Pnw coast, post: 429853, member: 12522 wrote: I have had a lengthy conversation with a trimble tech about the vertical errors I've seen with the mt1000, he confessed the prism is designed for mass production topo level work (as if topo doesn't need to be accurate) not precise vertical measurements. So 5 hundredths of vertical error in 400 feet horizontal distance didn't surprise him. It's been a while since I had this conversation so I don't recall exactly his explanation, but it had to do with all the small prisms on the mt1000 are of poor geometry for the tracking on the instrument to achieve consistent accurate results and that I should be using a larger 62mm prism for accurate tracking. I didn't understand it but when I switched to the larger prism my vertical accuracy consistency improved greatly. Hope this helps.
As for the 10mm tape vs edm distance error I believe 10mm is the mt1000 prism constant so that may be a possibility. Good luck.
Thank you for the information... but the 10mm constant of the Mt1000 ia automatic when you select it on the access. I found out the problem already. It was the random tribrach that im using for my backsight. After i calibrated the tribrach it gives me exact distance between active edm mode and tape measurement.