"Has anyone out there have info on R.Poulin, Albert Lepetit, E. Maubant? MapTack"

"I've managed to get my Wild TC2000 to return a distance with the prism that came with my DI10 and also with a Kern DM500 prism so I know that I can take mesurements with the Kern ones. What is the test you mention? Will I find references to it in any books?"

"I know that the 500 series prism works with other EDM's but I do not have the addition constant. The 500 series prism was designed to work with an EDM with the transmitter vertically aligned with the receiver optics whereas most other units are aligned side by side in a horizontal plane. I don't know if short distances would be affected by this change of geometry. I presume longer range distances would be OK. To find out you would have to carry out the A-B-C addition constant test & at different ranges."

"Thanks for the contacts, I'll give them a try. Swisstek have been helpful with information already but I hadn't heard of the other two. The original price of these instruments, compared with their value now, is amazing. I guess that is progress..."

"I think they must both (I have two, one with a horizontal circle) be the later ball&socket type as the trivet (?) is different from that in this photo. Thanks for the tip about the tripods. One for a Kern level went a few weeks ago for £125 which is too much for me but it may have been the earlier type. Thanks for all your help. I hope you don't mind answering a novice's questions!"