GPS Anyone?

By Bjørn Rørslett

Review Incepted 24 April, 2007

The nice thing about photography is that there are just so many opportunities for nifty gadgets. Big boys love this. Of course, as the user you will designate them "necessities", but let's be outspoken here. Gadgets they are. Some might even be considered useful in some settings, but that's likely not why you purchase them in the first place.

Amongst the more specialised yet potentially useful gadgets is a GPS device. It will register your whereabouts with uncanny accuracy and spot-on timing. Several of the Nikon DSLRs can record GPS metadata directly. These models are D1H, D1X, D2H/Hs, D200, and D2X/Xs. The Fuji S5 Pro, which derives from the D200, now joins the ranks of GPS-enabled cameras.

Obviously a GPS unit needs a linkage to the camera in some way so as to have the positional data recorded. Nikon delivers the elusive (and expensive) MC-35 GPS connecting cable, which only allows certain GPS models to communicate with the camera. Thus, when the shutter is tripped, the GPS data is written automatically to the EXIF header of the file. The Nikons record only latitude, longitude, altitude, GPS time, and heading (with some models), but this data will do nicely when you wish to retrieve the exact shooting location later.

I've used GPS extensively during the last years. When you travel a lot, finding the position of your shot afterwards can be a royal pain and I need the geographical names for the captions of images submitted to my stock libraries. So, having my data base system pull out the GPS data and rewriting them as map coordinates, plus settiing up a direct link to a map server on the internet, has been a tremendous leaf forward for me. And for my recent projects with red-listed species, many of which are extremely scarce and/or protected by law, getting accurate geo-references has an intrinsic scientific value.

Now, to the practicalities. You obviously need a sort of GPS device that connects to the camera and based upon my experience in field, this device should be unobtrusive as well. The latter requirement goes directly against the Nikon proprietary MC-35 approach since that entails a lot of (long) cables and interconnections. My firstr round with GPS involved the Garmin eTrex, the Garmin GPS-PC serial port cable, and the Nikon MC-35. While it worked, it also was a true mess for field use. Later, I did experiment with a makeshift hybrid of a Garmin OEM GPS plus the MC-35, where I connected the GPS directly into the MC-35 and obtained the necessary power from the power line of the MC-35 unit (which itself draws power from the camera). Simultaneously, I shortened the cable length of the MC-35 to be more practical. This setup worked quite well and I've used several of these units for about one year. The main issue with them is that the unit constantly is ON, thus battery drain is a potential huge problem in cold weather. I live and work in Norway. This is a country with cold climate. Also, I found the Garmin OEM unit to have quite long start-up time and erratic response once the sky view became severely constrained. In my country, there are mountains, lots of them. And they block the view all the time. So it goes.

While I was researching alternative GPS solutions, I stumbled upon the products from the Hong-Kong based small company DawnTech. They made the di-GPS unit, claimed to show impressive GPS signal sensitivity, and since it has its own connecting cable, you could just hook it up to the 10-pin receptacle on the camera and you are good to go. When unit is switched on, a "GPS" signal appears on the upper display of the camera. Initally the signal flashes to become steady when the location is acquired. Concurrently, a small red LED on the di-GPS is lit permanently.

The di-GPS is powered by 4 AAA cells and comes with a small pouch that can be attached to the camera strap. It has a switch to allow it to be "on" permanently or go active only when the camera is turned on ("Auto" setting). Later, DawnTech added the smaller di-GPS Mini N2 to the product range and the existing di-GPS was rebadged as the N1. Unlike the N1, the new Mini draws power from the camera, but it does provide the user with an "Off" control. Both models come with a 2.5mm mini-jack port for plugging in cable releases. You can order a Nikon MC-30 based release with either di-GPS model, or use suitable releases fromn other vendors (Canon, for example!). DawnTech also sells GPS software, but since this program won't recognise Nikon raw (NEF) files, only jpgs, I found it not worth while to install on my production computers. There are a host of utilities which can extract the needed GPS information for you.

The N1 as standard comes with a metal bracket that allows you to clamp the GPS device to the side of the camera so it gets out of the way. However, in this position it will easily get its fair share of knocks and bumps, plus you lose the possibility of using an "L" bracket or other tripod accessories. I put the N1 upside down in its little pouch and attached it to the camera strap, so it would be less easily fouled by bad weather.

After a di-GPS obtains a satellite fix, a process that can take up to a minute the first time, it will get new coordinates in just a few seconds. So in an open landscape, having the unit set to "ON" or "Auto" (or "Off", N2 only) only matters for power consumption, because it will acquire GPS coordinates nearly at same speed for either alternative. When you get into more difficult terrain, this behaviour changes. If you can allow more power drain, the "On" setting then is to be preferred, unless you accept some delays before the coordinates are available to the camera. In no way does GPS data acquisition impede the camera's operation: if the GPS data is available, the values are written into the EXIF header of image files (NEF, jpg, or TIF), if no data is available, well, then the camera does just fine on its own. Any recorded GPS location data becomes instantly available when you inspect your files on the LCD screen.

My Nikon D200 (UV-modified) and the UV-Nikkor lens, enhanced with a di-GPS N2 Mini GPS receiver. This unit was custom-modified with a 10-pin connector by DawnTech upon my request.

Above is the D200 with a di-GPS N2 Mini attached to the flash shoe. It can also be put on the camera strap if you prefer this solution. Being so small, it is hardly noticeable and won't interfere with camera operation and shooting at all. NB: this version is a customised N2 Mini kindly provided by DawnTech upon request, it has a 10-pin connector so I can connect a cable release or remote control gear. The standard model has a port for a 2.5mm mini-jack plug which I didn't wish to have. The reason for this is that the connection is vulnerable if the camera is heavily used, and I need a reliable connector for a remote release since much of my shooting is performed with tripod-mounted gear. I have urged DawnTech to consider providing their units with the 10-pin instead of mini-jack port.

After working with the two models of the di-GPS (N1, N2) under a wide range of environmental conditions, from nasty winter weather (-25 ºC, snow, and wind) to rain and scorching heat, I can vouch they operate reliably. Initially I was more than a little worried that the units were insufficiently weather sealed, but so far after 7-8 months of field use I haven't encountered such issues. GPS accuracy will depend on the number of satellites the device can get bearings on. In general, the latitude and longitude coordinates had a joint horizontal RMS error typically less than 15 m (best with an entirely stationary camera, might approach 5 m), unless I moved indoors, a condition in which would lead to more erratic GPS recording. Nevertheless, I achieved satisfactory GPS data even in a subterranean parking facility, so that shows just how sensitive these units really are. DawnTech claims they are developed for use in "urban canyons", which I take to imply the di-GPS models can be used in major cities where high-rise buildings block much of the sky view. I've tested this as far as the modestly sized architecture of Norwegian cities allows, and the claim seems pretty valid. You do get less accuracy in the GPS data, however, than in the open landscape. Altitude readings tend to be pretty reliable when the camera is kept stationary in order to shoot a sequence, but fluctuate significantly when you move fast. Not a big point of concern, though, since once you get the position on a map (or from online map servers such as Google), better estimates of elevation can be deduced.

Power consumption of the N1 tends to verge on the high side and you are advised to carry spare batteries in the field. Also, the user should be warned that it is imperative to switch the camera completely off, even when the N1 is set to "Auto", since it otherwise can be repeatedly "awakened" by the di-GPS and thus the camera battery also will be drained over time. With the N2, its power consumption seems to be a little lower yet you should put the N2 to "Off" instead of relying on the standby "Auto" position. If the N2 is turned entirely off, it evidently won't exert a power drain from the camera no matter how the camera is set up so this is the safest procedure.

In conclusion, the two di-GPS models can be just the solution for your camera if you want real-time GPS locations in your digital images. Having these small, responsive units tucked away with the camera instead of fumbling with unwieldly cables and connectors is a relief. Meander over to the DawnTech web site and have a look at their product range. Prices are not low but seem reasonable, in particular when you factor in the costs of the various cables and GPS units otherwise needed.