I am looking for a (hopefully affordable) small or mini prism for my Leica TCS 1100 that will utilize the same 0mm offset in my TDS Ranger settings that I use with my current 360° GRZ4.
This will be for shots closer to the ground to help eliminate the 4~6 feet rod height errors, you know for anchor bolts etc. rather than the typical topo shots.
Geodimeter used to (20 years ago) use an excellent prism assembly that you could remove from the top of the rod and just slide it up//down the lower portions of the rod. Boy, that sure was nice.
The GRZ4 is a beast, and I don't like carrying it around unless I have to. I do almost all of my work with a GMP101, which is Leica's tilting mini. It's not a 360°, so I have to be mindful of where it's pointed. It uses a different offset than the GRZ4, so it fails one of Brad's criteria.
However, if you're going to the trouble of ditching the tall pole in search of accuracy, the GMP101 is a good bet. Last year I did 30-some short-range (under 200 feet) monument tieouts with a TCRA1102plus and a GMP101 on a stubby point (HR around 0.4 foot). I tied everything from 2 different points at each site, and rarely missed a check by more than 0.005 foot.
If you need a 360° prism, the Leica GRZ101 looks pretty sweet, but it's pricey. I've never used one.
A couple of years ago I reworked an old Geodimeter 360° to sit at the same height as the Leica prisms so I could use it on relatively short-range (within a few hundred feet) topo without having to pay as much attention to pointing, but I find that I rarely use it. The smallish prisms don't track as well as the larger GMP101, and I was losing lock enough that it wasn't all that much better than the GMP101.
> I am looking for a (hopefully affordable) small or mini prism for my Leica TCS 1100 that will utilize the same 0mm offset in my TDS Ranger settings that I use with my current 360° GRZ4.
>
> This will be for shots closer to the ground to help eliminate the 4~6 feet rod height errors, you know for anchor bolts etc. rather than the typical topo shots.
>
> Geodimeter used to (20 years ago) use an excellent prism assembly that you could remove from the top of the rod and just slide it up//down the lower portions of the rod. Boy, that sure was nice.
You might want to check you offset. The GRZ4 has an 23.1mm offset in Leica land which is about -11.3mm for the world.
That being said the GRZ101 mini 360 has a Leica offset of 30.0mm. Leica also makes 20cm rod that works great for minimizing rod plumb error.
John
The GRZ101 is what I use. About the size of a spool of thread. I keep it in a small pill bottle. I have 4 poles that screw into each other with the slide up/down level bubble. I bought the adapter GAD103 that snaps onto a regular rod and have never used it. The pole/level is all you need. Best layout setup I have had.
Thanks guys, a lot.
I know what I said about prism offsets/constants, maybe I should take that back, just an initial thought.
I also appreciate the comment about my offset settings, but I have tested them and they work...
At any rate I wonder what anyone thinks about this one:
http://www.ebay.com/itm/NEW-MINI-PRISM-W-4-POLES-FOR-LEICA-TOTAL-STATION-17-5mm-/171070799864
Just be aware the one from your link appears to be a low price copy, "for Leica", not Leica.
That prism /pole sold by the manufacturer comes with a sturdier black bag. Works good.
> Just be aware the one from your link appears to be a low price copy, "for Leica", not Leica.
>
> That prism /pole sold by the manufacturer comes with a sturdier black bag. Works good.
Excellent tip. Exactly the sort of advice I was looking for.
Do "they" make some sort of tiny bi-pod for these small rod setups?
Don't know (mini tripod)
A couple of things:
The small tip is easy to loose and cost $20-30 to replace. When changing extension, a guy can get into the habit to temporary screw the tip on the opposite thread so it is not misplaced or dropped in the mud/snow. Also, if not handled with care, extensions can be bent. On the plus side, the prism height determination (a very common source of error in our field) is simple if you don't mind metric. Increments are: 0.1m, 0.4m, 0.7m, 1.0m, 1.3m.
A good prism kit, not the best if you have crews with lack of focus and poor-to-medium equipment care practices.