Wouldn't you have to be shooting over a quarter mile to get that kind of difference from curvature?
I have run all the collimation routines, no surprises found there.
I use very carefully calibrated telescoping poles with 6' vials and bipods; I'm confident that my HT's are closer to reality than my HI's as measured on the slant & converted.
I have the same issue when I use the Leica GPH1 prism holders for FS & BS and tip the glass vertically to match the inclination of the line of sight. The majority of the zenith angles are within a couple of degrees of horizontal anyway.
I've compared measurements directly from the gun with those saved by the collector and they've matched- on the few times I've compared them.
SurvCE is not correcting for earth curvature, and anyway can earth curvature make 0.05' difference in a 400' line?
I'll check out some of the suggestions next time I'm in the field and report back.
Thanks for all the attention!
SS
For what it's worth, I use a TCRA1102plus with SurvCE v1.6 (I think) on an Allegro CX. I always carry elevations, and rarely miss my backsight vertical by more than 0.01 foot, usually half that. So I think your problem is likely to be a setting rather than an equipment limitation.
The 'ridiculous' was in reference to the amount of correction it applied. They both assumed the offset from center to be about a foot...
Ahh...the old tilting prism.... I think you are on to something there. I agree with Bill on the curvature thing. If you are always getting a 0.03' difference, it isn't a function of distance making it smaller or larger. It's something that is making you aim 0.03' different every time. The target not being at the same vertical location as the center of prism would create that. I bet you guys got it.
The ATR collimation being out of adjustment would be by far the most likely cause of this if distance has no affect on error amount. Run the ATR collimation routine to your 360 prism (with one of the yellow arrows facing the instrument)at 300-400 ft. Take at least 3 D and R shots in the procedure so that you get a realistic error approximation of 0-2 seconds. Compare old values to new and make sure you save the new values. If that doesn't fix it, have a good survey equipment shop that understands Leica's check it out.
:gammon:
One box to be aware of with SurveCe is the "use reciprocals" option in the set up screen, doing so will use your backsight shot to calculate a adjusted elevation to the occupy point.
This does not speak directly to your query but is a good thing to know about.
Are you solid on the columnation routine on the Leica? I was turned around on it for a while and the manuals can be a little hard to follow.
If you are using a rod that has the height imprinted on the side and is matched to the prism then maybe the tip has worn down and the height of rod is no longer correct. We have had this problem with the Swiss style CST prism poles. The fix is to replace the tip or measure the HR