order to use them as additional displays. No wires or cables are required, and the only setup you need to do is install an app on both host and supporting machines.
What It Can Do
If you have experience with Air Display for iOS on the iPad or iPhone, you might be surprised when checking out the Mac version. First, there’s the cost ($10 more than the iOS app); $20 may seem like a steep price to pay for an app this simple, but once you use it, you’ll realize there’s plenty of justification for that price increase. You get much more screen real estate using a second Mac over an iPad, obviously, but also, the performance is much better than when using Air Display on the iPad. It probably comes down to available system resources (which leaves me eager to find out how iPad 2 handles Air Display), but it makes such a big difference that even at $20, Air Display feels like a steal.
Air Display for the Mac is smooth. That’s not to say you still won’t get some stutter when you drag and rearrange windows; you will. But the app seems to recognize when it needs to skip frames very well, so even this doesn’t feel like undue lag or hinder usability at all. Once your windows are in place, cursor movement is absolutely crisp, and your wirelessly-connected Macs can even handle video playback pretty well. A YouTube video playing in its original aspect ratio in both 360p and 720p played back with perfect audio sync and very few hiccups on my Air Display-connected, 2009 13-inch MacBook Pro. Using full screen reduced the quality of the experience considerably, but it still performed as well, if not better than my old G4 12-inch Powerbook playing the same videos itself.
Like on iOS, reconnecting an Air Display computer acting as a monitor will restore your window configuration so that you only have to set up your work station once if you get it just right the first time. You can also choose to have your computer automatically connect to Air Display when you launch the app. Air Display also offers both a scaled window and full-screen mode, so you can choose to both use your spare computer as an extra display and still access its own OS, files and applications. Finally, you can even connect via Ethernet if you don’t have access to a Wi-Fi network.
What It Can’t Do
Air Display isn’t a remote desktop app, so you can’t share files between two computers using it. And while it does work using a Windows computer as the host, and a Mac as the secondary monitor, it doesn’t work the other way around, which is too bad, because I’ve got tons of worthless Windows laptops gathering dust with great screens that would do much better showing off OS X.
The app also unfortunately requires OS X 10.6.6 or later, which means that it won’t be very useful to those with older Mac hardware. I was really hoping to take advantage of the app to put my Powerbook back into service as a second screen, but since PPC support ended with Leopard, it’s not happening.
People who often take screenshots should also note that you can’t capture the screen, windows, or a section of the screen from an Air Display-connected Mac with the built-in OS X screenshot tool, though it does work with Skitch and other third-party apps.
Who It’s For
If you have two or more Macs, you should definitely get this app. Even though I have two additional hardware displays connected to my iMac, there are still times when a fourth screen can come in handy, and I’m sure other multi-monitor enthusiasts out there will agree. Air Display is also great for people who use a Mac notebook as their primary computer and who spend a lot of time working from other Mac-equipped offices, since it means you can easily make use of those computers as secondary displays while using your own system settings, apps and files.
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