We have used our SX10 almost exclusively for scanning up to now. Last week I setup control for scanning some bridge approaches on an interstate using GPS. I set an intervisible pair at each bridge, one point on each side of the bridge. One of the bridges is over a large river, and I set one point on either side of the river. Distance between them is 1009 meters. Crew says today it will not shoot between them (need to get a backsight to do the scans). Spec sheet says autolock to 800 m, so that is why it will not autolock. But, it also says it will shoot 5500 m to a single prism. He says you cannot see the prism/tripod on the data collector screen (which is required since there is no way to look through the instrument for aiming other than using the camera and DC screen. Workaround is to set another point using GPS that is closer, but not so easy because the highway descends through a steep sided cut to get to the bridge.?ÿ
Anyone have any experience using the SX10 to get a LONG backsight? Of course the distance to the backsight is not necessary (but preferred), but he says you cannot even see the tripod much less the prism. I reckon a strobe might work. Also, I am not sure how accurately the instrument can be pointed using the on screen controls.?ÿ
We have a dam deformation that we do every 2 months using an S6 that has a 1800 m sight, but it is always done manually, you can see the tripod and just point to the top of the tripod where the prism is. We only need a distance in that case, angle does not matter.?ÿ?ÿ
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I've never tried sighting quite that far, if I had to guess I'd say 600 - 650 meters is about the farthest, but at that distance is was remarkable how well I could zoom in on the object I was looking at (typically a transmission wire where it tied to the insulator on a transmission tower). Could the problem be related to heat shimmer and / or humidity? At the highest zoom level a tripod should be very easy to identify at that distance. Granted, a transmission line hanging from a tower is well silhouetted against the sky and thus easy to pick out. But even at that distance, you have to find it at a much lower zoom level and then zoom in incrementally. If you jump straight to the maximum zoom level you'll have trouble finding something as small as a prism.
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I question that 800m autolock spec... maybe at 6:00am on a cool morning in a desert at high altitude... not in Louisiana. The position of the prism with respect to the sun seems to affect this a great deal.
The sight was being blocked a lot by truck traffic I was told. One end was low and the other end was on the grade going up from the bridge, about 10 m difference in elevation. So it was not skimming the surface of the bridge.
Like I always say...works great in the lab...