| record number: | 37 |
| instrument type: | self reducing tacheometer |
| manufacturer: | Carl Zeiss Jena |
| serial number: | 129597 |
| model: | Redta 002 |
| weight: | 6.60 kg |
| dimensions (l/w/h): | 30/18/30 cm |
| year of manufacture: | 1951 |
| centering and leveling the instrument: |
plumb bob
circular level toric level on the alidade coincidence vertical circle level |
The self-reducing tacheometer was made in 1951. Already at first glance, the instrument is very different from conventional tacheometers. It is a typical representative of tacheometers with double image optical distance meters. Horizontal distances are measured using the principle of a parallactic triangle with a variable parallactic angle and a variable base at the target point. The base of the triangle is determined by reading the division on a separate 210 cm long Redta horizontal staff. Alternatively, a stand that allows the height of the staff to be adjusted can be used. The collimator on the staff allows for a perpendicular positioning of the staff with respect to the line of sight.
The vertical circle has a sexagesimal division and an addition division for the tangent of the angle. It helps us calculate height differences. The precision of the distance measurements is 2 cm per 100 m and the precision of the direction measurements is 5''.
The instrument was designed primarily for polygon net measurements. Optical distance measurement has greatly simplified measurements with measuring tapes. The instrument is in its original excellent condition.
| horizontal circle | vertical circle | |
|---|---|---|
| diameter: | protected, 114 mm | protected, 74 mm |
| type of division: | engraved division | engraved division |
| limb implementation: | glass bracket | glass bracket |
| division: | sexagesimal/sexadecimal | sexagesimal/sexadecimal |
| unit: | 1° | 1° |
| Reading | ||
| number of reading points: | 1 | 1 |
| reading device: | optical micrometer | optical micrometer |
| number of units: | 60 | 60 |
| graduation unit: | 1', estimation 6'' | 1', estimation 6'' |
| repetition: | Mahler membrane | / |
| Distance measurement | ||
| principle: | double image optical distance meter – parallax triangle with variable angle and base on the horizontal staff at the target | |
| precision: | 2 cm per 100 m | |
| range: | up to 200 m, depending on the staff length | |
| Telescope | ||
| diameter of objective: | 42 mm | |
| magnification: | 25 x | |
| type: | telescope with internal focusing | |
| cross hairs/reticule: | basic horizontal and elevation hair, two distance hairs, constant 100, additional vertical hairs for measurement with a special horizontal staff | |