Accuracy
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.
Operating temperature
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.
Tripod thread
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.
Auto power off
The ability
to automatically turn off the device after a certain time. This function is found in those types of measuring instruments that require power for operation — first of all, we are talking about laser rangefinders, however, this list may also include levels (see "Type"), both laser and optical with additional digital modules . The main purpose of auto-shutdown is to save electricity: after all, almost all such devices have autonomous power sources (see "Power"), the charge of which is not infinite. Forgetting to turn off the device, you may encounter an unpleasant situation: the batteries are dead, but there are no fresh ones at hand; auto-off prevents these situations and generally increases the operating time without changing batteries or recharging the battery. In addition, this feature is also useful from a safety point of view: automatic laser shutdown reduces the likelihood that its beam will accidentally fall into the eyes of someone around (including a forgetful operator).
In some models, auto-shutdown works on the entire electronics, in others it may be possible to turn off the laser first (as the most energy-intensive and unsafe part), and only after a while — all other electronic circuits.
Auto power off
The time after which the device turns off by itself completely if the user does not perform any action.
See above for more information on auto power off; and his time has a double meaning. On the one hand, if this time is short, then the idle time of the device will be minimal, which helps to save energy. On the other hand, too frequent auto-shutdown (with subsequent switching on for work) is also undesirable — it increases the wear of components and reduces the resource, and it is not always convenient for the user. So manufacturers choose the time, taking into account the balance between these moments, as well as the general class and purpose of the device. So, in some rangefinders, this indicator does not even reach a minute, although in most such devices it is in the range from 3 to 8 minutes; and in some professional devices (primarily levels), the auto-off time can be 30 minutes or more (up to 3 hours).
Diode emission
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).
IP protection rating
The level of protection against harmful influences (in the first place — the penetration of foreign objects) that the body of the level / rangefinder provides in accordance with the IP standard. This standard describes two separate characteristics — protection against solid objects and against water. They are designated respectively by the first and second digit after the IP index; the higher the number, the higher the degree of protection.
Considering that levels and rangefinders usually have to work on construction sites where there is a lot of dust, the minimum level of protection against solid objects for such tools is the fifth. It allows some dust to get inside, but in such a way that it does not affect the performance of the device. The maximum level of dust resistance is 6, which implies complete protection from solid particles.
The second characteristic, protection against moisture, in levels and rangefinders is usually indicated starting from level 4. Officially, it provides protection "against spray from any direction", in fact this means that it can be used in moderate rain with strong winds — a useful point in that if the tool is to be used outdoors. Level 5 allows operation during storms and downpours, a device of the sixth class can withstand being hit by a wave, the seventh — a short-term immersion under water up to 1 m, and the eighth — even a long stay under water. However, for a conventional construction tool, too high water resistance i...s usually not required.
Actually, the most popular option in modern construction tools is the IP54 class: it is quite enough even for work in bad weather, while such cases are relatively inexpensive. There are also more protected models, but less often.
It is also worth noting that a certain level of dust and water protection in itself is usually provided even in devices that do not have an IP marking. The absence of this index does not necessarily mean the absence of protection — it only says that the case has not been officially certified according to the IP standard. But if you need an additional guarantee of reliability, you should still pay attention to certified options.
Power source
The type and number of batteries used in the level/distance meter. All elements of standard sizes (
AA,
AAA,
C,
D,
PP3) are available in two formats — disposable batteries and rechargeable batteries. This gives the user a choice: either buy relatively inexpensive batteries every time, or invest once in a rechargeable battery with a charger, and then simply charge the battery as needed.
Branded batteries are, by definition, made only rechargeable, as are
18650 batteries.
Specific types of power today can be as follows:
— AA. A standard battery, known as a "finger battery". The power of these batteries is average, they can be used both in simple and quite advanced devices. This power supply is convenient due to the fact that AA batteries are very widespread and sold almost everywhere — due to this, finding and replacing them is usually not a problem.
— AAA. A smaller version of the AA element described above — almost identical in shape, but thinner and shorter. Such elements, known as "mini-finger" or "little fingers", have a rather low capacity and power, but are useful for portable devices, where compactness is crucial. They are also quite widespread.
— C. A cylindrical element, in the form of a rather thick "bar
...rel" — with a length of 50 mm, the diameter is 26 mm. Due to its higher capacity and power than AA, it is better suited for advanced models with "long-range" lasers, but is less commonly used and generally less common.
— D. The largest and most capacious type of standard batteries found in modern levels and distance meter: thickness and diameter are 62 and 34 mm, respectively. The main area of application for D batteries is powerful professional devices.
— Rechargeable battery. In this case, the tool is powered by an branded battery that does not belong to any standard size. This option is good because such batteries are initially created for a specific model of the level/distance meter and are supplied in the set (and in some models they are made non-removable); in addition, their specifications can significantly exceed those of standard elements of a similar size and weight. On the other hand, such power source is less convenient when the charge runs out at the wrong moment: the only way to remedy the situation is usually to recharge, and it takes quite a long time (whereas standard batteries can be replaced in just a minute).
– 18650. The name of these batteries comes from their dimensions: 18.6x65.2 mm, cylindrical, outwardly they resemble somewhat enlarged AA batteries, but they have an operating voltage of about 3.7 V and a higher capacity. In addition, all 18650 type batteries are by definition not disposable, but rechargeable batteries (lithium-ion type).
— PP3. 9-volt batteries of a spesific rectangular shape, with a pair of contacts on one of the ends. Due to the high operating voltage, they provide high power and actual capacity, so one such battery is usually enough for operation.
— LR44. Miniature batteries of "coin" type, 11.6 mm in diameter and 5.4 mm thick. Usually installed in sets of 3 and are used in compact low-power laser levels, for which small size is more important than power and capacity. Note that specifically the LR44 marking refers to relatively inexpensive alkaline batteries; more expensive and advanced silver-zinc power supplies are referred to as SR44, or 357.
— 23A12V. A rather rare option: cylindrical batteries (length 29 mm, diameter 10 mm) with a nominal voltage of 12 V.Operating time
Operating time of the device on one battery charge.
It is worth considering that these figures are quite approximate, since the operating time is measured under certain standard conditions (usually continuous operation at nominal power). And since in practice conditions may differ markedly, the operating time may turn out to be noticeably shorter or longer than stated. In addition, if the device uses replaceable batteries (AAA, AA and the like), then autonomy will also depend on the quality of the specific batteries/accumulators. Nevertheless, based on the data specified in the characteristics, it is quite possible to evaluate the capabilities of specific models and compare them with each other: the difference in the declared operating time, as a rule, proportionally corresponds to the difference in practical autonomy under the same conditions.
We also note that the operating time is specified mainly for levels; in rangefinders another parameter is more often used - the number of measurements (see below).