With Photoshop CS5, Adobe quietly–well I say quietly since I don’t remember hearing about it–introduced a new API that allows Photoshop to communicate directly with tablets like Apple’s iPad. In conjunction with this, they also introduced an iOS app called Adobe Nav, which provides easy touch control over Photoshop from your iPad.

Setup for Nav is quite painless. On your desktop, in Photoshop, you’ll need to enable remote connections and assign a password. This is done through the aptly named Remove Connections entry in the edit menu.

The iPad side of things is likewise staggeringly easy. When you fire up Nav for the first time, you will be prompted to connect to a computer (if not, tap the PS icon in the lower right corner). Simply tell it what your computers hostname or IP is–both of which are listed in the Remote Connections dialog box when you turned it on–and type in the password you set for your computer.

When Adobe Nav is setup, and connected to your computer, you’ll be greeted by the home screen. When the connection is established, the PS icon in the lower right corner will be blue; when there is no connection, it will be gray.

The home screen provides easy access to 16 customizable toolbar buttons, the color picker, a zoom 100% button and the ability to cycle though the display modes. What’s conspicuously absent in the whole thing is the ability to zoom back to see the whole image in a single click.

The tool bar buttons can be customized by taping the edit button in the lower left corner. Adobe says there can be up to 16 custom tool bar configurations, I haven’t found the need to make that many yet. The buttons themselves can be either toolbar buttons, or actions, which can be handy if you’re a big action user.

The second major functionality is that Nav can be used to manage your open documents. Tapping the 4-square gird at the bottom center switches nav to the document manager.

In document management mode, each open document is shown as a thumbnail. Double tapping the thumbnail brings up the document’s info including file name, file size, dimensions, height and width at the defined PPI, and the color depth mode. Tapping the + in the black square allows you to create a new image, or upload one of the images from your iPad to work on.

While my workflow isn’t conducive to uploading images from my iPad, the functionality is there none the less.

That said, Adobe Nav has a number of significant hurdles to overcome, though almost none of them are Adobe’s fault. But let me start with the one that is; the buttons in the center of the toolbar are far too easy to accidentally hit with the palm of your hand if you’re wresting it on a flat or slightly inclined iPad. The fix is easy enough, Adobe just needs to add the ability to shift the toolbar from the bottom to the top of the screen as a user option.

The real problem is one of ergonomics and usability, and unfortunately this is a side effect of a touch screen device and not something Adobe can really fix.

The first problem is that there’s no easy way to reliably hit the buttons without looking at your iPad. This is the simple reality of a touch screen device, and it’s extraordinary difficult problem to address. As a result you have to look at the iPad to see what you’re hitting when you want to switch tools.

The problem is exacerbated a good deal by the inability for Adobe Nav to send modifier keys to Photoshop (i..e shift, ctrl, alt, option, cmd, etc.). As a result, you can’t just orient your hand once and keep it there; you need to move back to the keyboard while you’re working, at least if you use the modifiers to alter the behavior of your tools in Photoshop.

The continual need to look at Nav is also a problem, as it’s extraordinarily difficult to place the iPad somewhere that is both in your field of view and not obscuring your display. This results in a tendency for you to have to make large shifts in view, often requiring turning your neck. Needless to say having to turn your head and refocus twice (once to the ipad and then again back on the screen) dramatically reduced the speed at which you can work.

One thing Adobe did get right is the buttons are large and easy to hit. They also use the same icons, only bigger, that the tools in Photoshop use, so they’re quick to identify if you’re use to looking at the icons.

As for the $2 question everybody is asking by now is, is Adobe Nav worth the $1.99 for the app. Quite honestly I don’t think it is. For starters, Photoshop, without which the app is completely useless, is a pretty hefty investment, making the $2 feel more like an insult than anything else. On top of that, while it seems at first blush to be really cool, the novelty wore off quickly when I was working less than half as fast as usual, and had to keep looking at my iPad to see what I was doing.

Adobe Nav may be more handy to some than I think it is for me. Maybe I’m just too old of a dog to teach a new trick to, maybe it’s just the way I’m setup to work. In any event, in my opinion at $2 it’s just not worth it.