Anybody have a rule of thumb for distance adjustment to a non-tilting prism? Something like "20 deg. slope add 0.03'" ? thanks
> Anybody have a rule of thumb for distance adjustment to a non-tilting prism? Something like "20 deg. slope add 0.03'" ? thanks
Maybe I'm way off here, but if the canter of the prism is level and over the target, and the instrument can shoot it, why would there be an adjustment?
Never used such a correction, seldom shot high vertical angles. Might take some testing using different prisms to check slope distances, Vertical angles used to reduce to horizontal may need some tweaking, depending on distance and what was used as an aiming point. Like my tilt prism but still use the old non-tilting ones but watch where they are set up.
jud
I'm with Newton, not so sure about adjusting a distance due to slope, which is likely a very short sight. The bubble on the rod/tribrach is equally suspect. Maybe that's where the ever mystical 0.04' can be found??
But it does bring up another advantage of being robotic. The robot and the prism are always on the same page. Just like my favorite sport of hockey.... he shoots...he scores...;-)
Depends on how far you have to tilt it to get the shot! LOL....
The result should always a greater distance because of the deflection angle.
There is a pamphlet or website on this that was posted in the past and I am unable to find.
I never worry about it because my use of a non-tilting prism is limited to extremely long shots to a wall of glass (triple prisms clustered together) and am not on 1st order projects.
It is easy enough to use a tilting prism for that shot.
You may have more problems with Vertical Angle Accuracy than Distance Accuracy to non-tilting prisms on steep sights. Take a look at the Eclipse Nodal Point Prisms from SECO {www.surveying.com} for more details on how these prism can reduce sighting errors. RHM