We've launched the new forums! Read more here

How does "slope" on a rangefinder work?

SuperStroke
White Rhino

White Rhino

SANDBAGGER!!!!!!!
Joined
Nov 22, 2009
Messages
17,314
Reaction score
82
Location
Los Angeles
I have a quick question about laser rangefinders in general. I know there are 2 "versions" one with slope that can't be used in tournaments and such and ones without this feature, such as this hybrid. I understand if you are on a tee that is higher than the flag a unit with slope will calculate the "true" distance to the hole. In the same scenario what would this unit or a unit without the slope feature show if I hit the flag from the tee box looking down.
 
White Rhino said:
I have a quick question about laser rangefinders in general. I know there are 2 "versions" one with slope that can't be used in tournaments and such and ones without this feature, such as this hybrid. I understand if you are on a tee that is higher than the flag a unit with slope will calculate the "true" distance to the hole. In the same scenario what would this unit or a unit without the slope feature show if I hit the flag from the tee box looking down.
Click to expand...

I believe it would be the exact distance that the laser shoots. The length of the line directly between the rangefinder and the flag.
 
I carry a rangefinder and a simple GPS due to the fact that I cannot use the GPS in WMJGT matches. It can also be a lot cheaper to get the Bushnell neo GPS along with a good rangefinder if you find good deals, then you get both separately so you can use the rangefinder in tournaments. The neo is simple and only gives front middle back distances plus a shot distance calculator a lot like the hybrid.
 
If you know math it would use a right triangle and the Pythagorean theorem. The one without slope would be measuring the hypotenuse of the triangle (longest line, opposite the right angle). The one with slope measures the hypotenuse, then figures out how far down it is pointing. Hypotenuse (total distance) = c and elevation change = b. Take the square of c and subtract the square of b and take the square root of your answer for the straight distance that a rangefinder with slope would give.

So if the one without slope says 167 yards and the elevation is uphill 17 yards, the one with slope would say 166. I applaud you if you followed me through all of that :)
 
I know it is a Friday night and I am sitting here voluntarily doing math, but I am a nerd and after fighting my 3 year old to go to sleep for the past 3 hours, this is what I decided to spend my time doing. I can't explain very well in words how slope works so I drew it for you and provided some sample calculations. Here you go.

43aa86d4-ad89-5e0d.jpg


The main thing to know is that the slope rangefinders have an inclinometer inside them that can tell at what angle the device is being held. It uses the Cosine of this angle to compute the relative distance. If the pin is above you then the distance obtained by the laser will be the adjacent side of the triangle and the slope distance will be the hypotenuse. Whereas, of the pin is below you then the hypotenuse will be the actual distance the rangefinder gives you and the adjacent side being the slope distance. Hope that helps.
 
Dr. Teeth said:
Okay now I am even a bigger nerd because I am checking this math, but I don't believe this answer can be correct. Did you mean 45 feet? That should be the right answer and if the elevation was 145 it should affect the relative distance by a lot more than 5 yards.
Click to expand...

This is why they created GPS units and rangefinders with slope....so you DONT have to do math!!
 
Dr.'s math is right solving for a and b. however, it's seams like the downhill should be more than 9 yards less.

Either way it is going to depend on trajectory. Shorter irons are less effected because they land at a steeper angle. Longer clubs travel more in the horizontal direction and therefore elevation change makes a bigger difference.
 
Holy smokes!!! I had no intention of starting a whole discussion of mathematics lol. I understand the concept from the video on the bushnell site that Smalls was speaking about and that one explains it very well. I really appreciate all the responses, I think I will go out later anbuy the Bushnell w the slope feature because it just makes life easier for me.
 
Dr. Teeth said:
Okay now I am even a bigger nerd because I am checking this math, but I don't believe this answer can be correct. Did you mean 45 feet? That should be the right answer and if the elevation was 145 it should affect the relative distance by a lot more than 5 yards.
Click to expand...
That's what they said on the video, 145 feet.


Here is my thinking about slope. It can only give you an idea, unless you are able to input your yardages for each club. Because say the hole is 220 yards out but it plays as 170. I would use my 3 wood for the 220 but my 4 hybrid for the 170. Think about the shape of the shot, and then consider someone who would use a 9I or PW for the 170 yard shot. Their angle of descent would be much steeper, so if they are shooting for the same 170 mark, they would come up short (or I would come up long).

Also, if you are able to input your yardages (and I thought you were able to on some models?), then the resulting number would not work for your buddy if he asks for a yardage. I have never used a slope rangefinder, so I don't know for sure that mhy thinking is anywhere close to being right, just what I am thinking.
 
I guess I am pretty nerdy too, I just finished reading the entire thread and found it interesting & informative. :D
 
Smallville said:
That's what they said on the video, 145 feet.


Here is my thinking about slope. It can only give you an idea, unless you are able to input your yardages for each club. Because say the hole is 220 yards out but it plays as 170. I would use my 3 wood for the 220 but my 4 hybrid for the 170. Think about the shape of the shot, and then consider someone who would use a 9I or PW for the 170 yard shot. Their angle of descent would be much steeper, so if they are shooting for the same 170 mark, they would come up short (or I would come up long).

Also, if you are able to input your yardages (and I thought you were able to on some models?), then the resulting number would not work for your buddy if he asks for a yardage. I have never used a slope rangefinder, so I don't know for sure that mhy thinking is anywhere close to being right, just what I am thinking.
Click to expand...

You can do that with the leupold rangefinders (gx-2 and gx-4 I believe and they will offer a suggested club to hit based on distances, atmospheric conditions, and sea level height versus wherever you first inputed the information.
 
This thread gave me a headache.


Steel Tappin'
 
Steel President said:
This thread gave me a headache.


Steel Tappin'
Click to expand...

Worst part is, someone can give me the exact yardage on a downhill shot, and then I'd just fat it short anyways...:D
 
Add in a 15mph wind in your face and see what happens to the calculation.
 
thedue said:
Add in a 15mph wind in your face and see what happens to the calculation.
Click to expand...
That too! Or a tailwind! But I can see where it can give you some added info that could be beneficial.
 
thedue said:
Add in a 15mph wind in your face and see what happens to the calculation.
Click to expand...

The leupold unit takes into account variances in temperature and feet above sea level from what you enter as a baseline. Very interesting the technology within these units
 
White Rhino said:
The leupold unit takes into account variances in temperature and feet above sea level from what you enter as a baseline. Very interesting the technology within these units
Click to expand...

Wild what these things can do now. How long before you just hand it your club and say do it? :D
 
The angle of descent has little to do with it. Velocity is dimension independent, which means that it has separate velocity for each dimension (x, y, and z plains), and that they cannot be affected by forces in other plains. The only thing that would affect the x direction is air resistance, which every club would have. It would just depend on how long the shot was in the air.

Oh wait, I forgot about spin. Never mind then, I'm not getting into how spin would affect it as well,
 
thedue said:
Wild what these things can do now. How long before you just hand it your club and say do it? :D
Click to expand...
We call that model Daryl....:D
 
Great discussion. A couple of issues: using the video example, what would be the yardage listed on the tee box? the straight line of sight yardage or the horizontal yardage?

I also think that the "playing yardage" is dependent on the club that the player needs to reach the target. If I normally use a 7 iron to play 145 yards and my partner normally uses a 9 iron and we select those clubs i think the 9 iron shot will land short of the 7 iron due to the trajectory. Both will intersect the horizontal line at (about) the same point but the 9 iron is falling at a steeper angle, n'est-ce pas?
 
Jeanthemachine said:
Great discussion. A couple of issues: using the video example, what would be the yardage listed on the tee box? the straight line of sight yardage or the horizontal yardage?

I also think that the "playing yardage" is dependent on the club that the player needs to reach the target. If I normally use a 7 iron to play 145 yards and my partner normally uses a 9 iron and we select those clubs i think the 9 iron shot will land short of the 7 iron due to the trajectory. Both will intersect the horizontal line at (about) the same point but the 9 iron is falling at a steeper angle, n'est-ce pas?
Click to expand...

You are totally right about this, however, the rangefinder has no way of knowing this and so gives you the triangluated distance. The rest is up to the golfer to figure out.
 
Just got back from golf store and I picked up a Bushnell V2 with slope. I got it $100 off list as it was a return but looks to be in perfect shape. Going out tomorrow to play 18 and looking forward to playing around with it.
 
White Rhino said:
Just got back from golf store and I picked up a Bushnell V2 with slope. I got it $100 off list as it was a return but looks to be in perfect shape. Going out tomorrow to play 18 and looking forward to playing around with it.
Click to expand...

I will be interested to see how this works for ya. I have been drooling all over Ebay for one of these puppies for the 2012 golf season :blob:
 
I have not seen one working and couldn't use one here in UK as they are not legal in competition play.

From a scientific point of view I guess it will work out the angle then make a simple ballistic calculation to either add or subtract some distance depending on whether the target is above or below the golfer.
 
You must log in or register to reply here.
Back
Top