I decided to try Geotagging for myself, to see how easy it really is, and to see how the different types of camera-based receivers and the associated software measure up. This isn't a group test as such, since I've already separately reviewed four of the products that I'll be using. It's more of an overview so you'll have a better understanding of future reviews of GPS units.
For my little expedition I've selected five different receivers. I've got the Sony GPS-CS1 (£80), the ATP PhotoFinder Mini (£92), the Nikon P6000 (£286) which has a built-in GPS receiver, the Nikon D90 DSLR fitted with the optional GP-1 GPS unit (approx £170), and finally a new device, the hot-shoe-mounted Jobo photoGPS, which is currently selling for around £159.
As you might expect from five such diverse gadgets, they all approach the task in a different way. The cheapest unit is the Sony GPS-CS1, launched in 2007, which was one of the first camera GPS units to be available. It is a stand-alone device that is carried clipped onto your camera strap or from your belt using a large plastic karabiner clip.
You have to switch the unit on some minutes before you start shooting your pictures, because it does take a while to lock on to a satellite signal, but then the device keeps a continuous log of its position and the time every few minutes, stored in its internal memory.
When you get home after a day's photography, you simply download your photos, plug the gadget into your computer via USB, the supplied software compares this stored data with the time recoded by your camera in the EXIF data of each photo, and adds the appropriate GPS co-ordinates. Obviously you need to set your camera's date and time accurately for this to work.
In practice the Sony proved to be reliable and reasonably accurate as long as it had an unobstructed view of the sky, but it was easily blocked by nearby tall buildings, and wouldn't work inside a car. It also took the longest to get an initial lock onto the satellite signal, as long as ten minutes when first activated, although turning it off for short periods to conserve its single AA battery revealed that it was much quicker to recover the signal, as long as too much time hadn't passed. Location accuracy was generally accurate to within about 10-15 metres, but there were some rogue readings that were hundreds of meters off, as a result of the receiver temporarily losing the satellite signal.