collimation error.pdf

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Chapter 12 Collection Procedures for the Leica DNA 10 Digital level Digital Level Data Collection ........................................................................................... 12-2 Required Equipment and Material ................................................................................... 12-2 Instrument and Tripod Setup ........................................................................................... 12-2 Job Setup ....................................................................................................................... 12-3 Collimation Error Correction ............................................................................................ 12-8 Check and Adjust (Peg Test) Procedures ....................................................................... 12-9 Line Leveling ................................................................................................................. 12-17 Setup ..................................................................................................................... 12-17 Starting the Run ..................................................................................................... 12-22 Check Shots ........................................................................................................... 12-26 Allowable Misclosure .............................................................................................. 12-29 Warning Messages ................................................................................................ 12-32 Interesting New Topics in this Chapter Multiple check and adjust procedures (peg tests) for correcting collimation errors. How to set up a leveling job prior to beginning a run. How to calculate the allowable misclosure on a level line or loop. How to correct a measurement when warning messages are displayed.

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Chapter 12

Collection Procedures for

the Leica DNA 10 Digital level

Digital Level Data Collection ........................................................................................... 12-2

Required Equipment and Material ................................................................................... 12-2

Instrument and Tripod Setup ........................................................................................... 12-2

Job Setup ....................................................................................................................... 12-3

Collimation Error Correction ............................................................................................ 12-8

Check and Adjust (Peg Test) Procedures ....................................................................... 12-9

Line Leveling ................................................................................................................. 12-17Setup ..................................................................................................................... 12-17Starting the Run ..................................................................................................... 12-22Check Shots........................................................................................................... 12-26Allowable Misclosure.............................................................................................. 12-29Warning Messages ................................................................................................ 12-32

Interesting New Topics in this Chapter

Multiple check and adjust procedures (peg tests) forcorrecting collimation errors.

How to set up a leveling job prior to beginning a run.

How to calculate the allowable misclosure on a level lineor loop.

How to correct a measurement when warning messages aredisplayed.

Collection Procedures for the Leica DNA 10 Digital Level

12-2 Revised April, 2009

Digital Level Data CollectionThe Leica DNA 10 level is the latest digital level utilized by WYDOT. These levels began replacingthe older Leica NA2002 digital levels in 2004. This chapter deals exclusively with the DNA 10level. The previous edition of chapter 12, which provides instructions for the NA2002 level, canstill be accessed by clicking on the “Previous Chapter Editions” link.

There are several advantages inherent with digital levels:

Typically, readings can be taken faster with a digital level than with an optical level.

Increased accuracy can be achieved by taking and averaging multiple readings.

Human errors associated with reading and recording observations are eliminated.

The observation data is stored on an internal memory card. After the level line or loop has beencollected, the data can be transferred from the memory card and saved as a .GSI file on a desktopcomputer. This file along with a copy of the field notes can be submitted to the State Photogrammetryand Surveys Engineer. Refer to Chapter 13 in this manual for more information on transferring surveydata. Once the Photogrammetry and Surveys (P&S) Section receives the level data, it will beprocessed using Leica’s Geo Office (LGO) software.

Required Equipment and MaterialDNA 10 digital level

Battery and battery charger

Internal memory card

Fixed legged tripod

Bar coded level rod

Field book

Temporary turning point platform (Turtle)

1" x 1" wooden hubs or railroad spikes (used for the peg test)

Instrument and Tripod SetupPlace the digital level on the tripod. Tighten the central fixing screw to securely fasten the level tothe tripod. Turn the tribrach foot screws to their middle positions. Set the tripod such that the tripodplate is as level as possible. Using the foot pegs on the tripod, firmly press the points into the ground.Center the circular bubble by adjusting the foot screws.

Chapter 12

Revised April, 2009 12-3

Figure 12-1. Instrument and tripod setup.

Job SetupTurn on the DNA 10 by pressing the On/Off key.

Figure 12-2. DNA 10 keyboard and display screen.

Collection Procedures for the Leica DNA 10 Digital Level

12-4 Revised April, 2009

Figure 12-3. Program and Enter key.

To start a new job press the PROG key. At the PROGRAMS menu, use the yellow navigation keys toscroll down to option 2, LINE LEVELLING and press the red Enter key or just press the 2 digit key.

Figure 12-4. Navigation keys.

Chapter 12

Revised April, 2009 12-5

Figure 12-5. PROGRAMS menu.

At the LINE LEVELLING menu, create a new job. Highlight option 1, Job and press the Enter key orpress the 1 digit key.

Figure 12-6. LINE LEVELLING menu.

Collection Procedures for the Leica DNA 10 Digital Level

12-6 Revised April, 2009

At the SELECT JOB menu, use the navigation keys to highlight NEW, then press Enter.

Figure 12-7. SELECT JOB screen.

At the NEW JOB menu, type in the job name (up to 16 characters). Use the white SHIFT key toalternate between numerical digits and alphabetical letters which includes special characters. Afterkeying in the job name, press Enter and key in the operator’s name or initials. Press the Enter key anduse the navigation keys to scroll down to highlight SET, then press Enter. The message Job Set! willbe briefly displayed.

Figure 12-8. NEW JOB screen.

Chapter 12

Revised April, 2009 12-7

At the LINE LEVELLING menu, use the navigation keys to scroll down and highlight END, then pressthe Enter key.

Figure 12-9. New job created.

Collection Procedures for the Leica DNA 10 Digital Level

12-8 Revised April, 2009

Collimation Error CorrectionThe collimation error is the vertical angle between the actual line-of-sight and the ideal horizontalline.

Figure 12-10. Collimation error ( ).

With the DNA 10, optical and electronic collimation errors can occur. Staff readings areautomatically corrected for the electronic collimation error and stored in the instrument. Opticalcollimation errors are eliminated by adjusting the reticle (cross-hairs) with the ocular (eye-piece).

A CHECK & ADJUST (Peg Test) is performed to determine the collimation error and should beconducted at the job site and on a regular basis. At a minimum, a peg test should be performed in thefollowing situations:

Prior to starting a new job

At the beginning of each week, even when working on the same job for more than oneweek

When there is an ambient temperature change of +/- 30 deg F

Any time the level has been dropped or significantly jarred

Follow the instructions on pages 9 through 16 to perform a CHECK & ADJUST (Peg Test)procedure.

Chapter 12

Revised April, 2009 12-9

Figure 12-11. PROGRAMS menu.

In the CHECK & ADJUST menu, the job that was previously created should be active. Select option2, Meth.

Figure 12-12. Peg test method.

Check and Adjust (Peg Test) ProceduresAt the PROGRAMS menu, select option 4, CHECK & ADJUST.

Collection Procedures for the Leica DNA 10 Digital Level

12-10 Revised April, 2009

Use the left or right navigation keys to select a peg test method, A x Bx or A x x B.

Figure 12-13. Selecting a peg test method.

The Stf1 and Stf2 lines should be left blank. Press Enter to highlight SET, and press Enter again to setthe method. The message Method Set! will be briefly displayed.

Figure 12-14. Setting the peg test method.

Chapter 12

Revised April, 2009 12-11

Place 1" x 1" wooden hubs or railroad spikes at stations A and B. The distance between A and B is 30meters. When performing a peg test, choose a site with level terrain.

Figure 12-15. A x Bx method.

Place 1" x 1" wooden hubs or railroad spikes at stations A and B. The distance between A and B is 60meters. When performing a peg test, choose a site with level terrain.

Figure 12-16. A x x B method.

Collection Procedures for the Leica DNA 10 Digital Level

12-12 Revised April, 2009

At the CHECK & ADJUST menu, select option 3, START and press the Enter key to begin the peg test.

Figure 12-17. Start the peg test.

At the CHECK & ADJUST screen, press the Enter key to continue.

Figure 12-18. First instrument setup (station 1).

Chapter 12

Revised April, 2009 12-13

With the DNA 10 set in position 1, aim the instrument at the level rod located at station A. Ifnecessary, adjust the focusing knob to focus clearly on the rod, and press the red measure button on theright side of the instrument. The DNA 10 will then take and average three readings for eachmeasurement.

Figure 12-19. Measure button.

Collection Procedures for the Leica DNA 10 Digital Level

12-14 Revised April, 2009

After the measurement has been taken, record the rod reading and distance for A1 in the field book.Accept the measurement and continue by pressing Enter. The rod person will now move to station B.Aim the DNA 10 at station B, focus the instrument (if needed), and press the measure button.

After the measurement has been taken, record the rod reading and distance for B1 in the field book.Accept the measurement and continue by pressing Enter.

Figure 12-20. Peg test measurements at station 1.

At the CHECK & ADJUST screen, press the Enter key to continue.

Figure 12-21. Second instrument setup (station 2).

Chapter 12

Revised April, 2009 12-15

The rod person will stay at station B and the instrument person will move to position 2. When thesetup is complete, aim the DNA 10 at station B. Focus the instrument on the rod, and press themeasure button. After the measurement has been taken, record the rod reading and distance for B2 inthe field book. Accept the measurement and continue by pressing Enter.

The rod person will now move back to station A. Aim the DNA 10 at station A, focus the instrument(if needed), and press the measure button. After the measurement has been taken, record the rodreading and the distance for A2 in the field book. Accept the measurement and continue by pressingEnter.

Figure 12-22. Peg test measurements at station 2.

Collection Procedures for the Leica DNA 10 Digital Level

12-16 Revised April, 2009

The collimation results will be computed and displayed as seen in figure 12-23. The differencebetween the old and new collimation errors should not be greater than 15" +/-. If the difference isgreater than 15"+/-, another peg test will need to be performed. If the 2nd peg test is still greater than15" +/-, the instrument may need to be calibrated by a Leica vendor.

Figure 12-23. Collimation results.

When the difference is within the 15" tolerance, note all of the collimation information in the fieldbook. Press Enter to set the new collimation value in the instrument. The message New CollimationSet! will be briefly displayed. At this point the instrument should be at the PROGRAMS menu.

Chapter 12

Revised April, 2009 12-17

Line LevelingLine leveling is a series of backsight and foresight readings that can be accomplished with aninstrument person and a rod person. A level line is started at a point with a known elevation and runsthrough a series of points with unknown elevations. The line will end at another point with a knownelevation. A level loop begins at a point with a known or assumed elevation, runs through a series ofpoints with unknown elevations, and returns to the original starting point.

SetupAt the PROGRAMS menu, select option 2, LINE LEVELLING and press Enter. The job should still beset. To create a new line, scroll down and highlight option 2, Line and press Enter.

Figure 12-24. Create a new line.

Collection Procedures for the Leica DNA 10 Digital Level

12-18 Revised April, 2009

A line name of up to 16 characters can be entered. Once the line name has been keyed in, press Enter.The Meth line should always read BF (a backsight shot followed by a foresight shot). Enter a pointname in the Pt ID line. This is the point that the level run is starting from and can be a benchmark,project control monument, or flight line target. Examples of point names are LABS 01, LACC 83A,WYDOT 03, or B 67.

Point names with numbers less than ten should be entered into the instrument with a leading zero, i.e.LACC 01, LACC 02, LACC 03, etc. The instrument will then correctly sort these point names innumerical order when the point list includes point numbers higher than ten. The Pt ID line only allowseight characters. Point names with eight or more characters will have to be abbreviated or spaces mayhave to be omitted (e.g. LNAS125A, A67Reset).

After the Pt ID line has been keyed in, press the Enter key. The H0 line will now be highlighted. TheH0 line is the elevation of the starting point. This elevation should be entered in meters. If assumingan elevation, use 1000 m. Scroll down until SET is highlighted and press the Enter key. The messageLine Set! will be briefly displayed.

Figure 12-25. Set a new line.

Chapter 12

Revised April, 2009 12-19

From the LINE LEVELLING menu, select option 3, Set, and press the Enter key.

Figure 12-26. Set tolerances.

Use the navigation keys to set the Precise line to Off and the other lines to On. Scroll down andhighlight LIMITS and press the Enter key.

Figure 12-27. Tolerance settings.

Collection Procedures for the Leica DNA 10 Digital Level

12-20 Revised April, 2009

At the Enter TOLERANCES screen, change the tolerances to the values shown in Figure 12-28. Scrolldown and highlight SET and press the Enter key. Select SET one more time at the SET TOLERANCESscreen and press Enter to accept the changes. The message Tolerances Set! will be briefly displayed.For more information on digital level standards, refer to the WYDOT Survey Manual, Section IX,Survey Standards.

Figure 12-28. Tolerance values.

At the LINE LEVELLING menu, the START/ CONT line will be highlighted, press the Enter key tostart the level run.

Figure 12-29. Start the level run.

Chapter 12

Revised April, 2009 12-21

Before the new line is started, a CHECK LIST menu will be displayed. Verify that the settings are thesame as shown in Figure 12-30. If these values need to be edited, press the MODE key. Change thenecessary settings and press the Enter key when SET is highlighted.

Figure 12-30. CHECK LIST settings.

Collection Procedures for the Leica DNA 10 Digital Level

12-22 Revised April, 2009

Starting the RunFigure 12-31 is the first screen of the level run. The point name is the benchmark, project controlpoint, or flight line target at the start of the run. Always enter the point designation in the Pt ID lineinstead of the Rem line. The H line is the elevation entered in Figure 12-25.

Figure 12-31. LINE LEV screen.

To begin the run, the rod person will place the level rod on the starting point. The instrument personwill start pacing towards the next point in the run. The instrument should be placed as far from thestarting point as possible to minimize the number of turns without exceeding the 70 m maximumdistance. However, the instrument person must also consider the requirements of sighting below thetop of the level rod and a minimum of 0.3 m above the bottom of the rod. This is particularlyimportant when working in hilly terrain. Once the DNA 10 is set up for the first measurement, aim theinstrument toward the level rod on the starting point. Focus on the level rod, and press the measurebutton. Once the measurement is taken, the DNA 10 will store the backsight reading and is now readyfor the foresight reading

The instrument person will remain in the same location as the rod person paces the distance to theinstrument. The rod person will then place the turning plate (turtle) the same distance past theinstrument. After the foresight measurement is taken, the rod person will stay in the same positionwithout picking up the turtle. The instrument person will move past the rod person to setup theinstrument and take the next backsight shot. This “leap frog” procedure continues until the level run iscomplete.

Chapter 12

Revised April, 2009 12-23

Balancing the backsight and foresight distances is referred to as the distance balance. The distancebalance is calculated by the DNA 10 for each backsight/foresight combination. A running total of thedistance balance is computed by subtracting the foresight distance(s) from the backsight distance(s).This distance balance should not exceed 5 m and should be kept as close to zero as possible for eachbacksight/foresight combination and for the cumulative backsight/foresight distances. Keeping thesight distances balanced reduces earth curvature and atmospheric refraction errors. Additionally, itminimizes errors due to the instrument’s line of sight differing from a true horizontal line. These lineof sight errors are caused by internal instrument mis-adjustments and imperfectly leveled instrumentsetups. The distance balance should be corrected by the rod person on the foresight measurement only.After the foresight measurement is taken, the TBal line will show a distance balance value, see Figure12-34. If the distance balance is less than the set tolerance value, then the instrument person can moveto the next setup.

Important: If the instrument is disturbed before the foresight shot has been taken and the backsight isnot available, the run will need to be restarted. If the turning point is disturbed before the backsightmeasurement has been taken, the run will also need to be restarted. A new level line will need to becreated when starting over at the last benchmark, control point, or flight line target. Any problemsencountered during the level run should be noted in the field book.

A useful function of the DNA 10 is the test measurement mode. Measurements can be taken in thismode without storing the data. This mode is intended to optimize target distances. Test measurementsare always single measurements regardless of the current measuring mode.

To set the test measurement mode, press the SHIFT key, then the USER key to access the FUNCTIONSmenu.

Figure 12-32. SHIFT and USER/FNC keys.

Collection Procedures for the Leica DNA 10 Digital Level

12-24 Revised April, 2009

At the FUNCTIONS menu, select option 1, Test Measurement. Once the measurement has been taken,the display will show the rod reading and the distance to the rod. Any number of test measurementscan be made and the results viewed. When the optimum distance is achieved, press Enter while QUITis highlighted. The display screen will go back to the LINE LEV screen to resume the level run.

Figure 12-33. TEST MEASUREMENT screen.

Figure 12-34 is the LINE LEV screen for a backsight measurement. This screen shows several keyvalues of the current run. The dH T value is the difference in elevation from the start of the run to thelast foresight location. The H value is the elevation at the last foresight location. The TBal value isthe difference in the cumulative backsight and foresight distances.

Figure 12-34. Backsight measurement.

Chapter 12

Revised April, 2009 12-25

Figure 12-35 is the LINE LEV screen for a foresight measurement. This screen also shows severalkey values of the current run. DTot is the distance of the current run. The LDst value is the distance ofthe last backsight measurement. The TBal value is the distance required for the foresight measurementto balance the cumulative backsight and foresight distances. The TBal value is the sum of the LDst andthe TBal value from the backsight screen (Figure 12-34).

Figure 12-35. Foresight measurement.

Figure 12-36 is the LINE LEV screen before the foresight is taken when approaching a benchmark,project control point, or flight line target. As mentioned earlier, the designation should be entered inthe Pt ID line. Press the SHIFT key to select numerical digits or alphabetical letters and specialcharacters.

Figure 12-36. Entering a point ID.

Collection Procedures for the Leica DNA 10 Digital Level

12-26 Revised April, 2009

Once the foresight shot on a benchmark or control point has been stored, continue the line toward thenext point or complete the loop by returning to the starting point. The instrument person will move to anew location to take a backsight while the rod person stays at the benchmark or control point.

Check ShotsWhile on the way back to close the loop, use several of the control points or flight line targets thatwere previously collected as a check. These check shots or intermediate shots, are also known as sideshots. The purpose of the check shot is to verify that a level “bust” has not occurred somewhere alongthe run. When the instrument is ready for the foresight reading, the rod person will set the rod on thecheck point. After the check shot has been taken, continue with the run by taking the foresight.

When taking a side shot, make sure the low and high staff readings are within set tolerances. Since thecheck shot will not affect the distance balance, the distance to the side shot does not matter as long asit is less than the maximum set distance.

To perform a side shot press the INT button.

Figure 12-37. INT key.

Chapter 12

Revised April, 2009 12-27

At the INTERMEDIATE screen, enter the point ID in the NEXT line then press the Enter button.

Figure 12-38 INTERMEDIATE screen.

After the shot has been taken, the rod reading, distance from the instrument to the rod, and the checkpoint elevation will be given. The point elevation on the screen should be recorded in the field bookalong with a brief explanation of the shot. Once the values have been noted, and QUIT is highlighted,press the Enter key. The instrument will return to the line leveling screen. The rod person can thenmove to the next foresight shot.

Figure 12-39. Intermediate (side shot) measurement.

Collection Procedures for the Leica DNA 10 Digital Level

12-28 Revised April, 2009

Continue taking backsight and foresight shots until the end of the level line or the starting point of thelevel loop is reached. On the last instrument setup, the instrument person will pace the distance fromthe rod person to the ending benchmark or control point. The instrument person should then split thisdistance for the final setup. Minor adjustments may have to be made to keep the cumulative distancebalance under the set tolerance. After the final backsight has been taken, type in the point name. Whenthe foresight measurement has been taken, record the elevation of the ending point in the field book.To end the level loop, scroll down to highlight END and press the Enter key.

Figure 12-40. Ending the level run.

Chapter 12

Revised April, 2009 12-29

Allowable MisclosureBased on the total distance of the loop, the allowable misclosure can be calculated to determine if thelevel loop misclosure is acceptable.

To view the total distance of the completed line, press the DATA key.

Figure 12-41. DATA key.

At the DATA MANAGER menu, select option 1, VIEW / EDIT DATA.

Figure 12-42. DATA MANAGER menu.

Collection Procedures for the Leica DNA 10 Digital Level

12-30 Revised April, 2009

At the VIEW / EDIT DATA menu, select option 1, MEASUREMENTS.

Figure 12-43. VIEW / EDIT DATA menu.

Use the navigation keys to select the current job and level line. When these have been selected,highlight VIEW and press Enter to load the line data.

Figure 12-44. VIEW MEASUREMENT screen.

Chapter 12

Revised April, 2009 12-31

In the upper right corner of the screen is a page number. This number is the first page of the level line.

Figure 12-45. First page of the level line.

Press the left navigation key to scroll to the last page. There are several parameters listed on thispage. The DTot value is the total distance for the entire line. This is the distance value used tocompute the allowable misclosure.

Figure 12-46. Last page of the level line.

Collection Procedures for the Leica DNA 10 Digital Level

12-32 Revised April, 2009

Use the following equation to calculate the allowable misclosure for the loop or line:

allowable misclosure (meters) = .008 m x /(total distance in kilometers)

Example: The starting elevation of control point CRHA 22 is 995.509 m and the ending elevation ofCRHA 22 after closing the loop is 995.511 m. The total distance of the level loop is 1831.119 m.

First, the total distance needs to be converted to kilometers.

1831.119 m / 1000 m/km = 1.831119 km

allowable misclosure (meters) = .008 m x /1.831119

= .008 m x 1.3532

= .0108 m or 10.8 mm

Since the allowable misclosure for this level loop is 0.0108 m (10.8 mm) and the difference betweenthe two elevations is .002 m ( 2.0 mm), then the level loop closed within the acceptable tolerance. Ifthe level loop did not close within the acceptable tolerance, then the entire loop would need to be re-run until the misclosure is within the allowable misclosure.

Warning MessagesWhen a warning message is displayed, it is usually due to one of the preset tolerances being exceeded.Use the navigation keys to scroll down and highlight IGNORE, then press the Enter key. This acceptsthe error and enables the operator to correct it. Press the SHIFT key and then the Back navigation keyto retake the measurement, see Figure 12-48

If the REMEAS option is selected, the instrument will disregard the last measurement taken. If the lastmeasurement was a backsight and the turning point is no longer available (i.e. the turtle has beenmoved) the run will need to be restarted at the last benchmark, control point, or photo target. Alwaysselect the IGNORE option when a measurement needs to be retaken.

Note: When performing a check shot, no warning messages will be displayed. However, when thesemeasurements are taken, the preset tolerance values should not be exceeded. Refer to Figure 12-28 forthese values.

Chapter 12

Revised April, 2009 12-33

Figure 12-47. Rod reading warning message.

Figure 12-48. SHIFT and Back keys.

Meas. below limit! is a warning message indicating the rod reading is below the tolerance set for alow staff reading. When this message is displayed, highlight IGNORE and press Enter. Press theSHIFT key then press the Back navigation key.

Collection Procedures for the Leica DNA 10 Digital Level

12-34 Revised April, 2009

The DNA 10 will display a Remeasure Back? or Remeasure Fore? message with the point name.Press Enter while YES is highlighted. Make the appropriate adjustment to the instrument for abacksight or the turning point for a foresight and take the measurement again. The instrument may bemoved to correct an error whenever the LINE LEV screen displays the BACK command for a backsightshot, refer to Figure 12-34.

The turning plate (turtle) may be moved to correct an error whenever the LINE LEV screen displaysthe FORE command for a foresight shot, refer to Figure 12-35.

Figure 12-49. Remeasure Back? message.

Figure 12-50. Remeasure Fore? message.

Chapter 12

Revised April, 2009 12-35

Distance Bal. too big! is a warning message that the cumulative backsight/foresight distance balanceis larger than the tolerance set for the total distance balance. If the value is positive then thecumulative backsight distances are greater than the cumulative foresight distances. If the value isnegative then the cumulative foresight distances are greater than the cumulative backsight distances.To correct the error, highlight IGNORE and press Enter. Press the SHIFT key then press the Backnavigation key.

Figure 12-51. Distance balance warning message.

During the level run, the maximum TBal distance is set to 5 m. This may be exceeded with a positiveor negative value. If the value is positive then the cumulative backsight distances are greater than thecumulative foresight distances. If the value is negative then the cumulative foresight distances aregreater than the cumulative backsights.

Collection Procedures for the Leica DNA 10 Digital Level

12-36 Revised April, 2009

Any adjustments to the distance balance should be made when the instrument is ready for a foresight.If the TBal is a negative value, the rod person should move towards the instrument, thereby reducingthe foresight distance. If the TBal is a positive value, the rod person should move away from theinstrument, thereby increasing the foresight distance. As long as the backsight and foresight distancesremain balanced within the 5 m tolerance, the level process may continue.

Figure 12-52. Total distance value.

Meas. Dist too big! is a warning message that the measured distance is larger than the tolerance set forthe maximum allowable distance. When this message is displayed, highlight IGNORE and pressEnter. Press the SHIFT key then press the Back navigation key. To correct this error, move theinstrument closer to the rod for a backsight shot or move the rod closer to the instrument for a foresightshot.

Figure 12-53. Measurement distance warning message.

Chapter 12

Revised April, 2009 12-37

The warning messages in Figures 12-52 and 12-53 occur only if the Precise tolerance mode is set toOn. When these messages are displayed, select IGNORE then press the Enter key. The shot does notneed to be re-taken. The Precise tolerance mode should be switched to Off before continuing with therun.

Figure 12-54. Precision mode warning message.

Figure 12-55. Precision mode warning message.