Comparison Bosch GCL 25 Professional 0601066B00 vs Bosch GOL 20 D Professional 0601068400

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 one has to deal with relatively short distances (primarily construction in small areas), such devices are poorly suited; 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 there is no 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.

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 °.

Approximate time it takes for the self-levelling mechanism to bring the level to a perfectly level position.

For more information on such a mechanism, see Self-Level Limits. And the actual time of its alignment directly depends on the actual deviation of the device from the horizontal. Therefore, in the characteristics, usually, the maximum alignment time is given — that is, for the situation when in the initial position the device is tilted to the maximum angle along both axes, longitudinal and transverse. Since the levels are far from being installed in this position, in fact the speed of bringing to the horizontal is often higher than the claimed one. Nevertheless, it makes sense to evaluate different models precisely according to the figures stated in the characteristics — they allow you to estimate the maximum amount of time that will have to be spent on alignment after the next movement of the device. As for specific indicators, they can vary from 1.5 – 2 s to 30 s.

Theoretically, the shorter the alignment time, the better, especially if there are large volumes of work ahead with frequent movements from place to place. However, in fact, when comparing different models, it is worth considering other points. First, we reiterate that the rate of leveling is highly dependent on the leveling limits; after all, the greater the deviation angles, the more time it usually takes for the mechanism to return the level to the horizontal. So, to directly compare w...ith each other in terms of the speed of self-leveling, it is mainly those devices in which the permissible deviation angles are the same or differ slightly. Secondly, when choosing, it is worth considering the specifics of the proposed work. So, if the device is to be used frequently on very uneven surfaces, then, for example, a model with a leveling time of 20 s and self-levelling limits of 6 ° will be a more reasonable choice than a device with a time of 5 s and limits of 2 °, since in In the second case, a lot of time will be spent on the initial (manual) installation of the device. And for more or less even horizontal planes, on the contrary, a faster device may be the best option.

The degree of magnification provided by the lens of an optical level or laser rangefinder (if this function is available, see "Type" for details). Anyway, the greater the degree of magnification, the greater, usually, the range of the device (see above) and the more convenient it is to work with it at a distance. For optical levels, this parameter is also one of the criteria that determine the suitability of the instrument for a particular measurement class; specific requirements for multiplicity, usually, are indicated in specialized instructions.

Note that an increase in magnification, other things being equal, leads to a narrowing of the field of view; To some extent, this can be compensated by increasing the diameter of the lens (also see below), but large lenses significantly increase the overall cost of the level. Therefore, when choosing, it is worth proceeding from the optimal balance between these characteristics.

The diameter of the lens of the optical level (see "Type"). First of all, the aperture ratio, the amount of light transmitted by the optical system, depends on this parameter. The larger the lens diameter, the higher this number and the brighter and clearer the image visible to the operator is, which is especially important in low light conditions (in cloudy weather, at dusk, etc.). In addition, a large lens allows you to increase the angle of the field of view; for more on this, see p. "Magnification".

The root mean square measurement error that occurs during the operation of an optical or digital level.

This indicator is noticeably lower than the deviation indicated in the “Accuracy” paragraph: if the accuracy is indicated in millimeters per meter, then the SKP is in millimeters per kilometer (more precisely, the so-called “double-track kilometer” - a route 500 m long, traveled there and back). There are no contradictions here: the SKP describes exclusively the error caused by the imperfect design of the device itself and arises under absolutely ideal measurement conditions, while the accuracy characterizes the “level-staff” system and describes deviations that are relevant for real conditions. Therefore, SKP as a whole is a formal parameter used to divide levels into accuracy groups - high-precision, precision and technical. The first category includes devices with SCP up to 1 mm/km, the second - up to 3 mm/km, and the third - all less accurate. The minimum accuracy groups required for certain types of work are described in special sources - in particular, regulatory documents and instructions.

The smallest focal length of an optical or digital level (see "Type").

The focal length in this case means the smallest distance to a leveling staff or other object at which the device can clearly focus on it. In most modern levels, this distance does not exceed 1.5 m, and in some models it is about 20 cm at all. So, from a practical point of view, this is more of a reference than a really significant parameter — after all, such devices are used at much greater distances. At the same time, with similar basic characteristics, a shorter focal length, usually, means more advanced and high-quality optics.