Comparison Crown CT44033 vs Kraissmann 5 LL 30

General type of device.

Modern levels differ primarily in their operating principle: they are optical(traditional or digital) and laser(conventional and rotary). At the same time, the specific specialization depends on the principle of operation - laser and optical devices differ in purpose and application. In turn, the main function of rangefinders is clear from the name - determining distances. The difference here also lies in the principle of operation: most modern rangefinders are laser, but there are also more specific ultrasonic devices.

Here is a more detailed description of each of these varieties:

— Optical level. Levels have a traditional design - in the form of a kind of specialized telescope mounted on a tripod and supplemented with measuring scales (including in optics, in the operator’s field of view), as well as devices for horizontal alignment (compensators, levels). Such devices are used to determine height differences using the so-called geometric leveling method, for which leveling rods are also used - special strips with measuring scales installed vertically. And the general principle of this method is as follows: the operator points the level’s telescope, set horizontally, at the vertical leveling staf...f, and determines which mark on the staff is opposite the main “sighting mark” of the level - this mark will correspond to the actual height of the device. More information about this method, including specific measurement techniques, can be found in special sources. Here we note that optical levels are excellent primarily for working in large areas of open areas; they are used mainly in such fields as geodesy and cartography. But for work where you have to deal with relatively short distances (primarily construction in small areas), such devices are not suitable; However, they are quite complex and expensive, especially compared to laser devices. So, relatively few optical levels are produced nowadays.

— Digital level. In fact, it is an advanced version of the optical levels described above. Externally, they differ primarily in that instead of a regular telescope, such devices are equipped with a digital camera that displays the image on the screen on the control panel. Such levels are used in the same way as “regular” optical ones, but the operating procedure itself is automated and supplemented with a number of advanced functions. Thus, in most models, the operator does not need to manually count the slats, record the results and carry out calculations - the device itself recognizes the recorded marks, stores them in memory and processes the received data, displaying the final result. It is often possible to save information to a memory card or other media, copy it to a PC, or even connect the level to a laptop and use special software (for example, mapping) directly during measurements. On the other hand, such opportunities are not cheap: digital levels are several times, or even orders of magnitude, more expensive than traditional optical ones. So, in general, devices from this category are high-quality devices, designed primarily for professional use - when you often have to deal with large volumes of work, in light of which speed and ease of data processing are of key importance.

— Laser level. A kind of laser projectors that display marks on walls and other surfaces - usually in the form of lines, but there are also models with a dot function (for more details, see “Point projections”) or even only dot ones (see “Purpose”). A classic laser device actually combines the functions of a level and a building level: it can be used both for the above-described geometric leveling using slats, and for constructing planes and marking lines (some models are equipped with mechanisms that allow you to arbitrarily select the angle of inclination). Such devices are well suited for working at short distances, including indoors; and thanks to their relatively simple and inexpensive design, they are very popular, especially in construction. At the same time, we note that some models can have a fairly significant measurement range - up to 50 m on their own and up to 150 m or more using special receivers.
We emphasize that this paragraph includes traditional laser levels, in which the mark line is formed by scattering the beam with a special prism. Rotary models that operate by rotating the emitter are included in a separate section and are described below.

— Rotary level. A variation of the laser levels described above, in which the plane is “drawn” not due to the scattering of the laser beam in the prism, but due to the rapid rotation of the emitter. As a result, the trace from the beam merges into one continuous line for the eye. Rotary levels are usually not cheap and most of them are professional devices designed to work on large areas. The measurement range without a receiver is usually several tens of meters, and with a receiver - up to several hundred. In light of this, when using such devices, you need to be especially careful about observing safety rules - getting a powerful laser beam into your eyes can cause harm to your health, and even the reflection of a laser “bunny” from some surfaces often causes discomfort. So, it is highly advisable to use safety glasses or masks in the operating area of the rotary device.

- Laser rangefinder. Devices for measuring distances using a laser beam. The key advantage of such devices over rulers, tape measures, etc. is that you do not need to move during the measurement process - just place the device at the starting point and point the beam at the object, the distance to which you want to determine. At the same time, the range of action in many models reaches 100 m or more, and the error does not exceed a few millimeters, or even fractions of a millimeter. In addition, modern laser rangefinders can be equipped with various additional functions such as automatic calculation of area and volume, summation of distances, fixation of minimum and maximum, etc. The disadvantages of such devices include reduced efficiency in the presence of fog, heavy dust or other similar contaminants air, as well as difficulties in measuring distances to glass and other transparent objects that transmit the laser beam rather than reflect it. However, these moments are not so often critical, and in terms of performance characteristics, laser devices are noticeably superior to ultrasonic ones. Therefore, this type of rangefinder is the most popular in our time.

— Ultrasonic rangefinder. Range finders using ultrasound; In such devices, a laser is also often installed, but it is intended solely for precise pointing at the desired object and is not used for measurements. In any case, rangefinders of this type are good because their effectiveness practically does not depend on the purity of the air and the type of surface on the object being measured: ultrasound works perfectly through dust, smoke, fog, etc., and is also reflected perfectly from glass and other transparent materials. laser materials. On the other hand, in terms of “range” and accuracy, such devices are noticeably inferior to laser ones: the measurement range in them does not exceed 15 - 20 m, and the error is calculated not in millimeters, but in percentages - usually about 0.5 - 1% (which, for example, at a distance of 10 m corresponds to an actual error of 5 - 10 cm). As a result, rangefinders of this type are much less common than laser ones these days.

The range at which the device remains fully operational without the use of additional receivers (see below); in other words, the radius of its action without auxiliary devices.

In some models, a range may be specified that shows the minimum ( 3 cm, 5 cm) and maximum measurement ranges. But in most cases, only the maximum value is indicated.

The specific meaning of this parameter is determined by the type of instrument (see above). So, for optical levels, the measurement range is the greatest distance at which the operator can normally see the divisions of a standard leveling staff. For laser levels, this parameter determines the distance from the device to the surface on which the mark is projected, at which this projection will be easily visible to the naked eye; and in rangefinders we are talking about the greatest distance that can be measured. Typically, the measurement range is indicated for ideal conditions - in particular, in the absence of impurities in the air; in practice, it may be less due to dust, fog, or vice versa, bright sunlight "overlapping" the mark. At the same time, tools of the same type can be compared according to this characteristic.

Note that it is worth choosing a device according to the range of action, taking into account the features of the tasks that are planned to be solved with its help: after all, a large measurement range usually sig...nificantly affects the dimensions, weight, power consumption and price, but it is far from always required. For example, it hardly makes sense to look for a powerful laser level at 30-40 m if you need a device for finishing work in standard apartments.

Accuracy is described as the maximum deviation from the true value of the measured parameter, which the device can give if all the rules for its operation and the corresponding measurements are observed. In both rangefinders and levels, this parameter is usually designated for a certain distance — for example, 3 mm at 30 m; but even for one manufacturer, these "control" distances may be different. Therefore, in our catalog, the accuracy of all devices is recalculated for 1 m distance; with such a record, for the example above, it will be 3/30 \u003d 0.1 mm / m. This makes it easier to compare different models with each other.

It is also worth mentioning that the meaning of the "accuracy" parameter for different types of measuring instruments (see "Type") will be different. For optical levels, it is described in the "SKP" paragraph above. For laser levels of all types, accuracy is the maximum deviation of the mark from the true horizontal (or vertical, if such a function is provided), and for the horizontal, we can talk about both moving the mark up / down and turning it. In rangefinders, this characteristic describes the maximum difference (both in "plus" and "minus") between the readings of the device and the actual distance to the object.

Anyway, the smaller the error, the better; on the other hand, accuracy significantly affects the price of the device. Therefore, it is necessary to choose a specific model for this parameter, taking into account the...specifics of the planned work. For example, for a relatively simple repair in a residential apartment, a high-precision tool is unlikely to be required; and recommendations for more complex tasks can be found in specialized sources, ranging from expert advice to official instructions.

Measuring accuracy provided by a laser distance meter (see "Type")

This parameter is traditionally indicated by the error - the maximum deviation of the obtained results from the actual values, which may occur due to the imperfection of the device. The physical features of laser rangefinders are such that in such devices the error is practically independent of the measured distance. Therefore, the accuracy of such rangefinders is indicated in millimeters. At the same time, in our time, models are generally considered to be high- precision, where this indicator does not exceed 1.5 mm (in some models it is only 1 mm); but even in relatively simple and inexpensive devices, deviations of more than 3 mm are practically not encountered.

The general selection rules for this indicator are traditional: the more accurate the device, the more expensive it is, as a rule. In addition, we emphasize that for everyday and even many professional tasks, the difference described above is not fundamental in accuracy. Therefore, it makes sense to specifically look for a rangefinder with a minimum error in the case when the measurement accuracy “to the millimeter” is fundamental. At the same time, it should be borne in mind that for such measurements, appropriate accuracy in the placement and use of the device itself will be required - otherwise, all the advantages will be nullified by errors from incorrect installation and operation.

The maximum deviation from the horizontal position that the device is able to correct "by its own means".

Self-leveling in itself greatly simplifies the installation and initial calibration of levels (see "Type"), which often (and for optical models — mandatory) need to be set horizontally to work. With this function, it is enough to install the device more or less evenly (in many models, special devices are provided for this, such as round levels) — and fine tuning in the longitudinal and transverse planes will be carried out automatically. And the limits of self-leveling are usually indicated for both planes; the higher this indicator, the easier the device is to install, the less demanding it is to the initial placement. In some models, this figure can reach 6 – 8 °.

The number of reference points provided in the rangefinder (see “Type”).

The reference point is called “conditional zero” - the point from which the device begins to measure distance. If the device states only one reference point, then this is, as a rule, the rear edge of the case. However, there are few such models on the market, mostly the simplest and most inexpensive rangefinders. Devices with two such points are much more popular - usually the rear and front edges of the case. There are also more advanced options - three or even four reference points. In the first case, the role of an additional conventional zero is played by either a folding stop bracket or a mounting point on a tripod; and the second usually provides both a bracket and a tripod socket.

In any case, a larger number of reference points provides more measurement possibilities, but increases the cost of the device.

The temperature range at which the device is guaranteed to work for a sufficiently long time without failures, breakdowns and exceeding the measurement error specified in the characteristics. Note that we are talking primarily about the temperature of the device case, and it depends not only on the ambient temperature — for example, a tool left in the sun can overheat even in fairly cool weather.

In general, you should pay attention to this parameter when you are looking for a model for working outdoors, in unheated rooms and other places with conditions that are significantly different from indoor ones; in the first case, it makes sense to also make sure that there is dust and water protection (see "Protection class"). On the other hand, even relatively simple and "myopic" levels / rangefinders usually tolerate both heat and cold quite well.

The standard size of the thread used to mount the level/rangefinder on a tripod (if available). This option can be useful if you already have a surveying tripod that you want to use with the tool.

The most popular options in modern devices are 1/4" and 5/8". It is worth noting that 1/4" is a standard size for photographic equipment - accordingly, levels with such a thread can be installed even on ordinary photographic tripods.

The wavelength of the radiation emitted by the LED of the level or rangefinder; this parameter determines primarily the colour of the laser beam. The most widespread in modern models are LEDs with a wavelength of about 635 nm — at a relatively low cost, they provide bright red radiation, giving a well-visible projection. There are also green lasers, usually at 532 nm — the marks from them are even better visible, but such LEDs are quite expensive and rarely used. And radiation with a wave longer than 780 nm belongs to the infrared spectrum. Such a laser is invisible to the naked eye and is poorly suited for leveling, but it can be used in rangefinders — of course, with a viewfinder (see "Type" for more details).