Topcon AT-B3A 28x Automatic Level
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Shipped direct from the manufacturer
The AT-B3A is Topcon's mid-range automatic level in a family of three, rated 28x magnification and a 0.5 arc-second compensator, between the sharper AT-B2 and the softer AT-B4A.
01
This is the AT-B3A, the middle of three closely specified Topcon automatic levels
Topcon builds three automatic levels in this family: the AT-B2, the AT-B3A and the AT-B4A. An automatic level self-levels its own line of sight, using an internal compensator, a small pendulum mechanism inside the instrument. Once you have roughly set up the tripod, it keeps the crosshair level, so you are not leveling it by hand for every reading. This listing sells the AT-B3A, rated 28x magnification. The AT-B2 is sharper, at 32x. The AT-B4A is softer, at 24x. Compensator setting accuracy follows a similar split. The AT-B3A is rated 0.5 arc-seconds. The AT-B2's compensator is tighter, at 0.3 arc-seconds. Magnification and setting accuracy are the two figures worth checking before you order. These three models sit close enough in spec that it is easy to buy the wrong one.
02
Topcon states this compensator's precision two different ways, and we are not picking one
Topcon's own documents do not agree on how to describe this compensator's precision. One current Topcon specification sheet states the setting accuracy as 0.5 arc-seconds and the working range as plus or minus 15 arc-minutes. Those are the units you would expect for an angle. An older Topcon catalog states the identical two figures with the units spelled out in full instead, 0.5 in. and plus or minus 15 ft., linear units on a measurement that is fundamentally angular. Both documents are Topcon's own. We are printing both readings rather than choosing one. A compensator specified in feet is odd enough that you deserve to see the disagreement rather than a confident guess. The number itself, 0.5 against the AT-B2's 0.3, is consistent across every Topcon document that states it. Only the unit notation differs.
03
Topcon names two of the three models with an A suffix, and does not explain why
The AT-B3A and the AT-B4A both carry an A after the model number. The AT-B2 does not. None of Topcon's four current documents on this instrument, the category page, the two-page brochure, the full catalog or the regional specification sheet, explains the suffix. A handful of resellers shorten the name to AT-B3 without it, which reads as shorthand rather than evidence of an earlier, unsuffixed model. If you are matching this instrument against an internal parts list or a customer's existing kit by model number, use the full AT-B3A. That is what Topcon itself prints everywhere the model is named.
04
Accuracy over a 1 km double-run is 1.5 mm, and no micrometer option exists for this model
A 1 kilometer double-run level line is a standard test that runs a line of levels out and back to check for drift. Without a micrometer fitted, the AT-B3A is rated to 1.5 mm (0.06 in.) standard deviation over that test. A micrometer is a fine-adjustment eyepiece accessory that tightens the reading further. The AT-B2 reaches 0.7 mm without one and 0.5 mm with its optical micrometer fitted; the AT-B4A reaches 2.0 mm. Topcon's own parts list documents that micrometer accessory, the OM5, for the AT-B2 only, with no equivalent part listed for the AT-B3A. If 0.5 mm precision matters to your work, that points you at the AT-B2, not this instrument. Objective aperture is 36 mm and resolving power is 3.5 arc-seconds, two figures Topcon states only on its regional specification sheet, not its US brochure or catalog.
05
Topcon publishes no warranty term for this level; two dealers state five years
Topcon's own catalog carries a warranty row for its laser products elsewhere in the same document, spelling out a term in writing. It carries no warranty row at all for the AT-B or B Series optical levels, including this model. Two independent US dealers both state a five year manufacturer's warranty for the AT-B3A. That figure does not appear anywhere in Topcon's own material, so treat five years as a dealer claim rather than a manufacturer-published one. Call us to confirm the exact term before you order.
06
Topcon's own materials do not agree on what ships with this specific model
Topcon's two-page AT-B brochure lists a shared kit across the family. That kit is the level itself, a hex wrench, a vinyl cover, a cleaning cloth, a user manual and a hard case. It states plainly that adjusting pins ship with the AT-B2 only. A separate Topcon regional sheet shows a photographed standard package that also includes a plumb bob and a lens cap. That photograph is captioned as the AT-B2's own kit, not a list shared across all three models. Neither document confirms what ships specifically with the AT-B3A. We are not going to guess at a packing list. Call us and we will confirm exactly what is in the box for your order before you buy.
07 FOR UNIVERSITIES, COLLEGES AND GOVERNMENT AGENCIES
My Surveying Direct accepts purchase orders from universities, colleges and government agencies
My Surveying Direct is an authorized reseller, and every AT-B3A ships direct from Topcon. A few things about this listing are not yet settled in Topcon's own materials. They include the compensator's unit notation, the A suffix, the exact box contents and the warranty term. Call us before you order, +1 888 850 6533, Monday to Friday, 9 to 5 Mountain Time. We will confirm what your kit includes and where things currently stand before you buy.
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REFERENCE
Specifications
Telescope and optics
| Magnification | 28x. The AT-B2 in this family is 32x and the AT-B4A is 24x |
| Objective aperture | 36 mm (1.42 in.). The AT-B2 is 42 mm and the AT-B4A is 32 mm |
| Resolving power | 3.5 arc-seconds. The AT-B2 resolves to 3 arc-seconds and the AT-B4A to 4 arc-seconds |
| Field of view, at 100 m (328 ft.) | 1Ā°25' (2.5 m / 8.2 ft.). The AT-B2 is 1Ā°20' (2.3 m / 7.5 ft.) |
| Minimum focus | 0.2 m (7.9 in.) from the end of the telescope, or 0.3 m (1 ft.) from the instrument's center. The same figure applies to all three AT-B models |
| Image | Erect |
| Stadia | Yes, ratio 1:100, constant 0 |
| Focusing knob | 1-speed. The AT-B2 has a 2-speed focusing knob |
| Sighting aid | Peep sight, shared with the AT-B2. The AT-B4A uses a gun sight |
Accuracy and compensator
| Accuracy, 1 km double-run leveling, without a micrometer | 1.5 mm (0.06 in.). The AT-B2 reaches 0.7 mm over the same test without a micrometer, or 0.5 mm with one fitted; the AT-B4A reaches 2.0 mm |
| Accuracy, 1 km double-run leveling, with a micrometer | Not applicable. Topcon's own parts list documents an optical micrometer accessory, OM5, for the AT-B2 only, with no equivalent micrometer part for the AT-B3A |
| Compensator type | Pendulum compensator with a magnetic damping system, using four suspension wires of super-high-tensile metal |
| Compensator setting accuracy | 0.5 arc-seconds. The AT-B2 compensator is tighter, at 0.3 arc-seconds |
| Compensator working range | Ā±15 arc-minutes, the same across all three AT-B models |
Circular level and horizontal circle
| Circular level sensitivity | 10 arc-minutes of tilt per 2 mm of bubble travel, the same across all three AT-B models |
| Horizontal circle diameter | 99 mm (3.9 in.), shared with the AT-B4A. The AT-B2 in this family is 103 mm (4.1 in.) |
| Horizontal circle minimum division | 1 degree or 1 gon, selectable, read directly below the eyepiece |
Build and environment
| Water and dust resistance | IPX6 (IEC 60529:2001), protected against powerful water jets from all directions |
| Operating temperature | -20Ā°C to 50Ā°C (-4Ā°F to 122Ā°F) |
| Size | 122 mm wide x 214 mm long x 140 mm high (4.8 x 8.4 x 5.5 in.), shared with the AT-B4A. The AT-B2 in this family is 130 x 215 x 140 mm |
| Weight | 1.5 kg (3.3 lbs.), shared with the AT-B4A. The AT-B2 in this family is 1.85 kg (4.1 lbs.) |
Warranty
| Manufacturer warranty | Not stated for the AT-B Series in any Topcon document available for this model. Several US resellers of this exact instrument state a five year manufacturer's warranty; call to confirm the exact term before you buy |