Important notice
The axes of the eyes of some people are not parallel, a condition called heteropho-
ria. This can even vary in time and be Downhill dependent on different factors too. There- fore, in order to be sure that said phenom- enon does not affect the accuracy of
m
20
41
5 
2
6
3
7Uphill
4
m | m | |
20 | 20 | |
19 | 19 | |
18 | ||
| ||
17 | 18 | |
16 |
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readings, it is suggested that the user checks this possibility before taking the actual readings as follows: Take a reading with both eyes open and then close the free eye. If the reading does not change
8
9
10
11
5
6
7
15 | 17 |
| |
14 | 16 |
13 |
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12 | 15 |
| |
11 | 14 |
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appreciably there is no disalignment of the
12 8
10 | 13 |
eye axes, and both eyes can be kept open. Should there be a difference in the readings, keep the other eye closed and sight halfway to the side of the instrument body. This will create an optical illusion whereby the hairline continues past the instrument body and is seen against the target.
13
14
15
16
17
18
19
20
21
9
10
11
12
13
14
15
16
9 | 12 |
8 | 11 |
| |
7 |
|
| 10 |
6 |
|
| 9 |
5 |
|
| 8 |
4 |
|
Corrected height | 7 |
| |
| 6 |
| Apparent height |
Base reading
7