Description
The Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1) is a 360° prism made by Topcon and also sold under the Sokkia brand (part number 1004684-01 (1004684-01-SURSK); Aptella SKU CTP1-A).
Its absolute prism constant is -7.0 mm, which is +27.4 mm on the Leica scale.
Specifications
| Model: | Builder Series 360 Prism |
| Manufacturer: | Topcon |
| MPN: | 1004684-01 (1004684-01-SURSK); Aptella SKU CTP1-A |
| Status: | Current |
| Height Offset: | 87.0 mm |
| Absolute constant: | -7.00 mm |
| Leica constant: | +27.40 mm |
| Constant source: | Manufacturer documentation |
| Mount: | 5/8" Thread |
| Equivalents: | ATP1 (Hayes: 'use ATP1 model' in software) |
| Last verified: | 21/10/2026 |
Sources
Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1) FAQ
Below is a list of frequently asked questions about Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1).
What is the prism constant for the Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1)?
The absolute prism constant for the Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1) is -7.0mm. The Leica constant is 27.4mm.
Can I use the Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1) with a Leica instrument?
Yes, just set the prism constant to 27.4mm.
What is the height offset of the Topcon Builder Series 360º Prism (also sold as 360 Prism Construction Series CTP1)?
The height offset is 87.0mm.
