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  1. Bubble Trubble

    #1

    If I adjust my NN180 so that the bubble is dead centre in the reference circle of the spirit level, why does the bubble shift as I rotate my camera?
  2. Re: Bubble Trubble

    #2
    Users Country Flag badders's Avatar
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    Because it does... Use it as a reference only for initial setup. As you're only shooting 1 x row of images with the NN180 it doesn't matter if the image isn't aligned to the horizon at time of shooting because you can fix this in your stitching software.



    Badders
  3. Re: Bubble Trubble

    #3
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    Quote Originally Posted by newboy View Post
    If I adjust my NN180 so that the bubble is dead centre in the reference circle of the spirit level, why does the bubble shift as I rotate my camera?
    the bubble is very sensitive. when you rotate the camera, there can be very slight movement of tripod. This will cause the bubble to move. Also, the level is set accurate only to certain extent. There is no perfect level in this world.
    The bubble is fine if it does not move out of the black circle. It will not affect your stitching.


    Nick



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  4. Re: Bubble Trubble

    #4
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    As Nick says the bubble is very sensitive.
    when you set up, you area aligning the plane of rotation...(The flat surface in the rotator) to be level.
    After that you must leave it alone. or you may give problems to your stitcher.

    As you rotate the arm and camera, the weight distributed through the three legs of your tripod changes, even a minimum amount of flex is noticed by the sensitive bubble.
    There is likely to be some minimally measurable flex in all tripod systems, ball heads, levellers and camera mounts.
    However you will notice as you continue the rotation to where you started, the bubble will be level again. this shows the plane of rotation is constant even if the bubble moves.
  5. Re: Bubble Trubble

    #5

    Quote Originally Posted by nick fan View Post
    the bubble is very sensitive. when you rotate the camera, there can be very slight movement of tripod. This will cause the bubble to move. Also, the level is set accurate only to certain extent. There is no perfect level in this world.
    The bubble is fine if it does not move out of the black circle. It will not affect your stitching.


    Nick
    So you wouldn't suggest I re-level at 180 degs?
  6. Re: Bubble Trubble

    #6
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    Quote Originally Posted by newboy View Post
    So you wouldn't suggest I re-level at 180 degs?
    no. as with any pano head, don't re-level it. Actually, bubble level in all pano heads move to some extent doing rotation. It is never a problem.


    Nick



    Fanotec
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  7. Re: Bubble Trubble

    #7
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    If nick used some of the less accurate bubble levels in his manufacture. bubble movement may then, not even be noticeable.
    However who wants a less accurate product?
  8. Re: Bubble Trubble

    #8

    Quote Originally Posted by Terrywoodenpic View Post
    If nick used some of the less accurate bubble levels in his manufacture. bubble movement may then, not even be noticeable.
    However who wants a less accurate product?
    I'm sorry, but you are missing the point. The accuracy of a bubble level is not in bubble itself but IN THE WAY IT IS MOUNTED.
    And it looks like many NN5, mine included, have a bubble which is not perfectly parallel with the rotation plan of the lower arm.
    I'd like to ask Nick if there is a way to take the bubble off and then re-install it in a proper way.
    My first nodal head was a Panosaurus, clearly inferior to the Ninja, but it had a detachable bubble (which kept falling onto the ground as I forgot to take it out), but at least I had been able to tune it very finely so that by turning the lower arm it would keep the level plane.
    Nick, any advice? it's the only disappointment I had with the NN5.
    Thank you
  9. Re: Bubble Trubble

    #9
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    Quote Originally Posted by realman10 View Post
    I'm sorry, but you are missing the point. The accuracy of a bubble level is not in bubble itself but IN THE WAY IT IS MOUNTED.
    And it looks like many NN5, mine included, have a bubble which is not perfectly parallel with the rotation plan of the lower arm.
    I'd like to ask Nick if there is a way to take the bubble off and then re-install it in a proper way.
    My first nodal head was a Panosaurus, clearly inferior to the Ninja, but it had a detachable bubble (which kept falling onto the ground as I forgot to take it out), but at least I had been able to tune it very finely so that by turning the lower arm it would keep the level plane.
    Nick, any advice? it's the only disappointment I had with the NN5.
    Thank you
    I know exactly what you mean.
    However You may not think so, but the bubble is more accurate than it even needs to be.
    Provided it stays in the ring it will have no effect on the stitch as the plane of rotation will be identical in every shot.
    The "plane" of rotation is always as accurate as the surface of the rotator.
    (Provided that is, you do not adjust the head to level the bubble with each shot.)
  10. Re: Bubble Trubble

    #10
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    Pay attention to the bubble once: in the beginning of your shots. Take your tour around and it will be at the same place. I never had stitching problems with levelling at the beginning.

    To compare the results, i tested a round relevelling in between: i got a lot of stitching problems, had to add lot of controlpoints manually.

    So this was the proof for me to leave it alone as was explaned above.

    When you don't believe it, test it on your own with releveling, and i think you will spend a nice evening.


    Heinz
  11. Re: Bubble Trubble

    #11

    Hi, let me make myself clearer:

    1. I am not saying that you need to re-level the head as you turn it around, that would be totally wrong. Since we know the level is offset, by re-leveling you only make sure that it is always off-level and always in a different off-level state. Not very good right?
    2. The fact that when you complete the 360¬? turn it comes back to the right level proves nothing, just that the head and tripod did not move, the very least we can expect
    3. The problem is not in the bubble but in the incorrect way the bubble is mounted that is not perfectly parallel to the rotating plan of the lower arm.
    4. Everyone obviously chooses his own quality standards.

    I'm getting the uncomfortable feeling that I am being seen as a "provocateur", which I am not. I am a paying customer trying to help improve a good but not perfect product.
    The only real answer I got so far is that this is not a serious issue and we should accept the small error, let's call it tolerance for convenience.
    For those who are interested I've found a workaround: find the real neutral position of the bubble, which would be probably when the bubble is somewhere on the border of the black ring and then mark that position with a tape. Next time just set your rig so that the bubble is again in the marked position. Now if you turn the arm around, the bubble will stay in the same position, in other words it will not move around. Now the head is properly leveled.

    I still believe that a properly calibrated bubble is a pre-requisite for any quality precision tool, no matter how critical the item may be.
  12. Re: Bubble Trubble

    #12

    Hello Forum,

    Many people using all kind of panoheads from different manufacturers are complaining about there bubble level.
    The issue is not that the bubble level itself is inaccurate but that the precision of the leveling when it is mounted (often glued) is not 100% but at most 99.99%
    This very small off set is normal as long as the bubble keeps inside the black circle of the bubble level and can be ignored.
    However even the smallest off set of the ideal level mounting position is causing a moving bubble when the panohead is rotating with complaints as a result.

    An off set is not as bad as it sounds but if you want to have a "precise" bubble level you can "adjust" every bubble level yourself, not by removing the bubble level and then remounting it but by finding the real center of the bubble level and then marking or memorizing this point.
    This is how you do it:
    1) mount your panohead on a sturdy tripod and place the tripod on a hard en solid surface,
    2) level the panohead so that the bubble is in the centre of the black marked circle of the bubble level,
    3) rotate the panohead 180 degree, for sure the bubble will move and perhaps even will go a little outside the black circle !
    4) adjust the legs of the tripod, or use a panohead leveler if mounted, to level the bubble "halfway" the original center position and the new position, remember this "halfway" position, think about the position like it was a clockwork and memorize the "time" of the bubble,
    5) rotate the panohead 90 degree, the bubble will move again,
    6) level the bubble again "halfway" the last (memorized) position and the new position and remember the new "halfway" position,
    7) repeat step 4 to 6 and eventually you will find a point where the bubble is not moving,
    :001_cool: congratulations, you have found the real center of the bubble level and all you now have to do is to memorize this position (again think about it like it was a clockwork) or you put a small dot with a black permanent marker pen in the center of the bubble,
    9) when using the bubble level the next time you don't level the panohead by using the black marker circle but instead you level to the real center of the bubble level and you will see that now the movement of the bubble will be very small or even absent :-)

    Success,
    Wim
  13. Re: Bubble Trubble

    #13
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    Wim.Koornneef's way seems to be ideal for any one who is anal about this.
    However you can make perfect spherical pans with the head in any orientation, It simply is not an issue for stitchers.

    I am sure Nick would say the that neither perfect bubbles nor perfectly set bubbles are economic.
    Scientific and engineering instruments usually come with adjustable bubbles that you can set yourself. Those with fixed bubbles will state the tolerance. ( usually quite large.)

    I would have thought. a bubble with a spherical base could be made, at a reasonable price, that could be self set and locked in place with a top cap. If this were to be true Nick could sell it at a premium price as an alternative.

    However I am very happy with my bubble as it is.

    The bubble on a tripod does not usually rotate, so we are unaware how inaccurate they always are.
  14. Re: Bubble Trubble

    #14

    A big thank-you to the mods.
    Problem solved, I'm also happy I gave a little contribution.
    A prompt response like this glues a customer forever, I know you are mods and not employees but the community is here!

    Mike
  15. Re: Bubble Trubble

    #15
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    Quote Originally Posted by Terrywoodenpic View Post
    Wim.Koornneef's way seems to be ideal for any one who is anal about this.
    However you can make perfect spherical pans with the head in any orientation, It simply is not an issue for stitchers.

    I am sure Nick would say the that neither perfect bubbles nor perfectly set bubbles are economic.
    Scientific and engineering instruments usually come with adjustable bubbles that you can set yourself. Those with fixed bubbles will state the tolerance. ( usually quite large.)

    I would have thought. a bubble with a spherical base could be made, at a reasonable price, that could be self set and locked in place with a top cap. If this were to be true Nick could sell it at a premium price as an alternative.

    However I am very happy with my bubble as it is.

    The bubble on a tripod does not usually rotate, so we are unaware how inaccurate they always are.
    Is there a real need to get perfect level? The fact that other manufacturers are accepting this "problem" allows us to justify this "problem". :-)
    We try to set the level as accurate as possible. We mount the lower rail on a heavy metal block which is leveled using instrumental precision bubble which is calibrated EVERY time before use. The bubble is glued on the lower rail using very thin layer of epoxy. Before the epoxy is cured we set the bubble so that it is centered. We keep checking the bubble till the epoxy is cured. Of course, human is prone to error. and every degree of error will be doubled when the lower rail is rotated by 180 deg. The bubble in NN5 has a sensitivity of 34' (0.57deg) per 2 mm movement. To set a tolerance of 1mm bubble movement, we need 34'/4 (remember 180 deg rotation doubles the movement)=0.14 deg of accuracy which is pretty high for my OWN standard.
    You know what, even the instrument grade bubble will shift every time before use. Recalibration is needed. I guess it has something to do with thermal expansion. But then instrument grade bubble is much more sensitive.

    We can make the bubble adjustable, say by making a bubble holder which is mounted to the lower rail by 3 screws. By adjusting these 3 screws, the level can be adjusted. Then I know 99.7% users will not use this feature and 99% users will have problem in calibrating the bubble. I am not sure how many people will justify the added cost. and not to speak the danger of failing to restore acceptable leveling after attempt of calibration. I can almost hear their complaint. "Damn, stupid Nick! Why not set and glued the bubble as other manufacturers do."

    Nick





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