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| Leupold's Laser Rangefinders
Leupold RX Series Laser Rangefinders
I’ve long been interested in getting a laser range finder. What with shooting, hunting and battlefield touring I could see a lot of potential use for a toy like that. These devices work by bouncing an invisible laser off of the target and either timing how long it takes to make the round trip or detecting a phase change in the signal. The details are a little too deep for me to write about!
The accuracy of the measurement is dependent on the reflectivity of the target and the atmospheric conditions at the time (read that rain, fog, smoke, etc.). A bright colored target bounces a stronger signal back than a dark one. Fog or rain weakens the signal by dissipating the laser light. Those are a couple of factors to keep in mind when you’re using them.
One drawback I’ve seen on all of the laser rangefinders around up to now is that they only give you the Line-of-sight (LOS) distance to the target. If you are shooting up or down at a steep angle this can be misleading. If you remember your geometry you see that you are using the hypotenuse measurement of a right triangle while what you really need is the true horizontal or base measurement from you to the target. Gravity only acts on the bullet for this horizontal distance. For example, if the LOS measurement is 400 yards and the target is at an angle of 40 degrees above or below you the horizontal distance between you is actually 335 yards. If you held for 400 yards you’d shoot high.
So, what does all this have to do with anything? If you use a laser rangefinder and you need to know the actual “shooting distance” to your target you have a couple of options. You could carry the rangefinder, an inclinometer and a calculator, and then calculate the correct distance to your target. Or you can buy one of the new Leupold RX Series rangefinders and let it figure it for you. Leupold calls it the “True Ballistic Range” or TBR for short. It’s just what the doctor ordered, especially for anyone hunting in mountainous terrain.
There are four models in the RX Series. All have a focusing eyepiece, choice of 13 different reticles, built in thermometer, Yards/Feet/Meters mode, scan mode and LOS measurement. The RX-I and RX-II have 6X magnification and are “weatherproof” while the RX-III and RX-IV have 8X magnification and are “waterproof”. The RX-I is the entry level model, lacking a number of the bells and whistles the other models have, including the TBR. Starting with the RX-II the TBR is a standard feature. Other features, as you go up in model, include “Rain mode”, digital compass and various targeting modes.
While wandering through Bass Pro Shop a while back I saw an RX-III in the display cabinet. The price was $400. This model has all the features except the built in compass. It is 4.6” x 3.5” x 2” and weighs 12 ounces. The battery life is 2000 activations. The useful range is from 3 to 1200 yards. You should note that 1200 yards is the maximum range using a reflective target. The instructions say that for a deer type target the maximum effective range is 500 yards. Since I had some gift cards I just HAD to use I felt it necessary to purchase it. At least that’s what I told my wife…
One of the wonders of modern electronics is that they have LOTS of features and options to choose from. That sure can make them a pain to set up! The Leupold uses a “Quick Set Rotary Menu” to allow you to scroll through the options. Choosing some options turns off others so make sure you read the instructions.
A list of features for the RX-III follows:
Match 13 Reticle System – Choice of 13 different reticles.
Long range mode – ON or OFF. ON only reads objects over 150 yards away.
Rain mode – ON or OFF. ON helps prevent false readings due to rain, fog, etc.
1st Target mode OR Last Target mode OR neither. See explanation below.
Yards OR Feet OR Meters reading.
Fahrenheit OR Celsius OR LOS reading.
TBR – ON or OFF. Also activates the inclinometer reading.
Ballistic Group Selection – A, B, C, AB, AC, BC and ABC. Offers a choice of eight groups of cartridges/loads for use with the TBR. The groups are listed in the instructions.
I set the unit to show measurements in yards. I naturally selected TBR mode and also have it show LOS and the angle of inclination in the lower right hand section of the display. Another option is the selection between “1ST Target Mode” and “Last Target Mode”. If there are several objects in view the rangefinder can sometimes give you an average distance for all of them. “1ST Target” gives you the range to the closest target and ignores anything in the background. “Last Target” ignores the fore ground and gives you the distance to the farthest target. I’ve initially set mine for “Last Target” thinking that while hunting I’ll probably have to range through light brush, trees, etc.
You can select which information you want the TBR to display. Your choices are BAS, MOA or HOLD. BAS is the actual horizontal distance to the target. To use HOLD or MOA you have to specify a “ballistic group” of cartridges and zero your rifle at a specific distance, explained in the instructions. For example: a .280 Remington with a 140 grain bullet at 2990 fps would fall into ballistic group “C” and would be zeroed at 200 yards. Then HOLD will give you the inches of holdover/under and MOA will show the minutes of angle for holdover/under. Since I plan to use this thing with a number of different guns I chose the BAS mode.
The rangefinder couldn’t be much easier to use after you’ve set it up. Look through the eyepiece at the object you want to measure and press and hold the power button. A reticle will appear to help you line up on the target. Center the object in the reticle. The display mode and the distance will start blinking over the reticle. Release the power button and the distance will be displayed for a few seconds. The display can also be lit by pushing the “SET” button. Then the unit will power down to save the battery.
At this time I’ve only done some limited testing. I measured some distances around the house; to neighbors’ houses, mail boxes and such. I also took the device to the range and measured some known distances and the measurements were dead on. One of the first things I noticed is that it’s hard to hold steady on a small target at any great distance. The unit has a threaded hole in the bottom for a support such as a monopod or tripod. If I was going to try to use it on distant groundhogs or prairie dogs I’d keep that in mind.
So far I’m pleased with my purchase. When deer season gets here I’ll use it for determining the distances of certain landmarks from my stand locations. If I know that a certain tree, for example, is 130 yards from the stand it will help me place my shot better when that deer wanders by. Of course, if time permits, I’ll be able to measure the distance to any deer seen directly. Some time next year I hope to use the rangefinder on a trip to Gettysburg. Just exactly how far is it from the “sniper’s den” at Devils Den to the top of Little Round Top?
Posted by Pumpkinslinger on Sunday, October 07, 2007 (17:07:19) (9630 reads) [ Administration ]
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