Nikon D300 User Manual page 503

Nikon also suggests that you keep a handheld GPS unit (e.g.,
Garmin eTrex) at least 8 inches (20 cm) away from the
camera. Maybe it outputs enough electrical interference to
cause problems for aftermarket GPS units. However, the
Nikon GP-1 GPS unit mounts either onto the camera's
Accessory shoe or on the camera's strap, with the included
GP1-CL1 strap adapter. Evidently the Nikon GP-1 GPS is
shielded well enough that mounting it onto the camera's
Accessory shoe is no problem.
My Recommendation: Get the Nikon GP-1 GPS unit! It's
easy to use, foolproof, and has all the cables you need for
using it with the camera. The only other cable you'll need to
buy is the optional MC-DC2 shutter-release cable. I use the
tiny Nikon GPS unit constantly when I'm out shooting nature
images so I can remember where to return in the future.
Many of the newer aftermarket GPS units are not compatible
with the D300(S) since they use a USB cable for interfacing.
That's a good thing or a bad thing, according to how you look
at it. The bad thing is that your brand-new USB-based GPS is
useless for recording data to your images.
The good thing is that you can buy older GPS units for very
little money on eBay and even new old stock from dealers. I
®
bought my Garmin eTrex Legend mapping GPS on
Amazon.com for just over $100 USD. It came with a D-sub
9-pin data cable. I had to buy the Nikon MC-35 cable, and I
was all set!
Primarily, just be aware that the GPS unit must have a way to
connect to the Nikon MC-35 cable in order to interface with
the D300(S). Maybe a future firmware upgrade will give us
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