Sidecar is one of the most prominent new features in macOS Catalina, allowing your iPad to extend or mirror your Mac's display. You can also use it with the Apple Pencil, which also lets you use your iPad as a connected drawing and markup tablet, much like a Wacom or similar accessory.
But Sidecar isn't the first time this sort of feature has been available for the Mac. Apps like Duet Display and Luna Display have been offering this type of functionality for years. Luna Display, in particular, is great for turning your iPad into a second, interactive wireless display for your Mac. You just need the hardware accessory.
Though Sidecar is free with macOS Catalina, are there reasons to choose Luna Display instead? Let's find out.
What are Sidecar and Luna Display?
Sidecar and Luna Display are, at a conceptual level, the same sort of thing: they turn your iPad into an extension or mirror of your Mac's display. Both of them work wirelessly (though you need a dongle to achieve this with Luna Display) or over a wired connection.
Both also allow you to use touch, and it's in this area that Luna is actually the more full-featured product. Luna has been engineered to take advantage of your iPad's large touchscreen and apply its utility to the Mac. While Sidecar also allows for multitouch, and has unique controls of its own, its support for using multitouch functionality with macOS isn't as robust.
It's important to note here that Luna Display isn't just a free iPadOS app with a companion on macOS. It's also a hardware product, and the two really can't be separated. Luna Display works by plugging into your Mac and uses its GPU directly to provide a smooth user experience no-to-very low lag. This is opposed to different software-based second display solutions that trick your Mac's graphics card into thinking that a second display is connected. Luna gets the benefits of graphics acceleration because it works properly with your GPU.
A note about wired connections
Though both Sidecar and Luna Display seem to prefer wireless connections to your Mac, both can be used in a wired configuration. This is achieved by some version of USB-to-USB-C or USB-to-Lightning cable. But there are certain caveats that you need to understand before you plunge on in.
The first limitation of a wired connection applies to both Sidecar and Luna Display. You need to plug your iPad directly into your Mac, rather than indirectly through a dock or hub. This means that you'll need to have at least one USB port open in order to get Sidecar or Luna to work.
The other limitation is one that only applies to Luna Display. Even when using a wired connection, you'll still need to have the Luna Display hardware plugged into your Mac. That means you'll be taking up two of your Mac's ports, though this might not be much of a difficulty depending on how you're using Luna Display and which model of Mac you're using. More on that later.
Sidecar vs Luna Display: The basics
|Header Cell - Column 0||Apple Sidecar||Luna Display|
|Price||Free||$69.99 for hardware component (Luna Display app is free)|
|Supported Macs||2016 Macs and later running at least macOS Catalina 10.15||2011 Macs and later running at least macOS El Capitan 10.11|
|Supported iPads||2015 iPad Pro or newer, 2018 iPad and later, 2019 iPad Air and iPad mini running at least iPadOS 13.1||Any iPad released in or after 2011, running at least iOS 9.1|
If your Mac is running anything older than macOS Catalina, and will do so for the foreseeable future, then Luna Display is your only choice of these two. Sidecar requires macOS Catalina, so you'll need to update to macOS Catalina first if you want to use that feature. Otherwise, Luna's your best bet here.
Even if your Mac runs macOS Catalina, you might still be out of luck for Sidecar. You need to be running a Mac from 2016 or later in order to connect using Sidecar. On the flip side, Luna Display only requires Macs from 2011 or later. Luna also supports iPads going all the way back to the iPad 2 in 2011, while Sidecar needs either any generation of iPad Pro or an iPad, iPad Air, or iPad mini released in 2018 or 2019. If you use some older hardware that still runs well, Luna is a great solution.
Sidecar has two mains strengths over Luna Display: it's built directly into macOS, and, related to that, it's free. If you do have a newer Mac and a newer iPad, it's a very convenient option for using your iPad as a second display, and even as a drawing tablet if you have an Apple Pencil. There's no extra hardware to buy, and no companion apps that you need to install. The functionality is all just there in macOS and iPadOS. For a lot of people, Sidecar is going to be the right solution.
For more advanced users, however, even with newer Macs and iPads running Catalina and iPadOS 13.1, there are reasons to choose Luna over Sidecar.
One of the biggest differences between Sidecar and Luna Display is the hardware they support. Sidecar requires newer Macs and newer iPads. Here's the full list:
- MacBook introduced in 2016 or later
- MacBook Air introduced in 2018 or later
- MacBook Pro introduced in 2016 or later
- Mac mini introduced in 2018 or later
- iMac introduced in late 2015 or later
- iMac Pro introduced in 2017 or later
- Mac Pro introduced in 2019
- 12.9-inch iPad Pro
- 11-inch iPad Pro
- 10.5-inch iPad Pro
- 9.7-inch iPad Pro
- iPad (6th generation or later)
- iPad mini (5th generation)
- iPad Air (3rd generation)
Meanwhile, Luna Display is compatible with hardware that's getting close to a decade old. You need a Mac from at least 2011 running macOS 10.11 El Capitan or later, as well as an iPad 2 or newer (including all models of iPad Pro, iPad Air, and iPad mini) running iOS 9.1 or later.
Extending your Mac
Sidecar and Luna both extend your Mac's desktop environment to a second display. Sidecar is actually fairly strict about keeping the iPad as a second display. Conversley, Luna lets you, if you so choose, use your iPad as your primary display. In fact, once you've set it up with using another external monitor, you could potentially use your iPad as your only display for your Mac.
Third-party apps can add support for Sidecar, including special toolbars and other interface elements that pop up on the bottom of your iPad's screen when you're using an optimized app. These tools can include things like brushes or a color picker in artistic apps, or different pen strokes or styles in a note-taking app, and can let you focus on using your iPad without having to navigate back your Mac's primary display to change tools.
For Luna Display, that story is a little more complicated. The Luna app doesn't have any additional controls, functioning only has a display, albeit one with a little extra capability. The app connects to a companion applet
Luna is developed by the creators of Astropad and Astropad Studio, apps that turn your iPad into a drawing tablet for your Mac. As mentioned previously, Luna Display is a piece of hardware along with an app, and that hardware works (and improves the drawing experience of) Astropad and Astropad Studio. If you're looking to primarily use your iPad as a drawing tablet, you don't even need the Luna Display app. You can just download either Astropad app and use that with the Luna hardware for graphics-accelerated artistic endeavors.
The Astropad apps support pressure sensitivity and tilt from the Apple Pencil, where Luna Display does not. Astropad also features customizable controls for each app, and you can customize every part of your artistic workflow as needed.
The biggest hurdle for perspective Luna Display and Astropad users will be cost. The Luna Display hardware already costs $70, but Astropad Standard is on the App Store for $30, while Astropad Studio is free to download, but then has a $12 a month/$80 a year subscription. If you're a dedicated artist, pro or not, this may be worth it for the overall richer experience Astropad provides, but for more casual or occasional users, it'll be hard to swallow.
Touch and Apple Pencil
Both Sidecar and Luna Display support Apple Pencil out of the gate. It's great for drawing in apps like Affinity Design or Pixelmator Pro, or for writing out notes in GoodNotes or Notability, or making precise edits to photos in Affinity Photo. Sidecar takes advantage of Apple Pencil features like pressure and tilt sensitivity, while Luna Display doesn't, with that functionality available in the company's Astropad apps, as mentioned above.
Where Luna really excels over Sidecar in this are is with multi-touch. As the company says, Luna turns your iPad "into a touch Mac that works over Wi-Fi." Use one finger to click, two fingers to scroll, pinch, and zoom, and more. Touch support in Luna is excellent and turns your Mac into the touchscreen device that many have wanted for years. While Apple Pencil support isn't as full-featured, it's easy to use for precise actions, such as grabbing the edge of a window for resizing, or clicking on a small object like a windows close button. As a pure pointing and navigation device, the Apple Pencil actually works quite well.
When it comes to touch and Sidecar, the results are...less impressive. It's pretty much limited to two-finger scrolling (it's not even inertial, so what you're scrolling through will stop exactly when you do), as well as clicks using the Apple Pencil. For Sidecar, it's apparently second display, art tablet, or nothing.
Luna Display: The hardware issue
As I've mentioned several times before, Luna Display is a hardware product in addition to an app. In fact, it's primarily a hardware product that connects to three apps (Luna Display, Astropad, and Astropad Studio). The hardware is necessary to get features like GPU acceleration, which helps provide a smooth experience, and to use the Luna Display app. It also costs $70. If you really have your heart set on using a touchscreen display with your Mac, you'd be hard-pressed to find something better, so I'd say to go for it.
Also, if you're a professional or even aspiring artist that already uses Astropad or Astropad Studio with your iPad, and you're wondering about switching to Sidecar or getting the Luna Display hardware to speed up your work, I'd say spend the money on the Luna Display for better performance and stick with the system you already know.
Having used Luna Display, it really is an excellent piece of hardware that provides a great wireless second screen experience. And what's more, it comes in two variants. One is USB-C and plugs into Macs with USB-C ports. The other plugs into older Macs via a Mini DisplayPort connector. So if you're like me and have Thunderbolt 2 ports on your MacBook, while you won't be able to use Sidecar, you can use Luna Display.
Which one is right for you?
Assuming you're not already using Luna Display or similar software, the answer to this question is going to really depend on what you want to do with it.
If you want a second display with extended functionality like a touch bar or other controls, and only plan on using your iPad like that when you're at your Mac, then Sidecar is probably the right choice. This is also true if you want to use its app extension functionality for some photo editing or light drawing.
But if you're a digital artist, I'd seriously consider going with Luna Display. As it's primarily a hardware device, the limitations of the Luna app are fairly secondary. The Astropad apps are purpose-built tools for artists that allow them to use their existing iPad to unlock the artistic power of their Mac in a way that Sidecar just doesn't, at least not yet. What's more, apps don't need to update to support Astropad, where to get the most out of Sidecar, they do.
Perhaps more importantly, Astro HQ (the developers of Luna Display and Astropad) is preparing to take Luna and Astropad cross-platform. If you're an iPad user looking for a cross-platform solution, Luna Display isn't ready just yet, but the work is underway. Sidecar, meanwhile, isn't coming to Windows.
Wrapping it all up
Most users are going to be just fine with Sidecar. It's a great way to add a second display to your Mac and expand your iPad's utility. More advanced users, those that want to really bring multi-touch to the Mac or have an artist-focused experience, really should take a look at Luna Display and the Astropad apps.
Sidecar is free with macOS Catalina as long as your Mac and iPad support it. The Luna Display hardware is available directly from Astro HQ for $70.
Let us know if you have any questions about using Sidecar or Luna Display in the comments.
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Joseph Keller is the former Editor in Chief of iMore. An Apple user for almost 20 years, he spends his time learning the ins and outs of iOS and macOS, always finding ways of getting the most out of his iPhone, iPad, Apple Watch, and Mac.