Geotagging test of the Nikon D7100 and the Promote GPS N-90

One of the first things I did upon the arrival of my D7100 was to check if it would properly work with my GPS, because the one thing that I have been missing dearly during my recent travels was the ability to properly geo-locate my shots. Here’s what I have found.

Compatibility and Setup

Unlike the D200, the D7100 does not show the GPS icon of my Promote on the top control panel (fig 1, right), which had me initially worried that it was not compatible.
Fortunately, the rear display does show the GPS icon, either blinking when the device is acquiring the necessary satellites or steady once so-called “lock-on” has been achieved (fig. 2)
Still, this is annoying because you must either push the i or the info button to confirm that the device is properly connected, while it cannot be confirmed at a glance, as it is supposed to.
While Nikon’s own GP-1A will likely work properly, other third party devices may give similar results. Meanwhile, the D600 apparently suffers from the same glitch (if you can call it that).

The camera has a menu to allow you to configure settings for when a GPS device is connected, which can be found in the Setup Menu, page 3: “GPS”.  This is also an alternative for confirming data acquisition (fig 3 - Position).
The GPS menu contains three items: “Standby Timer”, “Position” and “Use GPS to set camera clock”.

Standby Timer

Normally, the exposure meters turn off automatically if no operations are performed for the amount of time set in CSM c2 “Standby Timer”, however, the camera will extend standby by up to one minute if this item is set to “Enabled” and a GPS device is connected, to allow time for it to achieve lock-on.
The purpose of enabling this override is to avoid unnecessary drain on the battery, and it may suffice for so-called hot starts.
Nonetheless, for cold starts this is likely not sufficient, which is why the standby timer can be disabled when the camera is connected to a GPS device and why I have set this option to off, for now.

Keep in mind though, that even if power consumption is pretty minimal (± 55 mA), continuous use may drain the camera battery after about 4 hours, as I found out with the D200 during our visit to Machu Picchu.
Your mileage may vary, depending on your settings, the camera’s power management and the condition of your battery.

While with the D7100 you may alternatively choose to repeatedly half-press the shutter-release button or any other button (AE-L/AF-L, for example) to prevent the meters from turning off, on other Nikons it may be the only alternative to avoid the camera – and thus the GPS – to power down before acquiring lock-on (e.g.: D3, D300, D700).
Also, with cameras like the D2 and D200 the GPS does not power down with the meters, which means that you need to turn it off manually with its on-off switch, or risk draining your battery faster than you’d ever like.

Position, use GPS to set camera clock

The second item, “Position” will be grayed out when no device is connected or while the device is establishing communication with the camera, after which it will turn white, while GPS data becomes available after lock-on.
Apart of Latitude, Longitude and Altitude, the camera can also record Heading (Azimuth), which will register the direction in which the camera/device are pointing if and when your GPS supports a compass function, which mine – evidently – does not.
Finally, you may decide to sync the camera clock to the time informed by the GPS device, which uses UTC or Coordinated Universal Time.
However, it does not include location correction (+/- X hrs.). Because of the latter alone, I have this option turned off.

In its eternal wisdom, on the D7100 Nikon has changed the location of the accessory terminal in comparison with the D90.
As a result, the plug of my Promote sticks out awkwardly below the camera body (fig. 5). This also leaves the connection cable a little tight for mounting the GPS on the hot-shoe (see top image).
Fortunately, it comes with a clip to allow you to fix it to the camera strap, where I prefer to carry it anyway in order to keep the hot-shoe available and also to avoid blocking the pop-up flash.

Cold and Hot Start

Cold start refers to the time that it takes a GPS device to capture signals from satellites in a new location, or at the last location after having been turned off for a long time.
The GPS icon on the information display (or top LCD panel) of the camera blinks until lock-on is acquired, which indicates that the device has established and locked communication with the satellites needed to fix its position (at least 3). After lock-on, the icon goes steady.
In my initial tests my converted GPS-N1 (article here) took up to 4 minutes, which is longer than it used to take with the D200. That said, lock-on delay depends heavily on location and visibility of the sky, and in my experience it may vary greatly from location to location.
Curiously, the second Promote I tested was somewhat quicker at lock-on, but very imprecise to indicate altitude. Still, this improved steadily during the following 10 minutes or so, which may be due to the fact that for proper altitude indication up to 6 satellites are required.
With an unobstructed view and a clear sky, the delay ought to come down to around 2 minutes, typically, although I still have to confirm this with the D7100.

Hot start refers to the time it takes a device to re-establish its position at a location previously acquired and/or after a short(ish) power down.
With a clear, unobstructed sky, the Promote on the D7100 could take as little as 15, but up to 40 seconds, which is again longer than it used to on the D200 (about 10-15 sec.)
What not has changed is that, even when entering a space with zero visibility of the sky and without turning the camera off, it generally manages to maintain lock-on.
In case of signal loss, it suffices to go near an unobstructed window to quickly re-lock position, in most cases.

Conclusion

Even though not tested extensively, my Promote GPS apparently works properly with the D7100, even though it is slower than I was used to.
Once lock-on is achieved, LAT/LON data is consistent and, even though a second device initially got ALT wrong, this was remedied within the first 5-10 minutes of constant use.
Promote may have to change their cable configuration to accommodate various post D90 cameras which feature an inverted and/or relocated accessory terminal, but they are hardly to blame for Nikon’s design inconsistency.
Moreover, Nikon have apparently changed something in the connection itself to cause the GPS icon not to show up on the top LCD, at least for my device.
Even though they may believe that this may thwart competition for their own GP-1A (SRP $ 312), the only thing they really do is frustrate loyal customers.
Apart of working properly with the D7100, the other good news is that the Promote has become even more attractive as its price has come down from USD 149 to USD 99.

In other words: highly recommended, especially considering that Promote’s customer service is among the very best, in my experience.
Compatible with: D1X, D2, D3 and D4 series, D5, D200, D300(S), D500, D700, D800 series (Promote N-1, ten-pin) D90, D750, D7K series, D600 series, D5K series*, D3100/3200/3300 (Promote N-90, accessory terminal). 
* The Nikon D5300 has built-in GPS and Wifi, the D5500 and D5600 only WiFi.
The Nikon D100, D40(X), D50, D60, D70, D80, D3000/3400 are not instantaneous geo-tagging capable.

Manufacturer Website: GPS Receivers.
For an in-depth review of the Promote GPS-N1 and a comparison with other GPS alternatives, check out this article: “Geotagging” with your Nikon. Review of the Promote GPS-N1

You may also want to read:

Competition for the Nikon GP-1. Promote Systems launch their GPS N-90
Promote GPS 10-pin CA10 to D90-type CA90 connector conversion
Geo-tagging Flickr images: the coolest game on (Google) Earth