Dunce-cap question: What is the science behind rangefinders?

[JessN16]

Specifically, how do they get yardages and how accurate are they?

If I keep getting back into the game, I'm either going to eventually go with one of the GPS systems or a laser rangefinder. The rangefinder is attractive to me because I play a lot of courses that probably aren't mapped (i.e., cheap golf places in the rural South). But if it's not accurate, I don't want it.

I'm guessing these things use some kind of laser bounce-back system not unlike LIDAR, but how difficult is it to, say, try to get yardage to the pin and end up really getting yardage to a tree behind the green instead? Can you get yardage to a point on the ground (like the front edge of a green, or a bunker)? And assuming they're accurate, how much should I prepare to spend for a competent one?

Thanks,
Jess

[michaeljames92]

Yeah I'm pretty sure rangefinders do (similar to speed guns) send out a radio signal or some sort of electromagnetic wave, which I think bounces off the nearest object, and judging by the relay time that the wave takes to come back to the rangefinder, it can calculate distance. There are some great reviews on this site by Iacas on the Leupold rangefinders. Have a look around, there are some great articles.
On your question of accuracy, there is a crosshair (can be changed) on the screen which you can pin point distances with. Iacas explains this pretty well in his review.

[deronsizemore]

I can't tell you how the technology works, but I have the Bushnell 1500 w/out slope and it's probably the single best investment I could have made last year. It's extremely accurate +/- a yard up to like 500 yards without a reflective surface. It goes to 1500 yards when shooting a reflecitve surface I believe.

It's helped a bunch with my distance control.

[iacas]

  michaeljames92 said:

Yeah I'm pretty sure rangefinders do (similar to speed guns) send out a radio signal or some sort of electromagnetic wave, which I think bounces off the nearest object, and judging by the relay time that the wave takes to come back to the rangefinder, it can calculate distance.

All right except the parts about the radio signals: they emit a laser beam, which is fairly small and which will hit whatever you're aiming at and little else (small radius), so you can shoot through fairly small gaps between trees and still get a yardage to the flag, etc.

The Leupold is the best I've found at $299 (US). Small, fast, accurate. Lasers are accurate to a yard or less. GPS is +/- 3 yards, which means they can be off by as much as six yards since they require two measurements (+/- 3 when the course is mapped, +/- 3 when you get a reading).

[wachesawgolfer]

I wonder if they are similar to the rangefinder camera and actually emit two laser beams and where the two beams intersect on something in the viewfinder circle, the distance is computed by using the angle of the intersection or triangle created.

[Smallville]

  JessN16 said:

Specifically, how do they get yardages and how accurate are they?

The rangefinder is awesome, in fact I have used one for years, but the gps is more user friendly, in my opinion (just look and it gives you a yardage instead of aiming and clicking to get a yardage. As far as accuracy, the rangefinder blows away the gps. But at my skill level I don't need spot-on yardage. If I get it on the green, that's a plus. I'll take my chances from there. Some of these guys can hit it pin high all day long. I can't, and I would guess that most people can't. Although people who would sign up for a golf forum might be better than average, I am definitely an exception to that rule. As long as you know the pin is in the front, back or middle of the green gps is great. As far as your courses maybe not being mapped, go to the major gps websites ( www.golfgps.com is for GolfLogix, whichis what I use, a search will get you skycaddie and others). You can look to see which courses are mapped. And if they aren't mapped, I emailed them about a 9 hole farm course in rural Iowa that wasn't mapped and they had it mapped in a week. The better guys like the rangefinders better than the GPS units because of the accuracy. I can't argue with them on that because they are right. But for your middle- to high-handicappers, and there are a whole lot more of us out there, GPS should be fine.

[iacas]

  wachesawgolfer said:

I wonder if they are similar to the rangefinder camera and actually emit two laser beams and where the two beams intersect on something in the viewfinder circle, the distance is computed by using the angle of the intersection or triangle created.

No, they don't work that way at all. There's no focus adjustment on a laser rangefinder.

[mkrolewski]

A range finder emits a laser beam and times the round trip interval from the finder to target and back. This is then converted to a distance. Accuracy to +/- a yard seems reasonable. When using a range finder you can target any reflective object on the golf course. The laser technology is getting better as to what is reflective or more correctly how little of original beam must be returned for a measurement to be made. The original ones actually needed a reflector.

The laser is typically an infrared (IR) laser, invisible to the human eye and is supposed to be eye safe. I am not sure if this has to do with the frequency or the amount of energy in the beam. Eye safe means you or someone else standing in the line of the laser could look directly into the beam without any permanent damage to their eyes.

Not knowing all the internals, they generally have a "mist/rain" capability to reduce the inadvertant timing of a reflection off a rain drop or fog between you and the target. I would suppose there is a sampling algorithm involved eg 10 measurements of one distance, 1 of another; ignore the 1, use the other 10. At the speed of light, a 300 meters trip out and back is very short ( about 2 millionths of second ). So the range finder could send and receive many reflections in a single second.

Similarly, most have algorithms to deal with multiple objects in the line of sight eg when hunting and looking through trees, bush and there are multiple targets to select. On a golf course, you are aiming at the pin, but could be measuring the distance to the hill or woods (one or more trees/targets) behind the green. Again, the algorithm generally is set to take the longest or the nearest object.

But you must have a clear line of sight to that object. Thus the pin hidden by a stand of trees is not available.




GPS is working on similar principles. The GPS is a specialized radio that is determine its distance from typically 4-12 satellites at the same time. It converts this information into a position on the globe, typically every second or so. The GPS then compares this position to recorded positions on the golf course eg the green, bunkers, to determine it's distance from them. The accuracy of the GPS system is dependent on the amount of information gotten from each satellite. Military GPS are accurate to at least a yard; a golf GPS and all other non-military GPS is only allowed to be accurate to +/- 3 yards.


GPS on the other hand has no real limits to need of line of sight. The GPS must be able to "see" a minimum number of satellites. Again older GPS had some difficulty with trees blocking the radio signals. My automotive GPS is sometimes confused on streets lined with 150 ft trees ( I live the north west of the US).

Several brands eg SkyCaddie and GolfGuru perform additional computations to locate the line between you and the "hole" and the intersection with the front and back edge of the green along that line. Those GPS are truely displaying the distance to the nearest edge, center and farthest edge from your position. One with only 3 points (F/C/B) are displaying distance to those points. If you are in the middle of the fairway facing the green, this is good enough.

GPS' major limitation is the recorded targets to measure to. If a target/position was not recorded, the GPS cannot determine the distance to that target. Depending on the brand, you have a limited number of targets per hole in the 3-30 range. The vendors seldom track all "significant" objects on a hole. Hence the need to map your own course. To some extent, this is part of the uPro's alure.


From my personal experience with GPS, the biggest most critical target is the green. Most others generally can be ignored. There is a need to get dog leg corners or through the fairway positions, especially if you can reach them with your driver. Similarly, you most likely would like layup positions that you often shoot for.

Generally, there is no easy way to map/record positions of a creek or pond that either borders or crosses the fairway, especially at an angle.

From my personal experience, the GPS is generally a great addition to determining shots and tracking club distances. I try to not to leave home without it.

[JessN16]

Thanks for all the info, guys.

Can you use a rangefinder to determine distance to specific points on the ground; i.e., a fairway bunker?

Jess

[gsu_paintballer]

What's the cheapest device that can be used roughly accurately? I'm a hacker so it doesn't have to be EXACT.

[Smallville]

  JessN16 said:

Can you use a rangefinder to determine distance to specific points on the ground; i.e., a fairway bunker?

By all means, yes. That is one of the advantages of a rangefinder over a GPS. As long as you can see it, you can get a distance from it. The MAIN advantage of a GPS, in my onpinion, is there is no line of sight issues. But when you do have these issues is when it's really nice to have a GPS.

I paid $242.00 Total (unit, shipping and one year membership) for my GPS on ebay. I believe quality rangefinders cost more (it's been years since I bought one and I haven't really researched them lately). The yearly subscription for mine is $30 and that is for unlimited downloads worldwide; which will come in handy next year when we go to Great Britain). If you don't have to have EXACT distances, the GPS might be the better way to go (for some reason I think the cost versus the rangefinder will be close to equal after 5 to 7 years with the yearly download fee). At least in my case with the deal I got. Moreover, when there are changes made to the course downloads (like they adjusted some distances, or whatever on a course), my software will alert me to the change (if I have already downloaded it) and prompt me to download the new version of the course. Apples to apples, a rangefinder will beat the GPS in distance accuracy. There is no question about that, especially since the GPS can not measure pin position. But if front, middle and back of the green is what you need at this point in your game, it is a viable alternative.

[deronsizemore]

I agree with the above, that's one advantage of the rangefinder. I can shoot a bunker or edge of the water and know exactly what I need to clear it. You can literally shoot anything on the couse and get a distance.

As for the line of sight problem, yes, that's one advantage of GPS, but for me, it's not a big enough advantage to make me switch. I think so far this year I've maybe ran into a line of sight problem on the course two or three times. For those odd times when you cannot see the flag, it's pretty easy to get a close to accurate distance: Leave your cart or bag beside your ball; walk up the hill until you can get a shot; turn around and shoot your cart/bag; add the two together and now you've got your distance (or close enough to it).

I find that majority of the time I've encountered not having a line of sight to the flag is when I'm in trouble after a bad shot. Most of the time when I'm in trouble, my goal isn't to go for the flag anyway, so no need to get pinpoint accurate on the distance.

[Fourputt]

I use a Bushnell Pinseeker Tour V2 laser rangefinder. It isn't cheap but I had money on the books in shop and nothing much of interest to spend it on, so I dropped $260 on that. I'm hooked. I wouldn't trade my laser for a GPS for anything. I don't like the limitations of the GPS units (locked into whatever points are programmed, very limited battery power between charges, actual pin location is a guesstimate, and can be several yards off on large greens). I like it best when I need to layup out of trouble, or toward an object that the GPS programmer didn't see a need for. I can shoot the object that I need to be short of, pick a club that I know can't reach it, then swing a way with confidence. How often do you see guys lay up too far and hit into the problem they are trying to avoid? I NEVER worry about that any more. And I've been using my Bushnell all season on the original battery.

I've played with lots of guys with SkyCaddies, and they seem to be ok most of the time. The horror stories about dealing with customer service and the time it takes to get repairs done turns me off completely. I played with a friend yesterday whose SkyCaddy lost its ability to download courses. After trying over the phone to get it resolved, they told him he'd have to send it in for repairs.... he finally got it back 2-1/2 months later, long after the golf vacation that he wanted the courses for. My experience with automotive GPS is that they can be a bit glitchy, with a much higher failure and repair rate than the system in the laser. I've played with 2 guys with supposedly identical SG2's, but one lost the satellite lock for almost 2 hours during a round.... the other one worked without a problem. They never did figure out why the one failed.

All in all, weighing all the pros and cons, I'll take the laser over the GPS as long as the laser has the Pinseeker or similar technology. A simple basic laser without that algorithm is much harder to use with confidence, and there is still often some question as to whether you have the correct target. With the Pinseeker, I can pick out a limp flag from background clutter guaranteed from 250 yards (and if the course has reflectors on the flagstick, from 400 yards)... if you need it better than that, you ought to be on Tour.

[hrossroth]

Thanks espescially for the above post and this thread. I have only seen one range finder or other such device on the course I play. Reading these and other posts about rangefinders has convinced me that they are a good investment for me. I have started noticing when one would come in handy as I play.

I have some clubs that I want to trade in somewhere to get the rangefinder. I went to the large chain store in my area which sells mostly GPS, but some rangefinders. The question that I had wasn't answered. I have dealt with this salesman before and he proceeded to prove once again why he is not my favorite salesman. He thought that I was completely uneducated, and tryed to sell me a GPS. I appreciate that he has a personal opinion but when it prevents a sale going through when the customer is ready to talk final sale... it was frustrating. What he said did have me questioning my decision about what to buy, before I reread this thread. I have never had the chance to use either. The basic components of a rangefinder appeal to me. He said that it was difficult for him to hit the flag when he used one. Does this mean he prefers GPS, yes. Does it mean I still want to try a rangefinder, yes.

[lordhamster]

People often quote the accuracy difference between rangefinders (+/- 1 yard) and GPS (+/- 3 yards) as an important difference between them.

Maybe I'm just a really bad golfer, but I don't think that 2 yards of difference between an actual and a measured distance is going to effect anyone but the very best players. How many of us can consistently put the ball within two yards of a target from 100+ yards out?

The real issue is the fact that GPS devices measure the distance to the center of the green (and other fixed points) and not the distance to the flag.

When I use my GolfLogix, I look at the flag position then guess at which fixed position its closest to (front, center, back of green). Finally I make a guess and swing. Now assuming my shot is 100% perfectly online and goes the right distance I wanted, I can still be way off because I'm essentially guessing at the pin position relative to the fixed points. Inevitably this guess of pin position is much greater than the 2 yard difference in measured accuracy.

I've used both systems and I have to say for me the GPS is a little easier because I stink. Being a bad golfer all I need is a good estimate of the distance. More importantly, I need to know the information very quickly. The GPS allows me to take a glance at the screen and get all the readings I need instantly, thus I don't slow down play.

A few weeks ago, I played a course not mapped by GolfLogix yet (they added it at my request 3 days afterward), and was playing blind. That day I wished I had a laser rangefinder as well. One thing is for certain, no matter what technology you go with, after you use it you'll never go back.

[CosmosMpower]

  gsu_paintballer said:

What's the cheapest device that can be used roughly accurately? I'm a hacker so it doesn't have to be EXACT.

If you already have an iphone 3G you can download a few programs for little to nothing. It's accurate to about 6 yard-10 yards I believe.

[gsu_paintballer]

  CosmosMpower said:

If you already have an iphone 3G you can download a few programs for little to nothing. It's accurate to about 6 yard-10 yards I believe.

I don't, just an iPod touch so unless I find a course with wireless internet I'm stuck

[hamletsdead]

Well, it's called a laser rangefinder for a reason, not just because "laser" sounds cool.

I prefer my rangefinder to GPS, frankly, since it's simpler and quicker and I only use it if I feel like I can't eyeball it at all. I'm pretty good about guess-timating distances, and think it's one of those skills that only develop if you practice it. If you always rely on GPS or rangefinders you get dependent on them.