This is just a test of the GPS inside the camera. If you want a full review of picture quality, RAW file formats, lens focal lengths, etc. it's best to wait until a site like dpreview.com or kenrockwell.com do a full write-up. Currently the camera is so new (even Flickr isn't tracking the P6000 yet) that no full-length reviews are available.
I'll jump right into the accuracy testing, and then will finish up with a few general comments about the GPS hardware.
Accuracy TestsIn all of the examples below, the marker labeled "A" marks the spot where the Nikon P6000 GPS thought I was standing or driving (more on shooting from a car below), and the marker labeled "B" indicates the correct position.
Shooting from a position where you have a clear view of the sky
Below are photos I shot with the camera once I'd turned on the GPS and allowed it to get a strong signal from six satellites. Under these conditions, the error is approximately 3-10 meters (9-30 feet).
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Shooting from a moving car
I was curious to see how the Nikon P6000 would perform when shooting from inside a moving car, where the GPS would have a limited view of the sky (I was in a minivan, not a convertible), but would still be able to track a few satellites through the windows. Despite having been in the car for more than 10 minutes (and thus not having a clear view of the sky for that time), the GPS performed remarkably well. The error was between 30 and 100 meters (90-300 feet) under these conditions.
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Taking a photo after having just left a building
What happens when the camera has no view of the sky for a few minutes, and then is taken outside again? In this case, I left the camera inside for about 10 minutes, then went back outside. I let the camera get an initial track on a few satellites, but didn't give it the time it would need to track 4+ satellites and thus get a more accurate reading. This seems to me a reasonable test case, as many users will go inside a building for a while, and then come out and start shooting very soon after having a view of the sky.
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Performance was not bad (about 36 meters/110 feet off). In this case, it would have been more accurate to not have let the camera get a fix on my location at all, and have it fall back on its last recorded position (right before I entered the building on the right of the map above).
Shooting inside a building (i.e. no ability to track GPS at all)
In this case, I took a photo after having been inside a shopping mall in Prague for more than half an hour. Thus, there was no chance that the GPS in the camera could get a reading. What the camera did do was use the last valid GPS position that it had recorded before it lost satellite reception, placing me at the entrance to the mall itself. This seems to me a very satisfactory solution (more on this below).
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Other comments on the GPS in the Nikon P6000It's very slow to get an initial position
When I took the camera out of the box and turned on the GPS, I actually thought the GPS in the camera might be broken. Even standing in the middle of a parking lot with a clear view of the sky, it took over 10 minutes for the camera to detect even the first satellite. While it's not unusual for a new GPS unit to take a while to get an initial fix on its position (the GPS has no idea even approximately of where it is; for all it knows, it might still be at the factory in Vietnam), an initial startup time of more than 10 minutes is excessive, and might lead other purchasers to believe as I did that the GPS is actually broken.
What's more disappointing is that the time to fix an initial position, after the camera has been off for a few hours, can still be 3-5 minutes depending on your view of the sky. I think some users will not pay enough attention to the GPS and will start shooting before the GPS has a chance to fix a position, leading to photos with no embedded GPS data.
Once you do get an initial fix on position, the camera updates its position data every 5 seconds, and this works well. If you switch to "GPS" mode on the camera (the display will then show a live update of your GPS coordinates as you move) it's clear that it tracks well. It's just that it'd be nice if, after leaving a building or turning on the unit in the morning, it wasn't necessary to stand out in a clear area for five minutes holding the camera up in the air before taking the first picture.
No "accuracy" info on the GPS display
Although the camera will show the location of satellites that it is tracking and your current coordinates on the display when in "GPS" mode, it is missing the all-important "accuracy" number. A dedicated Garmin GPS unit will not only show how many satellites it can see, but also an estimate of the accuracy of the coordinates that it is reporting. This is very useful when trying to determine if you are standing too close to a building, or under too much tree cover to get a good reading. The Nikon P6000 simply uses a three-segment display to show accuracy, and the third (best) segment seems to light up whenever accuracy is better than about 50 meters / 150 feet. This is not good enough. Hopefully a firmware update can add accuracy numbers to the GPS display, or at least add another few steps to the accuracy scale.
Writing GPS data to EXIF headers with no view of the sky
When you go inside a building, or any other area where GPS can not be used, the camera will use its last position to tag photos with location data. You can set the "time to live" of this GPS position data, which is very useful. How it works is this: you tell the camera the maximum age of the last point to use when tagging photos when it can't get a current fix on position. You can set this to anywhere from 15 seconds to two hours. Thus, if you have a "maximum validity" of one minute for GPS data, and you take a photo 30 seconds after losing contact with the satellites, you will get GPS data in the photo, but if you take a photo 90 seconds after losing contact with the satellites, you will not get GPS data in the photo.
Assuming that a user sets this to something useful like 1-2 hours, this will be a great feature for tourists. You won't be able to track yourself as you move around the Louvre in Paris, but at least all your photos from your tour of that museum will be tagged with a location at the entrance to the building. Good enough.
You can set the date and time on your camera using GPS
You can set the time and date on your camera (but not the time zone) using the built-in GPS. This seems like an obvious thing for the software to support (of course, you never know; the iPhone still doesn't support cut-and-paste), but I'm still glad they included this feature. My experience with other Nikon cameras like the D40 is that the on-board clock is quite inaccurate.
What's the GPS chipset in this thing?
None of the spec sheets that I've come across were able to tell me what GPS chipset is used inside the P6000. Knowing this would have given me a better idea of what to expect in terms of accuracy. I guess we'll have to wait until someone takes one apart to find out.
SummaryI must say that I am quite pleased with the P6000, and that the accuracy of the GPS is easily good enough to make it useful. For most consumers, even accuracy of 100-200 meters will make looking through travel photos much more enjoyable (no more "Where was this shot?"). For our use, it will also work, assuming we take a few precautions to make sure we always get the best possible accuracy from the camera.
However, if you want really accurate GPS data, especially in more demanding situations (very close to tall buildings, under extensive tree cover, inside a moving vehicle, etc.), the best route is still a camera paired with a dedicated GPS unit, either tethered directly to the camera, or recording your track to be synchronized with the photos later using an application like GPSPhotoLinker.