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Distance Measuring Devices - Glossary of Technical Terms
March 2012

Today’s golfing DMDs embrace a wealth of technology from laser-based rangefinders to GPS devices sporting a variety of graphics, interactive features and game analysis gizmos to play with both during and after your round. We invited Roehampton assistant club pro, Richard Weeks, to take some of the latest models for a test drive and offer up practical tips on how to make the most of both types of device. Following that, equipment editor Dominic Pedler guides you through a glossary of the essential technical terms

1. How Distance measuring devices can help your game
2. Distance measuring devices terminology
3. Reviews


Golf Course Library and Downloads

While many models now come preloaded with anything up to 40,000 courses worldwide, it’s important to think of the nature of the data and what you actually need. The Golf Plus Caddie Lite only takes 10 courses at a time – but that might enough for you, while Sonocaddie’s 2,400 UK courses will be plenty for most of us. Of course, most operators allow you to log into their site to download additional courses and, where applicable, updated versions of existing courses that reflect any recent changes.

In Richard Weeks’ test he notes that some, like the Sonocaddie and SkyCaddie SGX need to be connected to a computer before you can use them to their full potential, while others like the GolfBuddy are ready to go ‘straight out the box’. Look out, too, for Auto Course Recognition (as, say, on the Bushnell Hybrid) which displays your exact location without having to click through the library.

Meanwhile, how that data has been compiled, its accuracy and presentation are important issues that we now look at under various categories.

Course Mapping: satellite or “ground verified”?

While most golf GPS operators map their courses with reference to aerial imagery (usually satellite photography or in some cases helicopter flyovers), some – most notably SkyCaddie and GolfBuddy – map on foot with a team that walks each course, pinpointing greens, tees, hazards and other selected landmarks as they go. These ‘ground verifiers’ argue that the alternative mapping from the air relies on images that may be several years out of date, and whose data is delivered through a complex jigsaw of individual digital pixels that can lead to significant distance distortions in terms of the final picture as a whole. They also point out that any aerial photography is often compromised by tree-lined fairways than can hide bordering hazards and the vital extremities of greens. Walking the course undoubtedly also allows for higher standards of green mapping with, for example, SkyCaddie’s SGX’s IntelliGreen Pro feature including figures to false fronts, ridges and tiers within greens – details that are unattainable from ‘above’.

Accuracy of Distance Data

Some GPS companies claim that there can be wide distance discrepancies between different brands, due not merely to the different methods of mapping just mentioned, but the actual satellite tracking technology adopted and the sophistication of the hand-held unit. SkyCaddie, for example, publishes the formal ‘error factor’ for its SGX that specifies that 95% of the time the yardage displayed is correct to within 1-3 yards thanks to a special omni-directional GPS ‘engine’ that locks quickly onto the appropriate satellite. [Incidentally, this accuracy is far higher than SatNav where locations do not need to be pinpointed to the same level of detail.]

However, while there are reports that different units can display differences of up to 10-15 yards for any given shot to the green, this was not borne out by our own impromptu tests.

Satellite Imagery and Video Flyover

While most GPS units display graphical representations for both their full-hole view and green close-ups, some offer high-quality aerial imagery that makes for a strikingly realistic contrast. The Callaway uPro is a case in point while this system and the Sonocaddie (the latter as a subscription add-on) also offer an aerial ‘flyover’ feature using actual helicopter footage similar to those used on TV during tournaments. This is visually impressive stuff and can be especially useful for unfamiliar courses and, obviously, doglegs and blind holes – though many would regard it as a luxury.

Full Hole View

For many of us, the overriding feature of a GPS will be the three numbers that state the distance to the front middle and back of a green as we ponder our approach. If this is all you require (along, perhaps, with distances to a handful of hazards) then the more basic units like the Caddie Lite should be considered. Others will demand the ability to see a full-hole view with more comprehensive images and data. This takes up more space, so most units limit you in some way.

For example, the Sky- Caddie SGX allows this for 50 of your favourite courses at any one time, with its HoleVue function allowing you to zoom-in to any point on the hole, for example to check your distance to the 100-yard lay-up point on a par-5.

Subscription/membership Schemes

Here is another Great Divide within the industry. While GolfBuddy, for example, offers information for thousands of courses without any further financial commitment, others like SkyCaddie require you to take out one of four subscription packages to an online membership, starting at £29.95 per year.

In our detailed review for Issue 94, last year, SkyCaddie chairman, Richard Stamper, explained “Membership is our customers’ insurance policy that their GPS unit is operating on the most reliable and updated data possible,” referring to how some rival systems using often outdated satellite imagery also risk ignoring new hazards – and even new routings – that are part of the evolution of many golf courses. Membership also gives you access to various scoring and online community activities – see below.

Some other units work with payment packages in different ways. For example the Callaway uPro has a full ProMode option requiring a subscription package starting at 66p per course though their BasicMode limiting you to essential distances to hazards and greens is free.

Self-editing Facilities

This is a potentially important feature – both to insure yourself against out-of-date mappings (see above) and to incorporate your favourite on-course reference points that may not be included in your download. In this way, you can customize yardages to and from particular trees, bunkers, ridges, etc, irrespective of the mapped data.

While this type of personalised course info is most visual on the full-hole colour screen units, such as the Sonocaddie V500, it can also be done on some simpler units like the GPS portion of the Bushnell Hybrid. Indeed, if your golf course hasn’t been mapped at all you can do it all yourself with a bit of patience next time you play.

Touch / button Positioning

In theory this is a fantastic feature, allowing you to touch any point on the image of the hole and see the distance to that point and from there to the green. Ideal for picking a lay-up spot on a par-five, or short of a transverse hazard. While this worked on the all the units that offered it, in practice it was sometimes fiddly and required a certain knack to move the virtual flag around with the tip of your finger or a tee peg. Accordingly some golfers may prefer the button navigation units that work to the same end.

Scoring/stats Features

Top-of-the-range units allow you to input your scores as you play and calculate stats with varying degrees of sophistication. These vary from the basic digital scorecards on the Sonocaddie, to systems that automatically determine the Stableford points for everyone in your fourball if you input your handicap and the relevant stroke indices (as on GolfBuddy’s ProPlay function). Similarly, the best units let you record your percentage of fairways struck, greens in regulation, sand saves and putts to identify where your game is solid and weak.

Online Community

Offering an exciting glimpse of the future are those GPS devices personalised to act as a portal to a host of online opportunities connecting golfers to golf courses, instructors, new equipment and to each other. The standout example is SkyCaddie’s Club SG Beta, where new SGX owners can ‘sync and store’ their game data in a personal performance locker, track their key stats, learn about other courses and connect with other golfers.

Smart Club Technology

This isn’t available yet but SkyCaddie’s ingenious vision in this area is worth reporting to show where GPS technology might be headed. Smart Club technology will allow each club in your bag to interact with your GPS unit via a tiny ‘intelligent’ chipequipped disc inserted in the top of the grip. The unit can then gather data on when, where, and how far you hit each club in the bag, thereby compiling a complete statistical profile of your individual game. This information could conceivably even help you be custom fit online, or inform your coach as to your progress. Actual ‘on course’ club recommendations calculated and displayed on your screen is a logical evolution (though this would face a rules ramification) while the same technology would let you know when you’ve left your sand iron by the last green…


Our units varied considerably in terms of their structural design, from the smart shiny casing of the Sonocaddie and SkyCaddie to the tough rubberised exterior of the Golf- Buddy World and Callaway uPro. Screen size and resolution is also a factor: those on the Sonnocaddie and SGX were particularly sharp and clear even in bright conditions, while the GolfBuddies allowed for brightness adjustment, with a lower clarity implying an energy saving benefit.

PART 2 – Lasers

Although several GPS systems allow you the option of moving the virtual flag around on the green to give you a more precise yardage, there is nothing more accurate than picking the flag out directly with a laser DMD.

In contrast to GPS, these work by means of a special beam that is fired at the chosen target with distance determined according to the time taken for the signal to be reflected back to the unit. Within a second or two the resulting yardage is calculated and displayed. Laser fans argue, with some justification, that their method blissfully avoids any of the GPS mapping issues, finding the course as it plays on the day while being ready to go with no annual fees or additional downloads. The typical lithium battery adopted also avoids the recharging ritual that GPS involves. But while the concept is far simpler than GPS, a few other factors and features are worth considering.


The precise maximum range will vary, in practice, according to the type of target being ‘shot’. While large, reflective surfaces and trees can be measured at greater distances, flagsticks typically have a shorter range. Nevertheless, all these units offer at least 300 yards which will be enough for most of us, while the top units can measure 1,000 yards or more.


The ability to use the device as a monocular is particularly useful for getting visual close-ups of green and bunker complexes and nuances that you might miss with the naked eye. Magnification rates are usually either x5 (eg. Bushnell Tour V2), x6 (Nikon 350G) or x7 (the Leica and top-of-therange Bushnells).

Look out, too, for lens coating systems that help disperse water in rainy conditions, such as the Bushnell RainGuard or Leica AquaDura, while the Nikon is waterproof if you were to drop it briefly in a 1-metre deep stream.

Construction and Size

These vary from the heavy duty plastic of the smaller Bushnells and Nikon to the rubber protected Bushnell Pro 1600, and the luscious, carbon reinforced die-cast aluminum casing of the Leica. While the smallest, lightest units are very compact, some golfers will prefer the same technology in a larger body as this is easier to hold steady when operating. The Leica was very ‘spectacle friendly’ thanks to a rubberised eyepiece that rolls flat.

Pin Seeking Features

This is a useful feature that improves your margin and error when aiming the laser at the flag and trying to avoid a tree or other object on a similar line beyond. All the top devices have this, called variously PinSeeker (Bushnell), First Target Priority Mode (Nikon) or First Target Logic (Leica). The technology usually works by measuring two distances on a similar line and defaulting to the closer. Do note, however, that while this has improved the performance of laser rangefinders considerably, they can still be difficult to use in extreme wind conditions.

Scan Mode

Another popular feature. This allows for continuous measurements as you rotate the viewfinder and home-in on different targets. Keep the button depressed and the readings flash up in sequence (over a duration of eight seconds in the case of the Nikon 350G).

Slope Feature

A useful feature that automatically adjusts the yardage to take account of elevation changes. See Richard’s tip on how this works in practice, though note that Slopefriendly rangefinders are non-conforming as regards the Rules of Golf – even if the feature is not used!

Different Distances?

With all these DMDs at my disposal I was fascinated to see what the distance variations between them might be but was soon surprised at how consistent they all were. For example, I stood by the new junior tee plaque on Roehampton’s 4th hole, which the club had recently installed at a carefully measured 158 yards to the centre of the green. All of the GPS devices in the test displayed a reading between 157-159 yards, with the SkyCaddie SGX showing 158 yards exactly.

Of course, for the better player wanting the exact distance to the pin, a laser DMD would now be much more useful – yet all our units gave a figure to within one yard of each other for the particular flag prevailing that day. I also ran a few spot checks on some the 150-yard marker posts on the Roehampton fairways. The inaccuracy of some of them surprised me and I’ll know in future always to carry a DMD with me and not rely on the markers! Again, this is something to think about at your club – have you often felt a particular approach shot plays shorter? Or has your drive on a certain hole never gone as far you thought it would? Maybe it’s worth picking up a DMD and testing the accuracy of each hole’s details.

Reproduced with kind permission of Golf International Magazine

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