How much error is there with an Active Prism when the gun is lower or higher in elevation? You can't tilt the Active Prism, so at what point do I set it aside and use a prism that I can tilt towards the gun?
Dave
Here are a couple of pages from my Topcon 9003 manual.
I'm sure the charts would be different with your system but this should give you some idea of the magnitude of errors in distance and angle.
Thanks, Stephen. I think I need to be concerned. It looks like the only option is to switch to a tilting prism when the angle gets steep.
Dave
The Topcon GPT does not use an active prism it is a passive prism.
I posted the Topcon info as an example. However, unless the instrument is able to compensate for the misalignment of the prism then I don't believe active vs. passive prisms will make a difference. It's all about the prism constant and the angles involved.