Okay so popping my cherry on my Topcon here, and first of course verifying my prism constant setting. After being massively confused for 2 hours yesterday afternoon, I realized the NP (reflectorless) distance was giving me a 0.13' shorter distance than it should. The instrument has no constant applied, so it does not make sense.
Even more confusing, if I just shoot anything NP "long" and never move the gun - just shoot back and forth between NP long and NP standard, I get this difference. NP long gives me the correct distance, and NP standard is off. I do not see the gun change to some weird prism constant or PPM setting when I do this.
(I am shooting a fencepost or the top of the hub that I set the tribrach/tripod over)
Anyone have this issue? I am using a Topcon GPT 9003A
Out of curiosity, what type of gun did you previously use?
> Out of curiosity, what type of gun did you previously use?
Leica TCRA 1103+
Yesterday morning the EDM fried out on me.
I will make a prediction that you will never like the topcon.
But that said, this is a guess: Long mode is for long distances and probably does some funny things to the beam convergence when shooting a target at close range. I just Googled Topcon no prism long and found a brochure for a 9 series robot. The long mode NP has an accuracy of +/- 100mm in some applications!?!?!?
> I will make a prediction that you will never like the topcon.
I expect like most things I will like and hate certain things. I have no idea how I can rely on some 1500 shot with the NP long setting, but then again I do not expect to use it for much. It is pretty cool though.
As for the brand, I have to go with the support at this point. Chuck Madrid is very responsive.
The motor on the new gun is much nicer. I will see how I feel about the robot very soon.
I cannot speak for Chuck's method of setting instruments up for field use but I am certain his people know what they are doing, and I know what we do. There should be a prism constant for prism mode applications if you are using the standard A7R 360° prism but by definition, there should be a 0 prism constant for any non-prism mode.
Depending on the style of 360° prism you are using, the prism offset could be -2 mm for the A7R prism or it could be 0 mm for the A6R.
When going through the instrument settings for prism offsets, it will give the correct offsets for the style of prism if you look it up on the pop-out menu.
When using an instrument in reflectorless laser or “No Prism” mode, there is no “prism constant” involved since the instrument is measuring directly to the surface. The problem arises when the operator forgets to switch back to IR mode when sighting a prism. Since the prism constant is that leg of the triangle where the light beam is being reflected inside the prism your measurements will be off by the “prism constant” amount the prism being used has. When I forget to switch the EDM mode to IR from Laser in my Leica TCRP 1203 I’m off about 0.08’ since the prism constant for my 360^ prism is 23.1 mm; it would be off 0.11’ for the “round” Leica glass which has an actual prism constant of 34.4 mm (which is 0 in Leica’s world).
The NP in "regular mode" measures .14' shorter on the same object shot in NP "long" mode. It is something to do with the standard NP mode. There is nothing set in the gun that would make it change the distance measured between those two modes. I think there is something else set that I cannot figure out.
I also shot the top of the hub, not the glass, when checking this in relation to my infrared shots adjusted properly to the prism constant. I also went out today to an area that I had adjusted in StarNet which was shot with the Leica, and three points checked under .01' with the infrared mode, so I know I am getting good distances with the gun. It is something weird with the NP mode.
I can easily apply a fake prism constant on my data collector but would prefer not to do this and find out why it does this.
Sorry to hear of the passing of your 1103.
I am sure it was a good worker for you since I have the same gun.
I had my edm replaced 5 years ago when they were still working on these.
Maybe I will get a few more years out of it.
Randy
>
> I had my edm replaced 5 years ago when they were still working on these.
>
Well that makes me nervous.
I am supposed to hear back from someone on the cost for fixing it. We will see.
Yes I was quite fond of that little guy. It worked well.
Maybe someone still works on them, but I was told otherwise by Leica.
I think it cost $2500 5 years ago, fortunately my insurance picked up the tab.
You can almost buy a used 1103 for the cost of fixing one these days.
I will give that thought heavy consideration if mine takes a dump in the near future, but right now it works like its supposed to, nice, tight and sweet.
Good Luck.
Randy
> I think it cost $2500 5 years ago
*UPCHUCKS*
I guess I should not be surprised.
How is it your insurance covered most? Was there some accident involved, or is repairing something like that somehow a part of your policy?