This review on the Vectronix Terrapin rangefinder is based on a 3 month long field test. It reflects the thoughts of 3 different precision rifle shooters as they used the product to observe and range hundreds of times. The full field test consisted of 8 different rangefinders, so we have a very wide view of what to expect in a good rangefinder. This post is compiled from our notes of what we specifically liked or didn’t like about the Vectronix Terrapin compared to the rest of the models out there.
- Extremely accurate and reliable
- Ranges small targets out to 1 mile in bright, midday light, and hillsides to almost 5,000 yards in ideal conditions
- Can range multiple objects with a single push of the button
- Very bright and crisp glass
- Etched, “always on” reticle makes ranging much easier than more common lit/temporary reticle
- Ergonomics seem ideal
- Built-in tripod adapter
- Great battery life
- 5x magnification seems underpowered for the ranging capabilities
- Repetition rate is slow, with a max of 12 ranges per minute. This makes you wait before you can do a follow-up reading.
- Doesn’t provide equivalent horizontal range (i.e. the distance gravity will act over)
- No ballistics functions
- Only a 1 year warranty … weak
A veteran USMC sniper told me he had a “man crush” on this rangefinder … and for good reason. Although the Terrapin isn’t the most expensive rangefinder you could buy, there is a strong case that it’s the best. Vectronix has been king of the rangefinder world for some time, and it doesn’t take long using one to figure out why. It practically always gives a range, even on relatively small targets at extreme distances … and the range it displays is surgically accurate. The Terrapins have very bright, crisp glass, that is outstanding in low light, but the 5x magnification seems like a mismatch for the extreme ranging capabilities of this unit.
Accuracy of the Vectronix Terrapin
At this year’s NRA Whittington Center’s Donor Appreciation Weekend, we met Earl Clark at the High Power Silhouette Range. We had several rangefinders out, and Earl asked what we were up to. After a little conversation, it turns out that Earl was one of the original surveyors for the NRA’s High Power Silhouette Range. He told us about how he and a group of experts used “transit equipment” (cutting edge surveying equipment at the time) to determine the range to the white buffalo, which is 1,123 yards. In fact, Earl showed us the exact spot they surveyed that distance from … a small X in the concrete near the center of the firing line that is still there.
What a find. Now we could see how accurate these rangefinders really were … the buffalo was not only a large target, and 1000+ yards is a good distance … we now knew the exact distance from an exact spot. I spent the next few minutes testing the rangefinders I had with me to see how close to the known 1,123 yards they would actually get. Here are the results from ranging the white buffalo several times with each rangefinder.
|Model||Avg Yardage Measured||Range of Yardages Measured*|
|Zeiss Victory RF||1,122||1,121 – 1,123|
|Leica Geovid HD-B||1,122||1,120 – 1,123|
|Leica Geovid HD||1,121||1,120 – 1,125|
|Actual Surveyed Distance||1,123||1,123|
*The range of yardages measures represents the “extreme spread” of the distances displayed for each model. For example, the Leica Geovid HD showed distance measurements from 1,120 yards to 1,125 yards and everything in between. The amazing thing is the Vectronix Terrapin would only display one distance no matter how many times we tried … the correct one, exactly 1,123 yards.
The Vectronix Terrapin ranging performance is ridiculously good. Although my tests were primarily focused on relatively small targets from 600 to 2,000 yards … they could certainly stretch out beyond that on larger targets. In fact, in ideal, low-light conditions I was able to consistently get readings to almost 5,000 yards across a wide canyon at our range.
Here are the results of ranging a 2 MOA reflective target in ideal, low-light conditions from a tripod at ranges from 600 to 2,000 yards. The exact size and shape of the targets, as well as the surroundings varied, but details of each target along with more details of the test are given in the ranging performance test results post. Each target was ranged 10 times under the same conditions.
This is ridiculous performance. Out of the 80 readings that are represented in the chart above, the Vectronix Terrapin never once displayed an incorrect reading. Any distance it displayed was at least within 1% of the actual distance, and the average standard deviation among all of those ranges was 0.8 yards which was also the best of any rangefinder tested … by far (the next best was over 3 yards). It only gave a “no read” twice in those 80 attempts, which is only 2.5% and well within the margin of error for that sample size. That just means it happened so infrequently that it could’ve been from an error in my testing as much as an error in the rangefinder itself.
Keep in mind that the Terrapin may have been able to range targets beyond 2,000 yards in ideal, low-light conditions (i.e. sunset) … but that was simply the max distance I had targets set at my range.
Just look how the ranging accuracy of the Vectronix Terrapins stacked up among some other rangefinders tested at the same time. The diagram below shows how accurate each model was at ranging targets from 600 yards to the maximum range each one was able to give a reading for. They were about as perfect as you could possibly expect.
In bright light conditions, radiation from the sun can cause interference and limit the range and resolution of readings a rangefinder is able to gather. This obviously has a negative effect on performance. The chart below shows how the Vectronix Terrapin performed at sunset, which is ideal, low lighting conditions, and how it performed ranging those same targets in bright, midday lighting conditions. Once again, this testing was done from a tripod, with visibility of 10+ miles on 2 MOA, reflective targets.
In bright conditions, the Vectronix Terrapin could only range the 2 MOA targets to 1 mile (1760 yards). It didn’t give me a single reading on the targets at 1,950 yards or 2,000 yards in bright, mid-day conditions. However, it did give me readings on the 1 mile target 90% of the time and they were very accurate readings (as you might have guessed by now).
Although my field test was primarily focused on ranging binoculars, none of them could keep up with the ranging performance of the Vectronix Terrapin. The Vectronix Vector 23 was outstanding, but I can’t say they performed any better than the Terrapins inside of 1 mile (1,760 yards). Honestly, if I knew my life was on the line to make a single shot and I had a spread of every rangefinder possible in front of me to pick from, I’d definitely reach for the Vectronix Terrapins. After taking 10,000 measurements with all kinds of different rangefinders, I have more confidence in the Terrapins than any other pair.
The Terrapin’s beam divergence (2.4 × 0.4 mrad) seems ideal for relatively small targets at 2,000 yards or less. I know a lot of guys think the tighter the beam the better, but the main objective is to get adequate energy on the target … without missing the target. The diagram below shows an example where having really tight beam divergence could hurt performance.
So you could have a beam divergence that is too large or too small. It is all about striking the right balance between the two extremes, and it comes down to the size of your typical target and the typical range. While the Vector 23 has a tiny beam divergence, that is primarily because it was designed to range well beyond 10 miles. The beam divergence of the Vectronix Terrapin seems to strike the right balance for relatively small (2 MOA targets, or typical game-sized animals) at realistic ranges you might actually shoot out (around 2000 yards or less).
I also tested the Vectronix Terrapins offhand, meaning it wasn’t supported by a tripod. I had larger sample sizes here because of the natural loss of pinpoint accuracy when you range offhand. I also ranged slightly larger targets (2’ x 3’ white boards) at both 600 and 800 yards. Each was ranged 20 times, and was done by 2 different people to try to level out any bias in technique. The results are shown in the diagram below.
Although that may not seem impressive, one huge benefit is that the Vectronix Terrapins didn’t give a single “no read.” Every other brand at least gave a few, but the Vectronix models displays a range every time. You can see the scatter of the Vector 23 model was more dispersed and that is due to the tighter beam divergence. Essentially, it was easier to accidentally miss the target if you had slight wobble, like I was referring to earlier. The Terrapins had amazing accuracy on the 800 yard target, which was a little different scenario than the 600. The 600 yard target had some brush immediately in front of it, that wasn’t obscuring the target … but did likely reflect some beam energy that caused the Terrapins to occasionally display that distance. The 800 yard target was out in the middle of the open, but had brush directly behind it that reflected some energy. The Terrapins weren’t as easily tricked in that scenario, and only had a few readings on the background brush at 800 yards.
The Terrapins don’t offer any ballistics functions. Also, unlike the Vectors they don’t have a built-in compass, which was true for most rangefinders.
Equivalent Horizontal Distance
The Terrapins don’t provide functionality to display the equivalent horizontal distance. As a long-range shooter, this is an important feature because that is really the only distance measurement I care about. This measurement goes by many names, Bushnell calls it “Angle Range Compensated distance,” and Leupold calls it “True Ballistic Range.” Regardless of the name, this measurement essentially displays the distance that gravity will act over, not just the line of sight distance. It is really only important on extreme angle shots, but I prefer to always stay in that mode because that is the distance you should type into your ballistic calculator or lookup on your dope card. It’s not a disaster that the Terrapins don’t provide this feature, but it would be cooler if it did.
Advanced Ranging Features
Vectronix has an innovative feature on all of their rangefinders called “Multiple Object Measurement” (also known as “3 DIS”) that you could enable to make it show the top 3 readings from a single measurement. When this is enabled, it will automatically highlight the distance it thought you were intending to range, but also shows you the second and third strongest readings received as well. For example, if you were ranging a tree at 250 yards, and 100 yards behind it was a jeep, and 1000 yards behind that was a building … it would display 250, 350, and 1350 (and probably highlight the 350 yard reading).
When talking to a rep from Vectronix about my post on how rangefinders work, he told me “like you said, the logic of what to display to the user is what’s truly important and that’s why all of our laser rangefinders have Multiple Object Measurement (also known as 3 Dist) to ensure the real range information is available to the user.” Most manufacturers just pick a distance and display that, and don’t provide a way for the user to explore the underlying data beyond that single reading. That is a bad approach, because the computer can’t possibly know as much as you do about the ranging scenario. I’m not saying display all the distances detected, but it would be ideal if manufacturers allowed you to drill down into more details about the underlying data the rangefinder was able to gather, instead of hoping all you need is the one number it picked to show you.
Most of the rangefinder binoculars I’ve used have an electronic reticle that appears when you pressed the button. However, the Vectronix models have an engraved, “always on” reticle that makes aiming and ranging a little easier. The reticle is also mil-based, which is handy if spotting for another shooter.
In the related field test, I did test the optical quality of the Terrapins but it is definitely handicapped when compared to binoculars with 10x magnification. The Terrapin is a monocular, and only has 5x magnification. That is actually one of my biggest complaints about this unit. It feels like the 5x magnification is a mismatch for the ranging capabilities of this unit. You can range really far, but you just can’t see really far (at least not with as much precision as I’d like).
After using the Terrapins for a few weeks, one of the testers thought they might ditch their binoculars and just start carrying the Terrapins for observation and ranging. It seemed like a plausible idea. The problem is the magnification on those units just isn’t enough to be able to locate targets or game in some situations. On our range, we have an unknown distance target field where we move the targets around a lot. My friends was using the Terrapins to locate and range targets, and thought he’d found them all. However, when he raised up his binoculars to double-check he immediately saw a target that he had completely overlooked with the Terrapins. It was obvious with the 10x binoculars, but he hadn’t noticed it with the 5x monocular.
Don’t get me wrong, the Vectronix glass in this unit is certainly world-class … it just doesn’t have enough magnification to use them as your primary optic in the field situations I find myself in regularly.
For my field tests, I tried to come up with an objective, data-driven approach for testing optical clarity and what I ended up doing was placing eye exam charts from 600 to 1,400 yards and then recording what size of letters two different people could accurately read. These were virtually identical to the eye charts doctors use to assess visual acuity by determining how much detail and definition a patient can make out at a particular distance. I combined all that data into a single score for each model so they can be ranked in terms of how much detail my two testers could make out. I provide a lot more detail about how the test was conducted, and compare other optical specs in The Optical Performance Results post.
Keep in mind there was no handicap awarded for having a lower magnification or being a monocular instead of a binocular. We just took each unit and wrote down what we could accurately see (which seems fair and appropriate … you don’t get a handicap in the field).
You can see we weren’t able to see near the amount of detail with the 5x monocular that we could with more standard 10x binoculars. This isn’t surprising, but it helps illustrate the point that I was trying to make on not being able to see the same amount of detail with 5x magnification … regardless of how good the glass is.
One major benefit of low magnification is a super-wide field of view. You can see in the chart below that the Terrapins had the widest field of view by a large margin. The Leupold RX-1000i was also a monocular with just 6x magnification and look how much better the Terrapins performed over that model. Vectronix definitely maximized the field of view on these models, and that is likely what drove the decision for the lower magnification.
The relative brightness of the Terrapins was also much higher than most other models tested. That is because the Terrapins have an exit pupil of 4.8mm, which is larger than most binoculars or monoculars. The exit pupil is the size of the circle of light coming out of the eyepiece of the optics. The bigger that circle of light is … the brighter the image (at least to a certain point). Binoculars.com says “This index reminds us that as the size of the exit pupil increases, its area and ability to transmit light grow geometrically.” If the relative brightness value is below 15, the optics will likely struggle in anything but bright light. If relative brightness is over 25 it will likely be exceptional in low light conditions. The Terrapins had a relative brightness of 23, so they would like perform better than most optics in low light conditions.
The ergonomics of the Terrapins were great overall. They have a built-in tripod adapter, which is very handy. They also feature a very large ranging button with a positive click when you push it, which makes them easier to operate. The standard rectangle box shape makes they easy to hold and feel natural.
The eyepiece cup works well, but since it wasn’t a standard roll-up/down eye piece like most binoculars it made it virtually impossible to mount any type of digiscoping equipment to the eye piece. That’s okay though, because I might be the only guy who ever tried to do that!
They come with a very basic, thin lanyard, which some people might like. Others might prefer a more substantial neoprene neck strap, but the Terrapins only weigh 18.6 ounces … so they are very lightweight.
One of the biggest benefits was the compactness of the Terrapins. They measured 5.4” × 4.1” × 2.1”, which isn’t the smallest “pocket rangefinder” … but is much smaller than most binoculars. But since they are the Vectronix Terrapin PLRF, which stands for Pocket Laser Range Finders … you’d expect them to be small. In fact, Vectronix says they are “the smallest and lightest MIL-SPEC rangefinders available.
They do feel extremely solid and rugged. They are truly MIL-SPEC, and carried by many militaries around the world.
Most manufactures make it very tough to compare their product to others out there. So, I spent days searching websites, user manuals, and calling/emailing manufacturers (several times each) to gather a complete set of detailed specifications and put them in a format that allows easy side-by-side comparison. There are almost 40 different specs, including actual measured weights, dimensions, and the max ranges found in my field tests for each model (which can be very different from what the manufacturer claims). Some manufacturers list this specs in metric units and others are in U.S. standard units … I’ve converted everything to the same units to make comparison easy. I also read through each of the manuals to see exactly what each one does or doesn’t have in terms of advanced features like equivalent horizontal range, and ballistics functions. Some of the specs I even measured or calculated myself, because they weren’t available anywhere or were specs manufacturers are notorious for exaggerating.
|Manufacturer Part #||909207|
|Measured Weight in Use²||18.6 oz|
|Measured Dimensions³||5.4 × 4.1 × 2.1 inches|
|Tripod Adaptable||Yes, Built-In|
|Included Strap||Small Lanyard|
|Limited Warranty||1 yr, Non-transferrable|
|Beam Divergence||2.4 × 0.4 mrad|
|Tested Max Range⁴||4,947 yd|
Claimed: 2,624 yd
|Tested Min Range||6 yd|
Claimed: 22 yd
|Claimed Accuracy||± 3 yd|
|Tested Repetition Rate||12 Ranges/min|
|Receiver Optic (Rx) Aperture Size||24 mm|
|Laser Type||905 nm|
|Pulse Duration||MFR refused to specify|
|Battery Type||2 CR123 Lithium|
|Battery Life||7,000 measurements|
|Equivalent Horizontal Range Function||No|
|Display Multiple Object Distances Function||Yes|
|Advanced Ranging Modes||Multiple Objects|
|Objective Lens Diameter||24 mm|
|Exit pupil||4.8 mm|
|Eye Relief||20 mm|
|Field of view at 1000 yards||426 ft|
|Objective Angle of View||8°|
|Prism Type||MFR refused to specify|
|Glass||MFR refused to specify|
|Coatings||MFR refused to specify|
|Relative Brightness (RE)||23.0|
I expected a military-grade warranty with the Terrapins, but they only come with a 1 year limited warranty. And the warranty is non-transferrable, which means only the original owner is covered by the warranty. That is weak, considering Leica offers a 5 year warranty and Zeiss even tops that with a lifetime, transferrable warranty. But, since these are military-grade, they might last far longer than those other brands … they definitely out perform them in the field.