It was windy today and I had a prism pole in tripod blow over. It probably happens every few years or so. While the prism was undamaged, the target plate got broken so I had to do a little internet search for a replacement. It looks as if the Sokkia Model No. 726648 is still the most bang for the buck, an excellent translucent target, a good tilting mechanism that doesn't flop around, and all for a little over $150 - an unbeatable deal.
I ordered two just to have a spare and will have to probably order a couple of target plates as well. The only thing that prism is lacking is a pointing device to aid in aiming at the instrument. The earlier generation of Sokkia tilting prisms had them and now they don't.
Kent,
I feel your pain. We had a tripod with a prism pole slide through the middle blow over Thursday on an asphalt parking lot. We were lucky that nothing was broken, thankfully.
I do miss the "peep sight" that the older Sokkia prisms had on them.
I hate it when equipment is damaged.
Glad you found a replacement to your satisfaction.
Jimmy
> I do miss the "peep sight" that the older Sokkia prisms had on them.
Yeah, the sight or collimator that the earlier prisms had on them didn't seem like it would cost more than a few bucks to make. It's a shame that option got stripped out because I'll bet I cumulatively spend more than $100 worth of time per year jacking around with getting the prisms aligned without it.
I agree. There is nothing more frustrating than doing your best to properly align the prisms towards the instrument setup, and finding that it needs to be adjusted slightly when you get back to the instrument, especially when you are solo.
For just a few dollars more they sell this tilting prism claiming it is aerospace quality and made here in the U.S.A.
The prism height above the base is an even 100mm, for ease of calculation.
SI ALL NEW 2008 Falcon™ SERIES ALL
METAL PREMIUM 62mm PRISM ASSEMBLY
>
To me, that looks like a poor target design and I have to wonder "what were they thinking?" The yellow green is a high-visibility color,which is good. The target, though, doesn't look as if the person who designed it had ever actually surveyed in daylight.
Leica style prisms have a slot on top down which you site to the instrument to align it.
That works pretty well.
> Leica style prisms have a slot on top down which you sight to the instrument to align it.
Yes, I wish that Sokkia would just add something as an alignment aid.
Kent,
Couldn't you make something to clip on the top, like a cheap rifle sight?
Dave
> It was windy today and I had a prism pole in tripod blow over. It probably happens every few years or so. While the prism was undamaged, the target plate got broken so I had to do a little internet search for a replacement. It looks as if the Sokkia Model No. 726648 is still the most bang for the buck, an excellent translucent target, a good tilting mechanism that doesn't flop around, and all for a little over $150 - an unbeatable deal.
>
> I ordered two just to have a spare and will have to probably order a couple of target plates as well. The only thing that prism is lacking is a pointing device to aid in aiming at the instrument. The earlier generation of Sokkia tilting prisms had them and now they don't.
Kent,
I'm sure that you did a diligent search for the prism assembly that best fit your needs, but is it possible the SECO 62 mm Nodal Point Prism Assembly 6400-10 slipped past your radar? It is one of the few I've seen that has a pointing aid, albeit not the best I've ever used. It also has three possible offsets, 0mm, -30mm, and -40mm.
I've been using a pair of the Seco prism assemblies for about 2 years now and have been pretty satisfied with the results.
It's possible, I suppose, to re-color the target to a more user friendly scheme.
> Couldn't you make something to clip on the top, like a cheap rifle sight?
That's an interesting idea, just buy a cheap collimator/sight and make a bracket for it that will slip over the target plate with the line of sight normal to the target. I'd rather have something permanently affixed to the prism, but that would be an alternative, if something more to carry around in a pocket.
> It's possible, I suppose, to re-color the target to a more user friendly scheme.
Yes, that orange and white target would have to be redone. I'd probably use the vinyl applique film that sign shops use, but by the time I added in the cost of my time that would be one expensive prism.
I haven't been impressed by the quality of other SECO prisms I've bought in the past. In particular, the tilting prisms have been very floppy. I have a couple of brand new SECO prisms (non-tilting) that I used for a couple of days and just set on the shelf. The prism canisters were held in place by a very cheesy knurled screw that wasn't up to the task of actually holding the prism tight and square in the mount.
> I haven't been impressed by the quality of other SECO prisms I've bought in the past. In particular, the tilting prisms have been very floppy. I have a couple of brand new SECO prisms (non-tilting) that I used for a couple of days and just set on the shelf. The prism canisters were held in place by a very cheesy knurled screw that wasn't up to the task of actually holding the prism tight and square in the mount.
It's true what you convey; early models of the SECO tilting prism assembly were inferior in many ways. However, this particular model that I refer to doesn't seem to suffer from those issues. The friction lock has held up well in the two years that I've used them. The prism canister actually screws into the mount and seats rather well.
All that doesn't mean that tomorrow the things won't fall apart, but to this point I've had plenty of confidence in the prism assemblies.
> However, this particular model that I refer to doesn't seem to suffer from those issues. The friction lock has held up well in the two years that I've used them. The prism canister actually screws into the mount and seats rather well.
>
> All that doesn't mean that tomorrow the things won't fall apart, but to this point I've had plenty of confidence in the prism assemblies.
Well, with your good experience with them, I'll keep those SECO tilting prisms in mind, particularly if they ever change the target design to yellow-green triangles on black background.
Kent - This is what your setup was thinking....
And I bet this is how you felt
Sorry Buddy!
You have my sympathy along with others...
Wishing you the best of luck in your search and endeavors. 🙂