A range finder, even a primitive range finder, is based on the exact same principles which are employed to manufacturer auto-focus cameras. They work like this: The camera emits an invisible laser beam of light which hits the subject object, then reflects back to the camera, where a sensor detects the beam, and transfers the data to a computer chip. The chip calculates the time it took for the beam to return to the sensor which determines the distance the subject is, and automatically adjusts the camera’s lenses to that specific distance.
Laser range finders operate under the exact principles. An infrared laser beam is emitted from the rangefinder, hits the target and rebounds back to the rangefinder. A computer chip analyzes the information and translates it into distance. This entire sequence occurs in seconds and is accurate, even with less expensive models, of plus or minus 1 yard/meter. There are models available, military grade, that are accurate to mere inches.
As with everything else we buy, quality and cost plays a big role in our choice, therefore it’s important to know the differences between range finders. All consumer range finders use a class 1 laser, the difference between a rangefinder rated a 300 yard maximum and one that rates 1200 yard maximum, is the computer chip and sensor. The more complex the internals, detecting lower light, filter out false information, quicker readings, etc. the more expensive. Know what and where you’ll likely be hunting and make your decision based on those issues. For instance, a 300 yard maximum rangefinder, for all practical purposes, would be useless hunting the large valleys of Montana, where a 1000 yard shot is not unheard of. Buyer beware:There are an incredible amount of variables involved in calculating maximum range. So many in fact that some manufacturers have stopped displaying maximum range on their advertising. That doesn’t mean the LRF won’t correctly display a 1000 yard distance, it’s just not likely to be perfectly precise in real life performance.
Bow Mounted LRF
It may come as surprise to some, but lack of knowledge or skill of the user is the number one (1) reason a LRF will give off a false reading. After buying a new LRF take time to get to understand it. They are, at first, quite complicated with different functions for bow hunting or rifle hunting, rain or fog mode, scan mode, etc. May I dare suggest you may even try reading the instructions.
Again a LRF operates on a “Time-of-Flight” technology, emitting a laser beam and capturing its return reflection, allowing a microprocessor to convert turnaround time into yardage. However, no matter how smart this microprocessor is, it isn’t smart enough to determine if what you’re aiming at is actually what you intend to aim at. That’s where a little human common sense must be utilized. If you’re trying to gauge the distance to a deer in the valley and you get a 25 yard distance reading, you have obviously scanned an obstruction must closer, not the deer. However, when bow hunting a mistake like that could be easy to make. The deer may be 30 yards away, but you receive a 24 yard reading, because you’ve identified a branch between you and the prey, it’s not as glaring of a discrepancy and often leads to missed shots.
To hold a steady cross-hair on a deer with a LRF is no easier than holding one with your scope/rifle combo, and probably harder because it’s lighter. If you can’t hold a steady aim long enough to get an accurate reading, the most expensive LRF is no better than the cheapest. One trick to use, animals rarely stay perfectly still, making a perfect reading difficult … pick out an object, say a large rock or tree that’s adjacent to the target. You’ll get an accurate reading from that stationary target that you will translate into your scope reading.
Different Modes and Options:
Similar to a motor vehicle not all LRF are equipped the same. There are different modes (options) for different conditions. Check these out to know what you’re buying. Don’t wait until you spot a possible target to realize you don’t have a mode you thought you did.
Angles: There’s a big difference between straight line shooting and vertical compensated range. This effects bow hunters more than rifle hunters as most bow hunters shoot from elevated stands or on high steep ground. If the bow hunter uses the straight line reading provided by the laser rangefinder, it will result in a high shot and probable miss. This is the result of geometry, actual distances, angles and heights, just about everything I don’t understand. Luckily the manufacturers have addressed this problem with an accurate tilt-compensated rangefinder, but not all models are equipped with this mode. Not a huge mistake if you are a rifle hunter, a possible catastrophic error if a bow hunter.
Scan Mode: Its designed to give you a running measurement of a moving target, such as meandering while grazing, not a full out sprint, but can also be used to obtain a somewhat accurate reading through patchy vegetation. You scan back and forth in the direction of the target, pan until your laser beam breaks through a clear spot. These multiple pings are quicker than trying to get a single beam on the target through dense brush.
Brush, zip mode: This mode is generated by a filter that tells LRF to ignore brush between you and the target, which it does by focusing on the farthest object while ignoring closer ones. This is a must have for anyone who hunts in the woods, and is the default setting on many rangefinders.
Professional Grade: I’m not saying nobody buys or needs to buy a professional grade LRF, but unless you’re a competition shooter or a military sniper you won’t be able to use it. Why? Allow me to explain.
The instant your bullet leaves the muzzle of the firearm it begins to drop. There are LRF models that come equipped with a ballistics program, that you program variables into, such as load, cartridge, zeroing procedures, and it will calculate the amount of drop for the specific distance. This tells you how much of a hold over or hold under to employ. As you can see it is very complex and very expensive, but I thought I’d make you aware of such a devise.
Environmental Obstruction: Primitive Range Finder
I know I keep returning to the basics, but everything builds off the basics. The principal of a laser rangefinder is to emit a beam of light to get a reading off an intended target. Therefore, it’s important to remember anything that affects the operation of the beam influences the reading as much as the reflective ability of the target.
Any environmental factor which slows down or disperses the beam of light will affect the quality of the reading given by the LRF. The speed of light is derived inside a vacuum, therefore if anything voids that vacuum, it affects the accuracy of the reading. For instance, light travels quicker through lighter air than dense air. Fog, moisture, elevation or snow will retard speed. Usually this issue is not a big deal, but heavy rain, snow or fog can render a RLF useless as the light beam can not penetrate the elements.
Tip: While I’m thinking about it. Be sure to buy a waterproof LRF, or waterproof it yourself if its not. Moisture is a mortal enemy to sensors and microchips, as well as dust and dirt. Using a non-water proof LRF in the outdoors exposed to the elements will result in premature failure.
Maintain Your Human Skills: Primitive Range Finder
You won’t realize it until its too late, but by relying on a rangefinder you will lose your once, somewhat accurate, yardage judging skills. This can result in a ruined hunt if the batteries on your LRF die while in the woods. Retain these skills and become much more skilled with your LRF by killing two birds with one stone. Take your dog for a walk and every so often stop and pick out a target and estimate its distance from you. Then double check your estimate with your LRF.
Remember, nobody can take a skill learned away from you. Only you can do that by not keeping it sharp. The old saying “Use it … or lose it.” Applies here.