Prism carriers with level bubble

The optical plummet should be on a rotating prism adapter and not on the tribrach. That way if you sight the point through the optical plummet and then rotate the adapter you can check if you are still centered no matter what the bubble says.?ÿ?ÿ

Posted by: not my real name

?ÿThat way if you sight the point through the optical plummet and then rotate the adapter you can check if you are still centered no matter what the bubble says.?ÿ?ÿ

this method wouldn't tell you though if you were plumb over the point. You could be rotating the adapter through a plane that isn't directly plumb over the point.

Sorry, but, I don't agree. Level up and sight the point through the optical plummet on the adapter. Rotate the adapter 180 degrees and sight again. If you are not on the point then move halfway until all rotations of the adapter show the centered point. If your optical plummet is on the tribrach you have no way of telling that it is level and plumb from that one position. none of my tribrachs have optical plummets for that reason.

its a great point you make. With your set?ÿ up you can self check things

Thank you. The picture I posted is a stock photograph from Google, but, it's the type of adapter I have and use. I'm sure your equipment manufacturer has a similar design. A bonus feature of the type of adapter I use is that the target height above the tribrach is calibrated to be the same as that of the instrument. That makes swapping one to the other easier for determining elevation.

Posted by: not my real name

Sorry, but, I don't agree. Level up and sight the point through the optical plummet on the adapter. Rotate the adapter 180 degrees and sight again. If you are not on the point then move halfway until all rotations of the adapter show the centered point.

The procedure you are describing removes the error caused by the plummet not being perpendicular to the rotational plane of the carrier and has nothing to do with level.?ÿ If you rotate a plummet and the cross hairs move then the plummet is out of adjustment.?ÿ That is how you adjust a tribrach's optical plummet.

I am trying to illustrate the value of a rotating tribrach adapter with an optical plummet. If you rotate a tribrach adapter that does not have an optical plummet on it you have no way of knowing if you are set on the point or not. All you can do is assume your tribrach is in adjustment with the latter.

Posted by: not my real name

I am trying to illustrate the value of a rotating tribrach adapter with an optical plummet. If you rotate a tribrach adapter that does not have an optical plummet on it you have no way of knowing if you are set on the point or not. All you can do is assume your tribrach is in adjustment with the latter.

I use tribrach's with optical plummets all the time. They can easily be checked with the instrument optical plummet and level or else with a tribrach adjusting cylinder, there is no assuming that the tribrachs are in adjustment. Having used both methods I can say there really is no tangible difference just different equipment adjustment procedures.

You are correct in thinking that a separate rotating carrier with plummet an level vile let you check your adjustment in the field.?ÿ I was just pointing out that you are not actually check level with procedure you quoted.

It doesn't matter which section of the setup has the bubble on it.?ÿ The way you're describing it the Precise Carrier you referenced could be out of adjustment and you'd never know it either.?ÿ The only way to be sure is to periodically adjust all of your equipment and treat them with care between adjustments.

Ron,

If your carrier has a vial bubble then you can go old school to adjust up.?ÿ Just like the days before electronic compensators.

You can also use the SECO bubble adjuster 2002-00 at each setup to do the same.

I don't. I simply keep my tribrach tuned and/or checked regularly and check shot to my back sites to see if anything has affected the setup change out?ÿ

This proceedure keeps me inside a mm.