When N told me that she couldn’t think of a suitable present for my birthday, she suggested I buy something myself and she’d give me the money to pay for it, so I ordered a Griffin PowerMate. I read about the PowerMate back when I ordered my iMac some 17 months ago – I’d considered buying one at that time but, for a reason I can’t remember, never did.

On opening the packaging the first thing I noticed was how weighty it felt – it’s not exceptionally heavy, but it does feel it when compared to, say, my Mighty Mouse. It was also bigger than I expected – I’m not sure why, but I just imagined it to be smaller than it is. Using a ruler (duh) I can tell you that the base is about 2¼ inches across while the top is about 1¾ … that’s 5½ and 4¼ centimetres for those of you watching in black and white.

After plugging the PowerMate into a spare USB port in my keyboard and installing the software (which forced me to reboot – shock horror!) I was ready to start twiddling my knob. It has several actions: rotate right/clockwise or left/anti-clockwise; click (press down); long click (press down and hold); and click and rotate right or left (press down and hold whilst turning).

At first I had a bit of trouble clicking, i.e. pressing downwards on the top – this was purely a crip problem: it was my spazzy hand that was at fault, not the PowerMate. I found a suitable way of doing it after a bit of practise and now it’s almost second nature.

Whilst in “global” mode, i.e. when the front-most application hasn’t been configured to work with the PowerMate, turning it clockwise or anti-clockwise turns the system volume up or down; clicking does nothing whilst long clicking (i.e. clicking and holding for a specified time) ejects the CD/DVD drive. Turning whilst clicked also does nothing. So, a venture into the preferences is called for:

The layout is simply and, after a quick play around, it’s easy to configure the PowerMate for use with any application. I wanted to set it up so I can zoom in or out in Photoshop: I clicked on “Add Setting…” and a file dialog appeared: from this I selected the application I wanted to use, i.e. Adobe Photoshop CS. Then I selected which action to configure, i.e. rotate right, and then what to do when I perform that action, e.g. send a key-press, and finally which key-press to send, e.g. Command and ‘=’ (which is the keyboard shortcut to zoom in). I repeated this for rotate left (Command + ‘-‘, i.e. zoom out) and “click” (Command + 0, i.e. fit on screen). And that was it – simple.

It’s easy to turn the PowerMate but at the same time it feels, erm, weighty … that is while it’s easy to turn, it’s also easy to control and not too light. The ability to alter the sensitivity is great, too, as sometimes you want it do much in a short rotation, e.g. for scrolling up or down the page Safari, but sometimes you want a bit more control, e.g. for altering the brush size in Photoshop.

The PowerMate is lit from beneath by an electric blue LED which gets brighter or dimmer as the system volume is turned up or down. It can also be set to pulse continually or just while the computer is asleep – the rate of pulse is also configurable.

All in all this is a pretty handy addition to my growing collection of add-ons for my iMac and I can see myself setting it up for some function or other in most of my applications.