Ultrasonic Versus Laser Tape Measuring Devices
Digital Sonic and Laser Distance Measuring Tools and Equipment
Nov 3, 2009
Laser and ultrasonic digital distance measures can be significantly faster or more accurate than the classic contractor's steel roll-up auto-retracting measuring tape. No more fighting with a floppy ribbon of steel. They allow measurements to be made:
- Without needing a second person to hold the other end of the tape.
- Over furniture and other obstructions.
- Without needing a ladder to reach the ceiling.
- Across waterways or busy roads.
While they might not be worth the cost to a DIY homeowner they can save a busy realtor, painter, insurance adjuster or carpenter hours of fumbling around every week. Not to mention having to frequently replace creased and scratched steel tapes.
New models are small and light, and look like a cell phone or TV remote control. They do have their quirks and limitations. Some tricks are needed to get the best out of them.
Laser Versus Ultrasonic Measures
Ultrasonic measures are often confused with laser measures, partly because some ultrasonic measures have a laser pointer to help in aiming. Manufacturers sometimes label their ultrasonic measures "laser" even if they don't have a laser pointer. Real laser measures:
- Cost more than $100. Ultrasonic measures typically cost between $25 and $50.
- Have accuracies of 1/4 to 1/16 inches. Ultrasonic measures have accuracies of between 1 to 4 inches.
- Have ranges of 150 to 600 feet (50 to 200 meters). Ultrasonic measures normally can't measure more than 50 feet.
Ultrasonic Distance Measures
As can be seen from the comparison above, ultrasonic measures are basically cheaper and less capable than laser measures. They can be accurate enough for estimating the required amount of paint, carpet or tile to cover a wall or floor, but can't replace a measuring tape for precision carpentry.
One major limitation is that they work best with large, flat and smooth surfaces: blank walls and ceilings in empty rooms. Textured walls and obstructions (furniture, ceiling fans and lights) can cause echoes that will interfere with the readings. The problem is that it is difficult to tightly focus the ultrasonic beam. Small objects such as beams or pillars cannot be targeted.
This means that depending on the model and the condition of the room, the accuracy can be much worse than the official 1 to 4 inches. Professionals who depend on reliable measurements should seriously consider paying more for a laser measure.
Digital Laser Range Finders or Distance Measures
Laser measures cost from $100 to a few hundred dollars (industrial models can cost thousands). Warranties range from 1 to 3 years. Popular brands include Leica (Disto), Craftsman (AccuTrac), Stanley (FatMax) and Black & Decker.
High-end models are accurate to 1/16 inches (1.5mm): good enough for carpentry. Older models could not measure distances less than a few feet but new models have minimum distances of a few inches.
Advantages:
- High accuracy.
- Good range.
- Precise aiming. The laser's dot can be used to select individual beams, pillars.
Disadvantages and limitations:
- Can be difficult to see the laser in bright sunlight, reducing the maximum range. Wearing laser-enhancing glasses can help.
- Can be difficult to see the laser on dark surfaces.
- Reflective targets might be needed to achieve maximum range.
- Can be confused by shiny, reflective surfaces.
- Needs a surface to reflect off. If no surface is available (measuring the length of external walls, distance between electrical sockets) a piece of cardboard or other material can be used as a target.
- Needs to be held steady to get a reading. For long range measurements, a tripod or other support is required.
- Needs clear line of sight. This can be a problem in gardens.
Useful features:
- Clear confirmation that measurement was successfully completed (beep, LED flash), no need to look at LCD display.
- Backlit LCD display.
- Standard 1/4 inch camera tripod socket.
- Ability to measure from the back, front, or tripod socket.
- Tilt measure or spirit level to ensure that horizontal measurements are accurate.
- Automatic power-off to preserve the batteries.
- Optical sights to help aim the laser.
- Readings in feet/inches (10 feet, 4.5 inches), decimal inches (124.5 inches), fractional inches (124 8/16 inches), metric.
- Area and volume calculations.
- Addition and subtraction of lengths.
- Indirect measurement of length using Pythagoras Theorem for right angled triangles.
- Low battery warning.
- Continuous measurement, useful for locating positions a fixed distance from a reference point.
- Saving of user settings after power off (feet/inches or meters, measure from front or back).
- Squared-off sides so that the beam is perfectly horizontal or vertical when the measure is placed on the floor.
Laser Versus Ultrasonic Versus Tape Measures
Laser measures are quick and precise, a good choice for people who measure every day. Considering the time saved, every professional should consider getting one. For longer distances, golf or hunting laser range finders can be used, though accuracy is limited to about a yard.
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