You check all your settings and they are good…you measure the distance with the total station only and it matches your record distance….measure it with the LM80 in control and the distance is WAY off….

No one has any idea why this is happening….you begin to beat your  head against the wall and curse electronic data collection….

We had this happen yesterday to a customer who had picked up a TS 525 to use while their TS 415 was being repaired.

Finally it occured to us that maybe they had the telescope inverted, measuring on Face 2…..

Such was not the case…but it got me thinking…and it turns out that the instrument had been set….somehow…someway…by someone…to measure the vertical angles from the HORIZON, not the ZENITH….

The total station  understood it just fine and measured correctly…but the LM80 was expecting a zenith angle, and did not compute properly with a vertical angle of +/- 359 degrees…

On the TS415/525 keyboard…Menu>Settings>Angle…make sure it is on Zenith…not Horizontal.