Some of the most expensive rangefinders available today aren't accurate enough to be functional for bowhunters.
Let me explain: Let's say a rangefinder is off by three yards. If you're a rifle hunter, it really doesn't matter if your rangefinder tells you the distance is 200 yards when the distance is actually 203 yards. You'll still hit the deer in the vitals.
However, if you're a bowhunter and your rangefinder reads 50 yards when the actual distance is 53 yards, you might be in trouble.
This is especially true if you are using a less-than-speedy bow. Theoretically, under the circumstances just described, you could miss the mark by as much as seven inches at 50 yards — even if you make a perfect shot.
However, if you happen to bobble low at the instant of the shot, you could completely miss a deer-sized target.
Because there are so many more rifle hunters than bowhunters, most manufacturers design their rangefinding products with firearm hunters in mind. This is where bowhunters often get short changed.
The Smaller Your Variables, the Better
I always harp on the fact that you need to make sure everything within your control is as close to perfect as you can make it. All tolerances should be as tight as possible.
Mechanical engineers have a term they use to describe what happens when you have an additive effect of imperfections. They call it "stacking tolerances."
The following is an illustration of the general principle they are describing as it relates to bowhunting: Let's say you are shooting at a deer.
If you happen to be aiming a little low when the shot breaks — and the arrow you are shooting happens to be the one that consistently hits low and you are pulling too hard into the stops (which causes you to hit low) — you are going to miss badly if your rangefinder reads low.
If each of these tolerances is large, and they happen to align perfectly for that one shot, the miss will be huge. However, if each of these tolerances is very tight — even if they do all happen to align — the miss will be small.
The smaller each of these variables happens to be, the less likely you are to have a substantial miss. My point is that you want your variables to be small, so you must be a stickler when it comes to every detail of form and equipment.
When it comes to yardage and sighting in, I try to be as precise as possible. I measure the distance to each of the targets on my range with a steel tape. My 20-, 30-, 40- and 50-yard marks are exactly right, and I've got a stake pounded into the ground at each of these 10-yard increments.
Sighting in at this range works great for me when I am preparing for a marked yardage tournament because the targets at the tournament are all measured with a steel tape as well.
At one time or another I have tested just about every brand and model of rangefinder available on this course. The performance of some of these rangefinders has been very disappointing. The worst of these rangefinders will be off by up to three yards from the actual measured distance.
To further complicate matters, these rangefinders may be reading the distance as being either too long or too short. That's a potential six-yard swing from one rangefinder to another!
Just to be clear, each individual rangefinder will usually be consistent — meaning it will read consistently too short or consistently too long. The problem comes when you start relying on different rangefinders at different times.
Another potential problem is sighting in using the marked yardage at the range and then relying on your rangefinder while hunting.
Beware of Conversions
Some of these rangefinders were originally designed in Europe and were meant to be used in meters. In order to sell to the American market, they merely programmed each unit to read the range in meters and then convert meters to yards.
There is an inherent problem with that system that I can't fully outline here. The important thing is to know that these rangefinders will actually skip certain yardages altogether and be off by a considerable margin at other distances.
These devices might read one yardage — say 43 yards — and if you move up an inch at a time until it transitions to the next reading, it will read 45 yards instead of 44 yards. These rangefinders can be off by as much as a yard or two at any given distance. The inaccuracy is built into the conversion system.
A year or so ago, I bought a very expensive rangefinder binocular. It would not read any yardage under 35 yards. I was extremely disappointed. This was another example of a manufacturer ignoring the needs of bowhunters.
Bottom line? Buy a rangefinder that is accurate. Test it against measured distances. Then, always sight in using the same rangefinder you will be using in the field. For full disclosure, it actually doesn't matter if your rangefinder reads the true distance as long as you sight in using that rangefinder.
When you are practicing in camp, don't just shoot where your buddy is shooting for 60 yards — you must shoot where your rangefinder determines 60 yards is. Along the same lines, if you ever have a guide or hunting buddy calling ranges for you while hunting, make him use your rangefinder. Don't let him use his own.