Sights on a firearm can also act like a rangefinder by aligning the vision of the shooter through sighting aids. Modern day rangefinders use active means like radar, laser, ultrasonic and other methods to make more accurate assessments of distances. Rangefinders are used by people during surveying or while hunting or playing golf.
Optical rangefinders use lenses for measuring distances with the help of scales that are built into the instrument. These devices do not need any batteries or other power banks, like those that use lasers, radar or sonar impulses for determining distances. They are more dependable, though accuracy may depend on the user. They are also cheaper than the more modern instruments. These rangefinders are used by golfers to judge the correct distance to the next green or portion of the fairway so that they can use the necessary force during their swing or drive. The use of this variety of rangefinders does require practice and skill if the right results are to be obtained. They can also be of use in hunting and are less likely to mistake trees and other objects than the actual game being hunted.
Rangefinders will have reticles or cross hairs that are used to aim the device towards the point whose range is to be estimated. These can also be in the form of circles that are meant to focus on the distant object. Some rangefinders, especially those used by surveyors will give a direct reading of the distance so that it can be easily noted or sent on to recording devices. Architects and designers find them very useful for measuring rooms and heights without the need to hold tapes.
The knowledge of the correct distance can help in deciding the type of club to be used during a golf game and this information is easily availed of by using a rangefinder to sight the next flag or object. Rangefinders used for hunting, golf and in the open must be easy to carry and light in weight. They also need to be able to resist rough weather and be proof from rain. Many models have built-in compasses and thermometers that can help outdoor enthusiasts.
Typical rangefinders are used for distances between 500 and 1200 yards. Longer distances can be subject to problems with visual sighting due to parallax, dust , haze and other obstructions. Rangefinders are available in most sports goods stores and a number of models can also be seen on the internet. They do require getting used to and some practice before they can prove their usefulness. It can always help to hire one or borrow one before you decide on buying your own.
Rangefinders have found substantial use in military and policing operations and have helped to make things much easier. Their use by engineers and architects has also been widespread.