User Review: Cammenga Tritium Lensatic / 3HC
Source: bought it new
Price Paid: $88
Well-made, but less than ideal for non-military users.
- Air-filled compass housing can't develop a bubble
- Self-luminous tritium lighting
- Excellent manufacturing and assembly quality
- Deep-well compass housing for multiple magnetic zones
- Mediocre accuracy
- Mediocre shock resistance
- Degree scale in 5-degree increments only
- Can fog over in certain conditions
- Compass dial slow to settle
The U.S. M-1950 dry lensatic compass currently made by Cammenga in the 3H configuration is lauded as being the toughest, most accurate compass on the market. After all, the U.S. military uses it, so it must be the best, right? Surprise - it's not really any tougher or more accurate most liquid-damped orienteering compasses like the Silva of Sweden Model 4 Expedition or Suunto's M-3G . Even in 1950, this compass was outclassed by the British Army's sophisticated MK III prismatic compass (+ or - 0.5 degree accuracy). And in the civilian world, things have changed a lot since then.
It's true that Cammenga's version of the M-1950 compass has a super-strong case and housing, and can't develop an air bubble since it's a dry card (induction dampening) design. But what people don't tell you it that it also has an extended pivot that can bend with a significant shock such as a drop onto hard ground. Once the pivot is bent, the dial will not produce repeatable, accurate readings. Note the official military 'shock' test — an easy 'drop test' of 90 cm (3 feet) onto a table covered with a 10cm (4-inch) layer of plastic-covered sand.
The M-1950 lensatic compass design is also frequently extolled for its superior accuracy over most orienteering-style compass designs in shooting an azimuth (taking a bearing) to an objective or landmark. Let's examine that.
The compass dial is in both mils and degrees, and as the military uses mils, the degree scale is given second place on the dial. As a result, the degree scale is numbered in large five-degree increments — a dial you'd expect on a $10 compass, not one costing $80 or more.
You can, if you practice, split the five-degree increment spacing in half to get a (theoretical) reading of 2.5 degrees between increments, while simultaneously holding the compass steady and the sighting wire fixed on the objective, then checking for parallax error — not easy. Or you could use the mils scale and convert each and every azimuth (bearing) you take back into degrees for the benefit of your companions (all of whom will have degree scale compasses).
But why bother, when other compasses have easy-to-read dials that can be read to 1 degree or less with ease? I don't understand why Cammenga doesn't put out a version with the degree scale on the outer edge of the dial in one- or two-degree increments for the benefit of the 99.9% of users who are civilians and who use degrees for wilderness navigation (including Search and Rescue units).
Besides that, there is the issue of inherent accuracy. Brand-new, the G.I. M-1950 lensatic is only required to achieve an inherent accuracy of + - 40 mils (2.25 degrees) from actual azimuth (milspec). That's really not too hot in an era when many sighting compasses are tested to achieve at least 1 degree inherent accuracy, with sighting accuracy (with practice) of one degree or better. Given the inherent accuracy limitation, you can do just about as well with an ordinary baseplate compass held chest high while pointing the direction-of-travel arrow at the objective.
Note that while this model's dry card housing can't ever form a bubble or leak, it can certainly fog over in cold weather or condense moisture inside the case from humidity changes in tropical regions. Why? Because the interior is filled with ordinary air instead of an inert gas like your fogproof binoculars or rifle scope.
The compass uses magnetic 'induction dampening' to settle the floating dial in 'six seconds or less'. Fine, except that in comparison, my liquid dampened Suunto compass with 'global needle' settles in less than one second, and stays rock-steady, with no wobble. Because the latter is a gimbaled design, I can even take accurate compass readings while walking or riding in a small boat or canoe.
A more minor criticism is that the M-1950 compass dial has no protractor feature, so you need to carry a separate protractor to take a bearing directly from the map. It has no romer scales, and only one 1:50,000 metric scale, which isn't much use for USGS 1:24,000 topos. It also has no adjustable declination feature for relating all compass headings to true north. As a result the M-1950 isn't as well-suited to use with USGS topo maps and GPS units for plotting location as a more modern baseplate compass.
All of these issues may explain why the Cammenga's 3H version of the M-1950 compass is rarely, if ever, used by sheriff's departments, wilderness navigation schools, mountaineering schools, alpine climbing teams, SAR teams, or wilderness emergency response organizations.
The compass itself is built with attention to detail and all parts on my example were well-fitted with no signs of manufacturing or assembly defects. Cammenga does an excellent job on meeting milspec standards.
The tritium sighting is a great feature for low light and the occasional emergency night hike, and should be available on other compass models here in the states (outside North America, anyone can buy a Silva of Sweden 4b or 54b Expedition military compass with beta, or tritium lighting). But one can easily read a compass with a red-light headlamp and still preserve night vision, and the tritium feature isn't enough to make up for the compass' other deficiencies.
In summary, the M-1950 lensatic compass in 3H configuration as made by Cammenga is a special-purpose military compass that needs a redesign to compete as a general-purpose wilderness navigation compass.