Focusing - 1.15.4.c | 1. Measurement of Levels | Surveying and Geomatics
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Interactive Audio Lesson

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Setting the Tripod

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0:00
Teacher
Teacher

Let's start our discussion on setting up the leveling instrument. Who can tell me the first thing we do when we set the tripod?

Student 1
Student 1

We should place it on a flat, stable surface.

Teacher
Teacher

Correct! Once it's stable, we want to ensure the legs are positioned equally to form an equilateral triangle. Why do we want that?

Student 2
Student 2

So it's easier to level it quickly!

Teacher
Teacher

Exactly! Remember, when we say 'setting', think of it as 'forming a firm triangle!' Now, let's proceed to the next step...

Leveling the Instrument

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Teacher
Teacher

Now that we have our tripod set, the next step is to level the instrument. Can anyone remind me how we do that?

Student 3
Student 3

We use leveling screws to adjust the position of the circular bubble.

Teacher
Teacher

Absolutely! And why is it important to check the bubble after rotating the telescope?

Student 4
Student 4

To make sure it's consistently level from all angles!

Teacher
Teacher

Great job! Always remember to repeat this step so that our readings are accurate. Let's dive into focusing next.

Focusing the Instrument

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Teacher
Teacher

Focusing is the last step. Can anyone explain why focusing is critical when taking readings?

Student 1
Student 1

If we don't focus properly, we won't see the leveling staff clearly.

Teacher
Teacher

Very good point! We adjust both the eyepiece and objective lens. What should we watch out for during this process?

Student 3
Student 3

Different people might see the images differently, so focusing might need adjustments for each user.

Teacher
Teacher

Exactly! It's important all users can get accurate readings, enhancing our reliability in measurements. Let's summarize today’s key points.

Introduction & Overview

Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.

Quick Overview

This section outlines the importance of focusing on leveling instruments during temporary adjustments before taking measurements.

Standard

In this section, key steps for the temporary adjustment of leveling instruments are detailed, which include setting, leveling, and focusing. Each step is critical for ensuring accurate elevation measurements, making this procedure essential for successful surveying tasks.

Detailed

Focusing in Levelling Instruments

Focusing is a critical step in the temporary adjustment of leveling instruments before taking measurements. This section details the procedure which consists of three primary steps: Setting, Leveling, and Focusing.

1. Setting

The first step involves setting up the tripod stand at a height that allows for an approximately horizontal instrument placement. The legs of the tripod should form an equilateral triangle to facilitate quick leveling. The leveling instrument, secured with screws, is positioned directly above the ground station using a plumb bob for accuracy.

2. Leveling

Setting the instrument's level is next, which is achieved using leveling screws to position the circular bubble within its center. This is validated by observing the bubble's position after rotating the telescope 360 degrees. Proper leveling is crucial to ensure that readings taken reflect true elevations.

3. Focusing

Finally, the focusing of the instrument is essential for clear visibility of the leveling staff. This involves adjusting both the eyepiece and the objective lens to create sharp images of the staff being measured. Adjustments must be repeated if different observers are using the instrument since their individual vision capabilities may vary.

The focusing procedure enhances measurement accuracy and minimizes potential errors related to parallax, further emphasizing its significance in surveying tasks.

Definitions & Key Concepts

Learn essential terms and foundational ideas that form the basis of the topic.

Key Concepts

  • Setting: The initial phase of leveling where the tripod is placed correctly.

  • Leveling: Adjusting the instrument so the circular bubble sits in the center.

  • Focusing: Ensuring clarity in measurements by adjusting the eyepiece and objective lens.

Examples & Real-Life Applications

See how the concepts apply in real-world scenarios to understand their practical implications.

Examples

  • When setting a tripod, ensuring stable legs can prevent time-consuming adjustments later.

  • In focusing, if one observer adjusts the eyepiece but another user subsequently uses the level, they may require their adjustments even if the first user got it correct.

Memory Aids

Use mnemonics, acronyms, or visual cues to help remember key information more easily.

🎵 Rhymes Time

  • Set it right, level it tight, focus clear, and see the light!

📖 Fascinating Stories

  • Once upon a time, a surveyor named Al set up his tripod near a hill. He wanted to ensure it was stable, so he checked the angle, leveled the bubble, and focused his gaze. Every step led him to clear measurements on his adventure!

🧠 Other Memory Gems

  • S - Setting, L - Leveling, F - Focusing: 'SLF' can help remember the sequence.

🎯 Super Acronyms

F.L.S - Focus, Level, Set

  • Remember this order to gather accurate data.

Flash Cards

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Glossary of Terms

Review the Definitions for terms.

  • Term: Levelling Instrument

    Definition:

    A device used to measure the elevation differences between points.

  • Term: Plumb Bob

    Definition:

    A weight suspended from a string used to locate a vertical reference line.

  • Term: Circular Bubble

    Definition:

    A device that indicates levelness of the instrument.

  • Term: Telescope

    Definition:

    An optical instrument that allows the user to see distant objects more clearly.

  • Term: Eyepiece

    Definition:

    The lens at the end of a telescope that one looks through to see the magnified image.

  • Term: Objective Lens

    Definition:

    The lens that gathers light and creates an image of the subject being observed.