How Does a Rangefinder Work?

Being properly equipped while in the field is an essential component to embracing the hunt. Like a soldier properly equipped on the field of battle so is the hunter in his stand. Yes, a proper shot can be taken without a rangefinder, but the consistency of accuracy could rarely ever be matched.

Simply put, it is an abnormality to be able to accurately predict the distance of targets that are 300, 400, or even 1000 yards away. Try as we will, our attempts at hitting our target with our first shot often come up short or stray overhead.

At this point, we can begin to adjust our shot based on a previously missed attempt.

Unfortunately, one-shot is often all we have as we see our prize winning buck scurrying off in the thick brush. For any of you who have experienced this challenge or for those of you who want to avoid it, a rangefinder can help.

Some of you may already own a rangefinder and simply want to know how it works. Others of you may be wondering if it is a good idea to make an investment in what could potentially be a large purchase. Either way, I hope to bring some clarity on a scientifically-complex product that is simple in its use.

How does a OPTICAL rangefinder work?

The optical or mechanical rangefinder produces an accurate reading on a target by producing two images of your desired object. says, “The device then merges the two images together. When this happens, the distance is read off the scale on the adjustment control.”

How does a RADAR rangefinder work?

A RADAR rangefinder works by sending out radio waves rather than a laser to its target. These radio waves then bounce off the target and return to the rangefinder. At this point, the device is able to determine the distance based on the time it took for the waves to leave and return to the rangefinder.

How does a SONAR rangefinder work?

A SONAR rangefinder works by sending out sound waves that move at the speed of sound to the target then back to the device. When the sound waves return, the rangefinder calculates the distance based on the time it took the waves to leave and return to the device.

How does a LIDAR rangefinder work?

The LIDAR is somewhat similar to the laser rangefinder and uses projected light that is shot at the target then bounces back to the rangefinder to measure distance.

How does an ultrasonic rangefinder work?

The ultrasonic rangefinder is another rangefinder that works by projecting sound waves to a target then calculating a distance upon their return to the device.

How does a laser rangefinder work?

I have saved the bulk of this article to devote to the use and function of the laser rangefinder as it is by far the most popular choice and currently the most practical. It will also be the most beneficial choice for hunters of all ages and skill levels for anything from practicality to ease of use to price.

The laser rangefinder is relatively new. says, “Advances in laser technology led to the development in 1965 of another kind of ranging instrument known as the laser range finder.” Manufacturers of the laser rangefinder continue to develop this into an amazing piece of equipment.

A laser rangefinder, as the class name states, functions by using a laser to accurately determine the distance of a target. With the push of a button, a tightly condensed cluster of laser beams, that is invisible to the naked eye, travels at the speed of light until they reach an object that stops its progress. says, “[A]n infrared laser beam (invisible) from your device hits your desired subject and reflects right back to the device.” Built into the equipment is a device that is able to determine the time that it took for the beam to hit the target and return.

After the laser returns, the internal system uses a mathematical equation to determine the distance to your target.

For a quick and helpful resource in understanding the basics of a laser rangefinder, check out the following video:

The differences between reflection and deflection

While the rangefinder is a great product that will prove to help on the field, like anything else, it is not a perfect product. Understanding the differences between reflection and deflection can be helpful in developing an overall picture of how the rangefinder works.

When the laser projects from the device, it will travel until it hits an object. The vast majority of objects will cause the laser to bounce back to the device and give you a distance reading. This is known as reflection.

However, in some instances, the object that the laser hits, rather than reflecting back to the device will deflect away. In the event that an object is angled severely away, it could be difficult to gain a proper read as the beams may deflect away. However, this would not be the norm.

First priority

In seeking to understand the way in which a laser rangefinder works, it is important to know that each rangefinder is built with a primary focus in mind. What I mean is that laser rangefinders are either built with a first or second priority function.

Why this is important to you is because, for those of you who like to hunt with either rifle or bow, you do not want to purchase a first priority rangefinder. These rangefinders are more adept for the golfer.

The reason for this is that first priority rangefinders will reflect the laser light off the first object it hits and gain a read based on that. While golfing, there usually won’t be much to get in the way of the golfer and the hole.

However, there are often plenty of trees, brush, water, grass, etc. behind the hole. The device will not gain a read on all of this other stuff off in the distance.

Second priority

For the different types of hunting and even for the surveyor, the second priority mode rangefinder is a good choice. The reason for this is that, as was stated earlier, when you push the button on your rangefinder to gain a read on a target, this will shoot out a cluster of tightly condensed laser beams.

When these laser beams project from your device, they will have a tendency to encounter a number of different objects on the way to your target. While a deer may be off in the distance, along the way the beams may hit a branch of a tree, a portion of a rock, or the tip of a leaf.

As all of these different objects are hit along the way to your target, they will cause the laser to bounce back to your device. As you know, you are not concerned about the proper reading of these, but rather the deer that is behind them all.

The second priority mode rangefinders are built to factor all of this into play. Steven L. at says, “A hunting rangefinder, or second priority rangefinder would ignore the first object in its line of view such as the branches, and read the most distant object, which may be a deer.”

As a side note, there are a number of rangefinders that come with the ability to toggle between first and second priority mode.

Scan mode

A number of rangefinders have a built-in option to scan for your target downrange. This is a great option and will prove to make getting an accurate read easier on anything from one target that is standing still, to a moving target, to multiple targets.

This mode will vary from rangefinder to rangefinder, but simply put, hold the button down for a length of time while you move the device’s reticles over your target(s). This will produce your desired read(s) on your target.

Lens adjustment

For any of you who have ever used binoculars before, adjusting to a rangefinder won’t be much of a stretch. The word binocular has the prefix bi meaning two. Hence these devices have two lenses that you can look through and magnify desired objects.

In the case of binoculars, as most of you are probably well aware of, the two lenses have attachments to their lenses that can be twisted to the left or the right. When twisting these lenses, you can probably remember that this allows you to focus in better on the object that you want to see.

The rangefinder works in the same way, but unlike a set of binoculars, the device is a monocular device (the prefix mono meaning one). This one lens has focusing capabilities that can be adjusted by simply twisting the lens attachments.

How does a rangefinder reticle work?

For any of you who have ever used a scope on a rifle before, understanding the purpose and use of the rangefinder’s reticles will be second nature. However, for those of you who have not used a scope, the simplicity of the device’s use will soon shine forth.

In the case of a scope on a rifle, the reticles can be turned on with the push of a button. At this point, you stick your rifle in your shoulder, look down your scope, put the reticles on your target (I know this may vary for distance), and pull the trigger.

When using your rangefinder, you will use it in a similar fashion. The major difference is that you do not want to aim above your target. All you need to do is push a button and turn on the reticles.

After turning on the reticles, Dick’s Sporting Goods says, “Once you’ve found and put your crosshairs on target, … push the measure button once more.” This will give you a proper read on your target.

What about various terrain features?

Another great benefit of owning a rangefinder is that the device is able to factor in various features in the terrain. says, “When you’re on a decline or incline, your target not only looks further away but is in real sense further away from the actual distance you want to aim.”

Determining a proper distance to your target in such conditions can prove to be extremely difficult, and even stressful at times, as yet again your arrow strays off into the distance and you miss your opportunity.

A rangefinder will come with the ability to determine proper readings based on the various features and contours of the earth’s surface. Mountains, hills, slopes, ravines, plains, and valleys will all be terrain that the rangefinder will help you to get the upper hand on.

What is the maximum range of a rangefinder?

The maximum ranges for the various rangefinders vary greatly. On the bottom end, anywhere from around a few hundred yards for a maximum range is a popular choice. On the top end, upwards of around a couple thousand yards is a popular choice for long-range hunters. says, “If you know you’re only going to use it for closer distances of 200-300 yards, then you might not need to prioritize this so much. On the other hand, if you want to range a deer at 1,000 yards, you’ll need to ensure you get a rangefinder that can accurately measure at that distance.”

Concluding thoughts

Rangefinders can be found with different built-in mechanisms to determine the distance to a target. In large part they work by sending something out if it, and this light, sound, etc. then bounces back to give a proper reading.

While the rangefinder is a relatively new product, its popularity is steadily increasing. However, developing an understanding of its use is important in determining its personal value. This scientifically-complex device that’s simple in its use may be the piece of equipment that you’ve been missing.

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