AOFAR AF-4074 Military Compass Instruction Manual

AF-4074 Military Compass

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Product Specifications

1. Model: AF-4074
2. Color: Army green
3. Size: 100x66x31mm
4. Dial Diameter: 50mm
5. Weight: 287g
6. Material: Zinc alloy
7. Clinometer: Yes
8. Waterproof: Yes
9. Luminous: Yes

Product Usage Instructions

1. How to Use the Compass

Move the lid(1) and adjust it up or down until the Aiming
Point(15), aiming line (3), and the object are on a straight line.
Keep the compass horizontal by using the integrated spirit
level(7).

2. Achieving Accuracy

Ensure the Arming line(3) corresponds to the Aiming Point(15) by
keeping the compass at a distance of 1-2cm from your eyes. This
method allows for precise readings to the fraction of an angular
degree.

3. Defining Marching Direction

Aim at an object through the Aiming Point (15) and aiming line
(3). Read the marching direction value on the compass card (13)
which corresponds to the azimuth of the object.

4. Following the Marching Direction

Look at the compass card(13) and turn around until the value of
the marching direction appears on the graduated dial.

5. Map Orientation

To orientate a topographic map, align the geographic north of
the map with the magnetic north of the earth.

6. Defining Position on the Map

Select two visible points on the ground, mark them on the map,
measure the degree of position (A) with your compass, and draw a
line on the map accordingly.

Frequently Asked Questions (FAQ)

Q: How do I adjust the lid for accurate readings?

A: Move the lid up or down until the Aiming Point, aiming line,
and object are on a straight line while keeping the compass
horizontal.

Q: How do I use the luminous feature of the compass?

A: The luminous feature allows for visibility in low light
conditions. Charge it under a light source and it will glow in the
dark.

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1COMPONENTS NAME
13. 360°compass card (Thermoelastic Liquid-Filled Capsule with Floating Dial) 14. Holding Ring 15. Aiming Point

1. Lid 2. Reading Lens or Prism 3. Window with Aiming line 4. Hinge 5. Scale (Centimeter Ruler on
opposite side) 6. Tripod Connection 7. Spirit level 8. Glow-in-the Dark Arrow No1 9. 360° Rotating Bezel Ring 10. Glow-in-the Dark Arrow No2 11. Clinometer 12. Glow-in-the Dark Circle (Fixed tip point)
16. Sighting Lens with Adjustable Diopter 17. Heavy-duty zinc Die-Cast 18. Conversion chart:Angle/Gradient/Distance 19. Distance-measuring notches

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2PRODUCT SPECIFICATION

1. Model

AF-4074

The compass consist of a Zinc alloy housing and a metal lid(1) with

2. Color

Army green

a glass window which the Aiming line etched into it.

3. Size

100x66X31mm The Window(2) is mounted in the lid(1) with a robust hing that can

Dial diameter

5. Weight

6. Material

7. Clinometer

8. Waterproof

9. Luminous

50mm
287g Zinc alloy Yes Yes Yes

be turned through 180°.This allows the Window to be moved into reading position and be folded back after use. The compass is provided with a clinometer enabling you to measure slopes and gradients in degree or in percent. The compass is provided with an integrated spirit level(7). It can be screwed on a tripod (at the back) that means often threaded fitting in the base and serve as theodolite for simple

terrain surveys.

This lens system(16) being provided with an integrated index line and an excellent magnifier allows extremely

precise reading.Problems inevitably caused by mirror reading and potential parallax errors are eliminated by

prismatic reading.

Excellent damping of the dial system ensures rapid and precise reading to the fraction of a degree.

3USE TIPS

Move the the lid(1),adjust the lid either up or down until the Aiming Point(15), aiming line (3) and the object on a

straight line.While doing so keep the compass exactly horizontal by using the integrated spirit level(7).

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By skillfully handing the compass the Arming line(3) corresponds to the Aiming Point(15), thus ensuring that eyes,compass dial and object are at same level and resulting in utmost accuracy.This method allow to read the fraction of an angular degree.
Adjust the position of the prism or lens which on the 360° Rotating Bezel Ring (9 ) until you see distinctly the numbers of the compass card(13 ).In models with adjustable eyepiece,the Sighting Lens(16) must be rotated until numbers in degree are clearly visible.
Optimeal results are obtained when you keep the compass at a distance of 1-2cm from your eyes.
4HOW TO DEFINE THE VALUE OF MARCHING DIRECTION With your compass in reading position,aim at an object,sighting it through the Aiming Point (15 ) and the aiming line(3).Now read the value of your marching direction on the compass card (13 ) which also correspond to the azimuth of the object.
5HOW TO FOLLOW THE VALUE OF THE MARCHING DIRECTION YOU DEFINED If the value of the marching direction is known,look at the compass card(13) and turn around until said value appears on the graduated dial.
6MAP ORIENTATION For more complicated operations to be camied out on the topographic map, it is necessary to orientate the geographic north of the map with that magnetic of the earth .
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Place the compass on the map.Align the centimeter-marked line(5) with that meridian closest to your position,so that the upper lid (1) points to the north of the geographic map. Meridians are parallel lines running from the upper to the lower part of the map . Holding the compass in position ,rotate the map until the north-seeking needle(10) on the dial coincides with the index line of the Glow-in-the Dark Circle(12) . The map is now oriented with the ground. 7LET’S DEFINE THE MARCHING DIRECTION ON THE MAP a) After you aligned you map with the north pole(the description in Point 6,draw a line on the map starting from you position to your final destination. b) Place the compass on the map with one contact edge along the line which is running from your own position to the objective .the compass lid indicates the direction of the objective. c) Read the value of marching direction on the compass card (13) which corresponds to the index line of the Glow-in-the Dark Circle(12) . d) Remove the compass from the map ,look at the compass card (13)and turn around until the value of your marching direction(defined as described point C ) e) Find an auxiliary destination point which must be on the same survey line and start following it . f) Repeat this operation until you reach your final destination.
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The longer your route,the more you have to repeat the above operation which will help you keep the direction you defined. 8LET’S DEFINE OUR POSITION ON THE MAP
Select two well visible points on the ground and mark them on the map .Once the map is orientated (operated as Point 6),with your compass measure the value in degree of position (A) and draw a line on the map in accordance with said value.Now pass through point (B).
9LET’S USE THE CLINOMETER The clinometer is an instrument allowing the measuring of differences in height and slopes.It can be pendular or automatic. Open the compass, adjust the Clinometer (11),until it is perpendicular to the case(17).Aim at the upper(or inferior) edge of your target by the Aiming line(3)(inferior side),Pay attention as to create one single line.The more your tilt the your compass,the more the clinometer changes its position. Aim at the target and tilt the compass on the clinometer side so that the pendulum stops and read the angle of inclination. If the object be located inferiorly to the observer,simply turn the compass until the hinge(4) points to you ,aim at it by viewing through the upper part of the lid and proceed in accordance with the above mentioned instructions.
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Table 2

Angle 0-360
1 2 3 4 5 6 7 8 10 12 14 17 18 20

Angle 0-4600
18 35 53 71 89 107 125 142 178 219 250 302 320 355

Angle 0-400
1 2 3 4 5 6 8 9 11 13 16 19 20 22
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Gradient %
2 3 5 7 9 10 12 15 18 21 25 30 33 36

width/distance
1/60 1/30 1/20 2/30 7/80 1/10 1/8 1/7 1/6 1/5 1/4 3/10 1/3 3/8

22

391

25

40

2/5

24

426

27

45

4/9

27

480

30

50

1/2

31

551

36

60

3/5

34

604

38

66

2/3

35

622

39

70

7/10

37

658

41

75

3/4

40

711

45

84

5/6

42

747

47

90

9/10

45

800

50

100

1/1

50

889

56

120

1+1/5

Angle

Angle

Angle

Gradient width/distance

0-360

0-4600

0-400

%

10HOW TO ESTIMATE THE DISTANCE TO THE OBJECT BY THE MAP

Measure the distance to the object on the map by Centimeter Ruler (5), Multiply the scale of the map.

Map Scan:1:25000

Distance(M) =Distance (mm)on the map X 25000÷1000

Map Scan:1:50000

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Distance(M) =Distance (mm)on the map X 50000÷1000

11THE HEIGHT OF AN OBJECT
You can measure or estimate the distance to the object on the map under Point 10.

Multiply this distance by the factor indicated in column IV or V (Table 2) (whichever is easier for you), referring to the angle in column I measured with the clinometer (the description in Point 9) .

The above mentioned example is based on an angle of 14 and a distance of 2000m.

2000m X 25 column IV (Table 2)
100% OR 2000m X 1/4 column V (Table 2)=500m

=500m

12HOW TO MEASURE THE ANGLE
Measure the right side of the object . Keeping in mind the value in degree that you defined ,slowly orientate the compass towards the left side of the object.From the first value in degree deduct the second value you just defined . The difference represent the value in degree of the angle between the left and right sides of the object.
N.B:Measure of the angle through the north .If the value 360°(north)come across the direct line on the Glow-in-the

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Dark Circle(12) during your measuring operation,consider 360°=0°.The calculation will be 360°-second value in degree +first value in degree. Example: If the first value in degree is 4 and the second is 354,the angle will be 10.360-354+4=10. 13HOW TO MEASURE THE DISTANCE ON THE GROUND In accordance to the principle mentioned under point 10 11 and 12 ,it is possible to define the distance on the ground between two well-visible points on the ground. For example ,you can measure the width of a farm house ,the length of a bridge,etc. There is one necessary condition to measure the distance from your own position to that of the object:the line running from these two positions must be as perpendicular as possible to the side of the object to be measure Example:
At a distance of 4000m, a bridge spans a river, transverse to the line of vision.How long is the bridge if an angle of 6°is measured from the right to the left river bank? 6°=10% or 1 /10 4000×10%=400m OR 4000X1 /10=400m 14MEASURE OF THE DISTANCE OF AN OBJECT,THE HEIGHT AND/OR WIDTH OF WHICHARE KNOWN
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If the height or width of an object is known or drawn from a map,it’s distance will be defined by simply inverting the calculation mentioned above the description in Point 13.

In other words ,if the width of an object with an angle of 8,is 1/7 of the distance according to the table 2 ,the same will be reverse case , the distance is 7 times wider than the width or height.

Example 1:

A TV-tower is visible in the field and its height is known to be 200 m. The angle measured with the clinometer is 7° from bottom to top of the tower.Column IV (gradient in %)indicates 12% for 7°.

100 X 2000m (height of object) 12%(column IV (Table 2))

=1600m

OR 200m x 8(inversion of 1/8) =1600m

Example 2

The angle measured between object B and C (see figure) is 34°. The distance between B and C is 5 km according to
the map column IV ,Table 2 indicates 66%. 100 X 5km =7.5km OR 5km X 3/2 = 7.5km

66%

When using this method,the object of known width must be

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perpendicular to the line of sight.

15MEASURE THE DISTANCE WITH SCALE-MARKED GLASS

1. Aiming line

2. Horizontal line with measuring notches 3. Measuring line

4. First object

5. Second object

The glass cover with the aiming lines ,is provided with notches which allow you to measure the distance from an object when the distance between the target and another visible object on the same level of the observer on the horizontal line of

the glass .

10 notches is 0.9cmeach notch is 1/9cm,the distance between eyes and the

Aiming line is 12cm.

For example ,if the distance between two objects is 36m and the notches on the glass are 12 .

12CM

0.09cm

X

12 2

X =400m

400m is the distance between you and the object.

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The simple formula is 1200 X 36m ( distance between two objects)
9X 12 (quantity of the notch)

=400m

Of course ,if the distance between two objects is 36m,and and the notches on the glass are 12,and the other object is some distance from you on the same level ,and the notch is 18. 36/12*18=54m

16WARNING!

In superior quality compass the oscillation of the needle is stabilized by the liquid in which it is totally dipped(13). Strong variations in temperature or pressure can cause the formation of small air bubbles around the compass card(13) .These bubbles do not interfere with the compass functioning and they will disappear in 24-48 hours under normal temperature conditions .

Avoid anyhow to use the compass at temperatures much under 0°centigrade.

Make sure to be always far from magnetic fields created by iron parts ,magnetic cores or electric wires which cause the compass to show wrong values.

Prevent your instrument from falling or getting damaged and never tamper it (so as to keep your guarantee always

valid)

17CONTACT US

service@aofar.com

URL : www.aofar.com

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References

• AOFAR.COM --Rangefinder&Compass

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