This is the cover page of the Step-by-Step Setup Guide for Server Mode on Apple iOS devices such as the iPad. The wireless file transmitter is the thing that looks like a motor drive mounted to the bottom of the EOS 7D.
Canon recently published a series of step-by-step guides on how to set-up their wireless file transmitters for EOS DSLRs. The guides are available for free download on Canon's Digital Learning Center . If you're wondering why I would mention something that benefits such a small subset of Shutterfinger's readership, it's because I wrote every one of them and, even if I do say so myself, I did a good job on what was a challenging project.
For those who don't know, a wireless file transmitter (WFT for short) enables a camera to connect with a WiFi computer network. You can then use a computer to control the camera remotely, either through a standard web browser or via Canon's EOS Utility application. You can also set up the WFT as an FTP server, in which case it will wireless copy or transfer image files from the camera to a folder on a remote computer. There's even a linked shooting mode that lets you set up one camera as the "master" and the rest as "slaves" (a terminology I'm not particularly fond of). Triggering the master will trigger the slaves, with or without any delays you care to program into them.
Sound complicated? Now consider the fact that how you set things up also depends on whether you're using a Windows PC or a Mac. It should come as no news that PCs are generally more difficult to set-up than Macs. If you're using a Windows PC the setup process further depends on whether you're using Windows XP, Vista, or 7. And let's not forget that there are two different ways to set up a wireless computer network: ad hoc or infrastructure.
Also keep in mind that the network and computer setup steps happen separately from setting up the WFT itself, which involves scrolling through a long series of menu screens on the back of your camera, twirling the Main Dial, and pressing the Set Button. If all that wasn't complicated enough, how about this: All it takes is one missplaced digit or checkmark along the way and your setup won't work.
Here's an example of what you might see if you were using a server mode setup. The white box in the center is the focusing point. You can probably figure out the rest of the controls simply by looking at the buttons and icons.
The good news is that if you do manage to get everything set up correctly, it's tons of fun to be able to mount your camera + WFT on a tripod and wirelessly control camera settings such as focus, exposure, ISO, and white balance from a remote computer. If your computer is attached to a large, well-calibrated monitor, it's like having a high-definition flat-panel TV as your LCD display. Any photos you take can be saved to your camera, your computer, or both.
Before you get too excited (or too disappointed that your camera system doesn't offer a WFT) here's one last factor to keep in mind: WFTs are pricey ($600-800) and only fit a specific model of camera. I would get one only if I really needed one, and even then I'd want to be sure I had the necessary skills, or knew someone else who had the skills, to set up a computer network. In the meantime, there's no harm in waiting for some enterprising company (Apple perhaps?) to design a camera that makes wireless connectivity so easy that even a photographer can do it.