Wndsn Quadrant Telemeters

Wndsn Quadrant Telemeter Tutorials

Making the most out of our graphical telemetry computers.

Like with many complex instruments, there are multiple ways to solve certain problems and to measure the required inputs. Combining the various functions leads to a multitude of advanced uses. See also the printed manual.

Measuring MIL with the Telemeter

Level: Advanced

[This trick works with all Telemeters that are calculated for an eye distance of 57.3 cm (180/π). For other values ​​on the α scale, the knots must be adjusted accordingly.]

With an additional knot on the string at 50 cm (19.69 inches) you can take measurements in MIL. The α (angle) scale thus becomes a MIL scale with a resolution of 2 MIL per scale mark (i.e. 2 MIL at 0.1°, 10 MIL at 0.5°, 20 MIL at 1°, etc.).

The math behind it: a MIL, also known as a milliradian, is the angle at which an object with a size of 1 unit is seen at a distance of 1000 units. This means that an object with a width of one centimeter at a distance of 1000 centimeters has an angular size of one MIL.

The perceived image of this object at a distance of 50 centimeters from the observer then corresponds to:

1 cm / 1000 cm · 50 cm = 50 cm / 1000 cm = 0.05 cm = 0.5 mm

Since the α scale of the Telemeter corresponds to a metric scale with 1 mm distance per 0.1°, one millimeter corresponds to an angle size of 2 MIL. After we have measured the angular size of our object in MIL, we can do the further calculations of the distance or the object size with the MKS formula, as described in our tutorial under MIL vs. MRAD vs. NATO-MIL and use all the advantages of the measurement in MIL.

What if the object is bigger or closer? The answer is to extend the angle scale. How? Using additional knots on the string, as described in Extending the Scales.

In order not to mix up the knots for the measurements in degrees and for the measurements in MIL, it is advisable to mark the new knots with permanent marker or colored string.

In the table below you can find further positions for further knots on the string to expand the scales in MIL, as well as multipliers to calculate the distance more quickly if the size is known. These multipliers can also be used as divisors for calculating the sizes or heights when the distance is known. Of course, the Telemeter nomogram on the MIL calculator can be used with the MIL input. (The Telemeter nomogram in degrees does not work in MIL.)

(Thanks to Telemeter user Andrej for this trick!)