Spyglass for iOS: Powerful Navigational Instrument

Spyglass is a powerful but technical app for the outdoorsman. It uses the camera, if available, as a viewfinder and overlays a myriad of positional information using every sensor available. Use it as a waypoints tool, sextant, compass, range finder, speedometer, inclinometer and more.

People who would find this app useful include: sailors, hikers & forest service workers, soldiers, amateur astronomers, policemen and surveyors.

A Technical Instrument

This is not a toy app, and it’s not trivial to learn. It makes use of the advanced technology in the iOS device, such as the GPS system (if available), gyroscope, compass and accelerometer, all in concert to provide a heads up display (HUD) overlaid with the camera optics (if available) as a viewfinder. As with any complex technical instrument, like a sextant, there is a learning curve. Unless you spend some time mastering the capabilities, you won’t understand the app or get much out of it.

Spyglass has some military features, so if you aren’t familiar with angular mils and military map coordinates, you can skip those features or do some light reading to get caught up.

Here’s the company’s quintessential screen shot, looking at the setting sun.

Spyglass -1

The list of things that you can do with this app is impressive, and I think its best showcase is the iPad 2 because it has a rear-facing camera and a larger display than an iPhone. Note that assisted GPS is only available with the iPad 3G models. If you’re in range of a Wi-Fi system, it can use that to get a crude estimate of your position, but then, that’s not likely to be available if you’re at sea or hiking in a national park.

There is heavy and beneficial use of gestures to simplify operations.  That’s handy because the app is used while holding the iOS device in lots of different positions. Here are some videos that give you a feel for the operation of the app.


I can’t begin to get into all the settings and features in this review, but a quick summary should help you decide if this app is for you.

  • Determine elevation of an object with inclinometer.
  • Determine angular position between two objects.
  • Determine range to an object using the military reticle technique.
  • Determine latitude, longitude, speed and heading.
  • Overlay a compass on a local map.
  • Zoom the camera/viewfinder image.
  • One button snapshot of viewfinder view.
  • Display the position of the sun, moon, and Polaris (the North Star).
  • Overlay optical filters on viewfinder to enhance contrast.

To get even more of a feel for the app, here are the features added just in the latest version, 3.3:


I noted with enthusiasm that the device can be used in metric or English mode and the compass can be slaved to magnetic or true north. In fact, there are quite a few settings that reflect thoughtfulness on the part of the developer and that will help make the app more broadly useful.


The documentation is awesome in many respects. It can be downloaded as a PDF or EPUB directly to iBooks if desired and is about 60 pages as a PDF file. Reading the manual will give you a good idea if this app is for you, but at a mere US$3.99, it’s a bargain worth investigating no matter what.  In that sense, it’s a lot like Emerald Observatory which I also reviewed.


Mapping Operations

The manual isn’t without its problems, however. The author takes the approach of introducing the features in a general way first. If you’re after the details of how to exploit a feature or understand the display, you’ll be frustrated. The details come later, but you’ll have to dig to find those details because, while the TOC is okay, an index would be a helpful addition. That way, the user can home in on each feature and learn to utilize it.

The manual is also very technically written, and is sometimes either too pedantic, too ambiguous or too terminology laden for the sake of sounding erudite and professional. Apple customers have come to expect friendliness, a touch of humor and great clarity, something sorely lacking in this 60 page manual. Occasionally, some additional step-by-step instructions would help clarify a process.

The Verdict

Despite the technical nature of this app and the imposing documentation, this is, frankly, an awesome app that marries the iOS device sensors, a lot of math, and the graphics capability of, say, an iPad. It shows what can really be done on Apple’s hardware in the hands of a very technical developer and bodes well for the future of the iOS platforms. The fact that it’s priced at just four bucks is even more amazing.

A final warning: a great deal of work learning the capabilities of Spyglass will pay big dividends. Casual use will only result in a beautiful toy to impress friends.

Product: Spyglass 3.3

Company: Happy Magenta

List Price: US$3.99



Performs a wide range of navigational functions utilizing every major sensor of the iOS device. Incredible low price for the value offered.


Pedantic documentation that puts product image before clarity.