Northwest NSL100B - 4.2 Stadia Measurement

7
9) After you have centered the bubble, rotate the telescope 90° so that the
telescope is positioned between the first 2 leveling screws, with the 3
rd
screw
at the front or rear of the telescope. Use the 3
rd
screw only to center the
bubble at this position.
10) Rotate the telescope another 90° and repeat your leveling procedure till
telescope is turn back to its original position. The bubble should stay at the
center now through out 360°. If the bubble does not stay at the center, the
instrument needs to be checked by a qualified technician.
11) After leveling the instrument, turn the focusing knob to focus on the
objective. Turn the knob slowly to avoid moving past a focused image.
4.2 Stadia Measurement
Your Northwest Instrument Siteline Level is equipped with a stadia reticle so
you can make distance estimates. The stadia lines are located in the reticle
as shown in Diagram 4.2A below. Sight a rod, and take readings of the
upper and lower stadia lines. Calculate the difference of two readings and
multiply by 100 to obtain the distance between the rod and the instrument.