Well Bill, if you go outside, set up your instrument, improperly leveled, and then double angles (for the purpose of this exercise, a doubled angle is one whereby the telescope is inverted into F2 reading a reciprocal of the original zenith angle) and repoint the instrument at the original target, you will NOT get an answer that can be divided by two (or some other method) within the tolerances of the instrument.
That's the point and the reason the barrel should be inverted on critical shots. It catches those little things.
I totally agree with that. Distance is a huge factor in what I will accept. 30" at 100', sure! 30" at 300', hell no! 🙂
I could be wrong, my friend, but I don't think repeating an angle face1 face2 will catch mis-leveling.
1
> Your idea that I consider everyone to be idiots. That's hardly true.
No, I know you said that even intelligent people do idiotic things...:-P
Just kidding, point taken.
Testing the instrument accuracy...
> Surveyors don't do this routinely (as far as I know) on every traverse, but it is a good instrument check (as long as you can turn the same angle all the time).
Check out the multiple threads "TS direction accuracy Chapters 1-6" (I think that's how many there are, lol!)
Been there, Done that! My instrument is good.
Now all we need is a foolproof way to test the operator.:-D
Those who have been around this and the other forum for a few years will recall that many of us were declared "dippy idiots." RIP Richard.
One thing that doubling the angle using both faces does for you is to average out the effects if the horizontal axis (vertical motion) is out of adjustment and not perpendicular to the vertical axis (horizontal motion). This is most important when shooting BS and FS targets which are at different elevation angles.
Another benefit, of course, is averaging out some of the error in the graduated circle.
It does not have anything to do with leveling. If you take an instrument in good adjustment and throw it seriously out of level, the Face1 and Face2 measurements will still agree even though the angles have significant error.
> As far as I know, we still don't know what his targets are. If it's a short sight to a prism pole 40" isn't that much - only 0.02' at 100' and of course proportionately less at shorter ranges.
My targets are all identical Topcon Prisms with zero offset, mounted on three leg Topcon instrument tripods with tribrachs. One has an optical plummet; the other I use a plumb bob in the tribrach, level the tribrach and mount the prism.Distances vary.
Do the prisms have targets around them? What feature do you sight on to assure repeatability?
> Do the prisms have targets around them? What feature do you sight on to assure repeatability?
Absolutely.
I have big targets:
I know now that You can't focus on the prism center, because if the prism is not absolutely aimed at the instrument (depending on the offset used), you will get centering errors.
The targets are in the plane of the station. I focus on the target "arrows".
I don't think that's contributing to my issue.
How far are your sight distances?
Testing the instrument accuracy...
No I don't do that but it may be the only way to use all parts of the circle on most total stations.
My S6 will turn 4 sets automatically faster than I can do two manually.
"idiotic"
> Actually, perfectly intelligent people do perfectly idiotic things from time to time. It's to be avoided, though. Look at it this way: at least he wasn't laying down in the center of a county road. :>
My sister is a Doctor; she graduated Summa Cum Laude.
I saw her slam her own head in a car door when we were kids....:pinch:
Shawn - I'm pretty sure this thread is a supplement to this one-> [msg=288201]he's having problems with angular closure[/msg]
Have an assistant point that prism directly at the gun and while you are looking at it slowly turn it. You should be able to see if that be the problem.
My suspicion is short sights where the 40" is relatively insignificant in the sight distance. Determine the significance of your sighting error by applying it to the distance sighted.
I have never liked those target surrounds. I prefer to sight the little dimple on top at short distance and the mass of the prism for long distance. A second reason I don't like them is if you don't lock the target, a good Colorado wind will spin them. If you do lock them, a gust could knock your set-up off or even sometimes slam it to the ground.
Testing the instrument accuracy...
> No I don't do that but it may be the only way to use all parts of the circle on most total stations.
>
> My S6 will turn 4 sets automatically faster than I can do two manually.
:good:
and give you the residuals before you accept the mean...
> Those who have been around this and the other forum for a few years will recall that many of us were declared "dippy idiots." RIP Richard.
hear-hear :drink:
Testing the instrument accuracy...
Yes it's a beautiful thing. I open each observation and look at it.
Really the only time it looks bad is when some bonehead gets in its way and it gets a shot to my vest.
"idiotic"
> I saw her slam her own head in a car door when we were kids....:pinch:
In my opinion, it's only idiotic if she did it on purpose.:-)