Aloha, I was attempting to do collimation adjustment on my TS but I am having difficulties with this exercise. Wondering if anyone here can share their knowledge and wisdom?
Here are few things I understand and got to so far. Please correct me if I am wrong.
1. For HA and VA collimation I need to have a minimum of 328 ft (100M) between the gun and the target. I have two points that are 600 ft apart. So I am okay with this requirement…No problem so far.
2. I have to aim toward a point near the horizon at max. 5 degrees to the horizontal. Need verification on this one...
Does this means I have to have the setup on a flat area? I should not be pointing to a target on a hill or slope that will cause vertical angle reading more 5 degrees. Correct?
3. Finally, for the Trunnion collimation—I supposed to change 13.5 degrees above or below the HA and VA collimation point utilized earlier. While keep the target at a minimum distance of 66 ft. (30M). This is the challenging part…I could not get this to work. When I maintain the distance, I cannot obtain the angle required. When I set the gun to the required angle…now I have to have the target about 20 ft. or so away from the gun. Any tricks to make this to work?
Thank you so much!
2. Yes, you want to be on a fairly flat spot.
3. I think that you are doing it right, it just wants you to be really, really fine with your sightings. I used to do this to the head of a streetlight across the street from our office, but if it was the slightest bit windy the streetlight would move too much. The vertical of the sighting is as critical as the horizontal.
Don't be too hung up about the distance limitations on these tests. These are really guidelines rather than hard and fast requirements.
> 2. Yes, you want to be on a fairly flat spot.
>
> 3. I think that you are doing it right, it just wants you to be really, really fine with your sightings. I used to do this to the head of a streetlight across the street from our office, but if it was the slightest bit windy the streetlight would move too much. The vertical of the sighting is as critical as the horizontal.
>
> Don't be too hung up about the distance limitations on these tests. These are really guidelines rather than hard and fast requirements.
:good:
I agree 100%. You want a target that is solid and easy to fine-tune on and doesn't move. A natural site on top of a building or anything else is great as long as you can re-find the exact same spot (with confidence). If it's closer than 30 meters, I often find a scratch-mark or make a fine pencil-mark or something on my target that I know I can aim at precisely. A big-ole range pole or target 1000' away dancing in the heat waves might be worse than a pencil-mark on a surface 30 feet away.
> 2. Yes, you want to be on a fairly flat spot.
>
> 3. I think that you are doing it right, it just wants you to be really, really fine with your sightings. I used to do this to the head of a streetlight across the street from our office, but if it was the slightest bit windy the streetlight would move too much. The vertical of the sighting is as critical as the horizontal.
>
> Don't be too hung up about the distance limitations on these tests. These are really guidelines rather than hard and fast requirements.
Aloha, Mark:
Thanks!
Can you stay within the 5º from horizon when you sight the streetlight? I guess you can if the streetlight is pretty far.
Yeah, I was a bit concern when I only able to achieve maximum of 20 plus feet. We try again.
Thanks you again!
>
> :good:
>
> I agree 100%. You want a target that is solid and easy to fine-tune on and doesn't move. A natural site on top of a building or anything else is great as long as you can re-find the exact same spot (with confidence). If it's closer than 30 meters, I often find a scratch-mark or make a fine pencil-mark or something on my target that I know I can aim at precisely. A big-ole range pole or target 1000' away dancing in the heat waves might be worse than a pencil-mark on a surface 30 feet away.
Aloha, Tom:
I did this late afternoon in a fairly shady palm grove. I wasn't thinking about heat waves B-)...but trying to avoid our Hawaiian hot sun 😀 I setup a prism at 600 ft. As Mark point out...I got hung up on the trunnion collimation when I ended up less than 30 meters. Now I understand it is okay if I can maintain the minimum distance.
Thank you so much for additional guidance!
> Can you stay within the 5º from horizon when you sight the streetlight? I guess you can if the streetlight is pretty far.
To be clear, I used the streetlight for the trunnion axis adjustment only. For the other two tests I used a tripod mounted target. For the autolock test/adjustment, you need an active target diode, of course.
Aloha, Mark:
Phew! Thank you for the clarification!
This leads to another question...So I don't have to keep the scope aligned to the same point that I did the HA and VA collimation when I do the adjustment for the trunnion? I was keeping the gun in the same horizontal angle!!
Thanks!
Each of the 3 tests are independent. You could use 3 completely separate targets. In fact, you must use at least 2 (one on the flat, one at a high vertical angle) to complete the 3 tests.
Thanks Mark. I got it! Aloha
I think your idea of 100 meters actually relates to a "peg" test of a level. For H & V col of a TS I find that I can do these in my basement with sites of about 20'. Further, instrument shops are looking at targets that are about 2' away. Granted the collimation machines that the use give the appearance of looking at infinity, but they are still about 2' away. You could actually use another instrument the way they do by looking through the objective lens with both instruments focused at infinity.
I like doing this in my basement (or any where indoors) because of the climate control.
As to vertical collimation, you will want to read the manual for your instrument. While you will want the cross hairs pretty close, many TS's will do the vertical collimation electronically.
I suspect that most TS's are not of sufficient accuracy to worry about the trunion axis and you will most likely not be taking very high vertical, astro shots where this is critical. It's nice to check it to make sure it's not way out, but I doubt you'll find it very far out - if any measurable amount. This is where it would be good to use another instrument as your target.
To use another instrument as a target you need to back light the cross hairs. This can either be done with an auto-collimating eyepiece or a diffused light through the eyepiee. This will be very handy for the 30 degree or greater sight for the trunion axis test.
Feel free to ask additional questions.
PS I have used these methods to adjust everything from transits through theodolites to T3's & T4's to TS. It works fine.
PPS One thing you didn't mentions is to get your plate levels as close as possible before doing anything else.
> I think your idea of 100 meters actually relates to a "peg" test of a level. For H & V col of a TS I find that I can do these in my basement with sites of about 20'. Further, instrument shops are looking at targets that are about 2' away. Granted the collimation machines that the use give the appearance of looking at infinity, but they are still about 2' away. You could actually use another instrument the way they do by looking through the objective lens with both instruments focused at infinity.
>
> I like doing this in my basement (or any where indoors) because of the climate control.
>
> As to vertical collimation, you will want to read the manual for your instrument. While you will want the cross hairs pretty close, many TS's will do the vertical collimation electronically.
>
> I suspect that most TS's are not of sufficient accuracy to worry about the trunion axis and you will most likely not be taking very high vertical, astro shots where this is critical. It's nice to check it to make sure it's not way out, but I doubt you'll find it very far out - if any measurable amount. This is where it would be good to use another instrument as your target.
>
> To use another instrument as a target you need to back light the cross hairs. This can either be done with an auto-collimating eyepiece or a diffused light through the eyepiee. This will be very handy for the 30 degree or greater sight for the trunion axis test.
>
> Feel free to ask additional questions.
>
> PS I have used these methods to adjust everything from transits through theodolites to T3's & T4's to TS. It works fine.
>
> PPS One thing you didn't mentions is to get your plate levels as close as possible before doing anything else.
Aloha, Dave:
Thank you for the additional thoughts.
I got all the procedures of the TS manual. But I couldn't decipher it due lack of exposure and knowledge.
I have to learn more about peg test... haven't done that yet 🙁 I glance through them as I was studying Survey books.
Unfortunately, I only have one total station. I don't own any other instrument such as transit either. So I am stuck with prisms.
My TS does the collimation adjustment electronically. I was just a bit lost with the procedure until Mark (Norman OK) and Tom enlightened me!
You are absolutely correct, I don't think I'll ever use astro shots or high verticals--at least not at this time. Although sometime in the future I may monitor our temple tower just for the fun of it. But that is only 40ft tall.
"Plate level" this the tripod head right? Yes, I am always very meticulous when come to setup. I always take my time to get them level with tribrach bubble. Then with the electric level bubble in the DC.
Thank you again for sharing! Everyday I learn so much from each one of you!
> I have to learn more about peg test... haven't done that yet 🙁 I glance through them as I was studying Survey books.
Peg tests are specifically for differential levels. I'm not sure that you have one of those.
To meet Trimble's distance/angle requirements, I could find only 1 location in my town that was high enough (radio station tower).
I can only do the collimation routine on a calm morning. I do get repeatable results.
The main intent of sighting something so high is to establish the tilt axis error.
You should see the corrections being applied if you zero you gun looking at a zenith of 90° and slowly adjust the vertical axis. The horizontal angle should stray from zero.
> Peg tests are specifically for differential levels. I'm not sure that you have one of those.
Aloha, Mark:
I just looked it up. I am definitely not doing peg tests.
Thank you
> To meet Trimble's distance/angle requirements, I could find only 1 location in my town that was high enough (radio station tower).
>
> I can only do the collimation routine on a calm morning. I do get repeatable results.
>
> The main intent of sighting something so high is to establish the tilt axis error.
>
> You should see the corrections being applied if you zero you gun looking at a zenith of 90° and slowly adjust the vertical axis. The horizontal angle should stray from zero.
Aloha, Imaudigger:
So I am not alone on this...it was driving nuts! I am very relief after getting all the guidance after posting here. I spent two afternoons on this and wasn't going anywhere. Now I have a very clear understanding of the routine.
Thanks for the input.
Not sure if you are using the ACU w/Survey Controller software, but I put this together years ago as a cheat sheet. The back side had a map indicating where to set the back sight and the instrument.
> Not sure if you are using the ACU w/Survey Controller software, but I put this together years ago as a cheat sheet. The back side had a map indicating where to set the back sight and the instrument.
Aloha, Imaudigger:
I don't have Survey Controller. But your cheat sheet still very informative.
Thank you so much!
