Laser rangefinder Lomvum LV 66U at 40m with a digital protractor and an inverted screen.

Hello!
In this review we will talk again aboutChinese instrument - laser rangefinder (roulette). This is the second model from the company Lomvum, which fell into my hands and it is also 40 meters. But unlike the cheaper and simpler LV40, the LV 66U is slightly higher and has a number of features. These include: a screen with inverted colors enlarged to two inches, the presence of a digital protractor, which can also act as a digital level and be used for calculations on vertical planes, the ability to calibrate and much more.

Specifications
- Model: LV 66U
- Measuring range: up to 40m
- Accuracy: ± 1 mm
- Unit selection: M / ft / in / ft + in
- Laser class: class II, <1 mW, 630-670nm
- Dust and spray protection: IP 54
- Memory: 20 cells
- Auto shut off: 3m
- Working temperature: 0 ~ 40C
- Power supply: 1.5V AAA x2 / 1.2V ni-mh AAA x2
- Dimensions: 115x50x29.5 mm
- Weight: 135 g
The manufacturer has almost twoSame-looking models are LV 66U and LV 77U. The first is simpler, and we will talk about it today. The second is characterized by the fact that it has an input for recharging batteries (ni-mh) and voice alerts. True language of these alerts only Chinese, so for us it will not be a plus, but on the contrary annoying minus.
Packaging and appearance
This time the device came in a branded box,It is in the brand, manufactured specifically for the model LV 66U. This can be understood immediately by looking at the front side, on which the model number stands. Everything is quite familiar in the set:
- the device itself,
- cover with fastening under the belt,
- reflecting plate,
- lanyard
- detailed instructions.

The user manual is very detailed with color illustrations. Languages ​​available are two, Chinese and English. And in the latter information is painted for some reason even more.

Already familiar to us reflecting plate with exactlysame physical dimensions: 90 x 50 x 1 mm. For all the time using range finders, I have never used it, although in theory it should really help us in some situations. For example, if we need to measure the distance to the mirror surface, or to the transparent (glass). Its size seems to me too small to be useful to some extent.

Soft rag case this time a little more thanThe one that was attached with the LV40 model. The device in it dangles and is not fixed tightly, which is not good. But thanks at least for this. The back cover has a special eyelet for attaching to the belt.

Now let's look at the device itself. Made externally in almost the same form as most of the same models from competitors. There are essentially no differences in the design. Before us is a small rectangle with the following dimensions, length - 115.6 mm in width - 50.4 mm and in thickness - 28.4 mm. In comparison with the SNDWAY SW-T80, Lomvum LV40 and Atorch H40 rangefinders, which I previously had on the review, this one has average dimensions. The body is made of matte plastic, mostly black in color with thin inserts on the front side of orange. Holding the device in hand, it creates the feeling that the body is rubberized, but this is actually not the case. It has standard protection against splashes, sand and dust, but you should not drop or submerge it in water, the case is not sealed and does not have protection against water penetration. On the front side there is a display with inverted colors enlarged up to 2 inches, below it is a block of six control buttons.

This is the first model in which the screen has a protective film, albeit a shipping one. Buttons by the way rubberized and pressed not tight, but rather very soft and easy.

On the back we see a sticker with detailed technical features of the device. Unfortunately, there are no tripod mounts again.

The laser power is declared as <1mW, and the wavelength is from 630 to 670nm.

The range finder is powered by two AAA 1.5V batteries (mini-size), or two batteries of the same size Ni-Mh 1.2V.

On one of the sides there is a hole for lanyard, which just comes in the kit.


Lens optics and the laser itself in its usual place- the upper end of the case. The inscription warns us not to look at the laser beam. The bottom "sole" is flat and allows you to put the device on a horizontal surface. By the way, the corners on all four sides have a bevel at an angle of 45 degrees.

Disassembly
The range finder is easily disassembled, just unscrew the four small screws in the corners. Additionally, both parts hold each other with powerful snaps.


As we see, it is built on a 32-bit STM32F microcontroller manufactured by STMicroelectronics.

Control

Using a range finder is easy and simple, especiallyif we talk about the basic functions. The control circuit here is practically no different from a lot of similar devices. If you do not take into account the small additional features that are found in different models, it can be called typical. We analyze it in more detail.
Buttons and functions:
- Turn on-off / Remove - long press to turn the device on or off, short press to clear the latest data,
- MEARS - short press - to perform a single measurement, and long - switch to the continuous measurement mode,
- ± Addition, Subtration - addition, subtraction button / - short press acts as an addition button, long - subtraction,
- Function - measurement of area / volume / according to the Pythagorean theorem, etc.,
- Benchmark / Front Back - short press switches the measurement modes based on the length of the case or without,
- Unit - measurement of units,
- Mute - turn on or on the contrary turn off the sound signal,
- History Record - saving results in a memory cell, navigating through memory cells.
The list of features includes the following:
• measuring the distance to the object, calculating the area and volume,
• support for measurements in meters, inches and feet,
• single or continuous measurement
• indirect measurement function by the Pythagorean theorem
• tracking the maximum and minimum distances on the screen
• simple calculator function (+, -, addition or subtraction)
• measurement with or without body length,
• memory for 20 cells,
• laser pointer for easy pointing,
• large LCD display with backlight on 5 text lines,
• sound indicator
• battery charge indicator
• intelligent computing,
• digital protractor.
• digital level.
Calibration Mode
Detail paint each function I likeusually, I will not, you think you yourself know that this is not necessary. Having twisted the device in the hands of a couple of minutes, everything will become clear. And I’ll tell you better about what is not written on the product page or anywhere else in the instructions. It's about the hidden menu, entering which you can make adjustments to the measurements, i.e. in other words, instrument calibration. As is usually the case, the seller himself really does not know anything about it, so I had to look for the method of "scientific" tyk myself. In the model 66U, which we are talking about today, the entrance to the menu is carried out by simultaneously holding down three buttons. Without releasing them next we press the power button, what we need appears on the screen. As we see from the photo below, in my copy, the factory calibration is intact, i.e. the screen is just four zeros. If necessary, this value can be changed in the range from +10 mm to -10 mm.

In the photo, I also noted which buttons to hold. And let me remind you that the procedure for entering the menu must be performed in the off state!
Practice tests
One of the distinguishing features of this modelthis is her display. The three past rangefinders that I had on the review had, firstly, a smaller diagonal screen (1.44 inches vs. 2 inches at 66U) and secondly, here it is not quite familiar to us, with inverted colors. It was very interesting to find out what his readability is, whether it is worse or maybe the other way around is better. After short tests, it turned out that indoors and at night, the information on it is perceived better, primarily due to the larger and bold text. But in the afternoon, especially under the bright sun, the screen flashes strongly and becomes less readable. In this regard, the usual monochrome screen with white backlight will be preferable. The screen turns off after three minutes of inactivity, and the backlight itself will remain on all this time (in normal screens it usually turns off after 20-30s).

The first practice started the tests, as well asalways, from the verification of measurements at small distances, for this purpose I used a usual tape measure as a standard. The minimum distance that this model can measure is 4.5 cm. But the error is large. Correct measurements start at 5 cm. Therefore, test measurements began with them. The photo below compares at distances: 5 cm, 10 cm and 30 cm. The error is within acceptable limits.

Then the test comparisons were made already at a distance of 3 m and 5 m. The error remained within the limits stated in the characteristics + -1 mm. I did not calibrate the device, I decided to leave everything as it is for now.

In the daytime, the device showed itself only withgood side, I honestly expected the worst. None of the three previous rangefinders could not measure during the day from my window to the next house, but the hero of the review could. The main condition for successful measurement is that the end point, i.e. the surface was not illuminated by direct sunlight. Otherwise there is a big chance to see an error on the screen.

I was also surprised that during the daytime (atcloudy weather) was able to measure such large distances as 62 meters and more. A maximum of hands, which turned out - 83 meters. This is of course an excellent result, though it’s very difficult to see with your eyes. The device is designed only for 40 meters, and during the day I managed to measure twice as much. The receiver power here is likely much higher than that of the LV40.

At night, the result was able to increase to 106 meters. The laser point in this case is already visible at this distance.

In addition to simply measuring the distance, the device stillcan independently calculate the area (it is necessary to measure the length and width of the object), the volume (height is added to the length and width), perform indirect calculations using the Pythagorean theorem (II, III), as well as automatic calculations using the protractor. The last of these functions will be very useful in cases where it is not possible, for example, to make a direct measurement of the height of an object.
An example of calculating the area (m2) of a room and its volume (m3):

An example of indirect calculations of height (h) by the Pythagorean Theorem (by two and three points):


Calculations on vertical planes using the protractor.
Differences from the two sounded above, in that with one / two measurements we immediately get on the screen several indirect measurement results.


The integrated tilt sensor can also be used as a digital level.

Conclusion
Good, good laser tape measure from Lomvum,which in fact all the same was able to surprise. It is easy to use, you can figure out the functionality without even looking at the instructions. The screen increased to two inches in the room has good readability, due to large and fat numbers, but not in the afternoon in bright light. In this regard, used in our rangefinder model, the inverted screen will play a normal LCD (which is installed for example in lomvum lv40).
The package is standard, there is a soft case,lanyard and reflective plate. The accuracy of the measurements, in the course of the tests performed, turned out to be with an error within the acceptable range. But if necessary, it is possible to produce its finer calibration, the benefit is the possibility.
In addition to the main function - distance measurement,also allows you to calculate the area of ​​the room, its volume, indirect measurements by the Pythagorean theorem, as well as calculations using the protractor. The presence of a tilt sensor adds a rangefinder a number of additional features, one of which is to work as a digital level.
The power of the optics was sufficient towork and make measurements even during the day in bright light. The only condition that needs to be met is to try not to direct the beam towards the objects overexposed by the sun. Otherwise we will get an error. Instead of the stated 40 meters, in the daytime the device can easily measure both 60 and even 80 meters. At night, the figure was 106 meters. I have not seen such results before, and I have already managed to test three more different models before. It is difficult to work at long distances, since there is again no mounting for a tripod on the case.