Avatron's new Air Stylus (US$19.99) app transforms third generation or newer iPads into pressure-sensitive drawing surfaces compatible with desktop graphic design apps.
The app is an outgrowth of Avatron's Air Display app. Air Display extends your computer's desktop to your iPad or iPhone to provide an extra screen. Air Stylus layers pressure-sensitive drawing on top of that display functionality. Not only can you view items on the secondary screen, you can draw on them too and in a meaningful way. Think of a Wacom tablet that you can place in your lap and draw onto, but one that shows the image you're drawing and not just a blank surface.
There were a few gotchas. First, for an app to work with Air Stylus, it must be pressure-ready. On the Mac, that means working with apps like Acorn, Pixelmator, Manga Studio 5, Art Range, Intensify Pro, Mischief, and Photoshop Elements. Acorn is a terrific app that I happened to have on my system available for testing. Avatron has posted Photoshop how-to for those who wish to follow through with frame buffers and GPU settings, but don't think that the app will produce out-of-the-box pressure input for all drawing apps.
Second, there is lag. Although a slight lag usually isn't a problem with Air Display -- especially when you're using the extra screen space for something not time critical such as Twitter -- when drawing, even a half-second of lag can really throw a wrench in things. This does not appear to be a problem for the artists highlighted in Avatron's shiny video and there were times in testing when reaction time was excellent, but at others I experienced a noticeable, albeit slight lag between drawing and the app responding. It was irritating.
Third, there is sensitivity. I encountered difficulty when trying to consistently draw a line that changed pressure. You can see a subset of my attempts recorded here. The video shows the Reflector capture session of my iPad Air as I used both the brush and pencil tools. Eventually, I learned to put a bit of pressure onto the stylus to get the sensitivity going and then back off or press harder. I am never going to be a calligrapher and the process of learning to draw with pressure using the stylus was harder than I expected.
I tested Air Stylus using a Wacom stylus, a Pogo Connect, and a cheap no-pressure stylus from the dollar store. The app worked well with all three. For pressure testing, I stuck with the Wacom as it was the only one that worked for those tests (Avatron plans to update its support for Pogo Connect soon).
While I personally found Air Stylus difficult to use gracefully, I did love how well I could zoom and pan to focus my drawing space exactly where and how I wanted it. I suspect many of my difficulties stem from my ham handed lack of any sophisticated drawing abilities.
I also liked how the desktop client offered to save my extra window state until I was ready to pick up and draw again. Unlike other screen extension apps, Air Stylus didn't revert my window configuration until I told it to. That's a great feature.
At US$20, Air Stylus isn't going to be an impulse buy for most people -- especially when you take the stylus and drawing app prerequisites into account. However, if you're a serious artist and have mad pressure-sensitive skills, I think the app has the potential to really grab you.
Be aware that the app is new and growing. Reaction on the App Store has been mixed. From an admittedly small sample, it's currently middling in ratings and has at least two very unhappy customers. I was more apparently impressed then they were, and I look forward to seeing how this app evolves.