Bubble Trubble

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  1. Re: Bubble Trubble

    #16
    Users Country Flag
    Join Date: Apr 2008
    Location: Saddleworth UK
    Posts: 242

    Nick

    you are 100% right.... but this is something that will continue to haunt every one who fits bubble levels.
    If you went to the trouble of offering an adjustable bubble, people would not want to pay the price, and even fewer would use it.

    If they actually understood how their software functioned they would not worry at all about bubbles.
  2. Re: Bubble Trubble

    #17
    bigwade's Avatar
    Join Date: Apr 2008
    Location: Utrecht, The Netherlands
    Posts: 67

    Hi Folks,
    I'm a kind of level/bubble freak... :-)
    I like to collect all kind of those tiny acryl bubbles.

    After reading this topic, I could not resist :-)
    In our kitchen we have a glass induction plate for cooking.
    Guess what ? It is in Level !!

    So I put all the NN's I have on the same place at the plate without a camera.
    NN3/NN5/NN180/NN R1/R10
    The R 10 has an original ext. NN bubble, the ring bubble.
    The R1 it's own + an original ext. NN bubble.
    I rotated all NN's in 4 steps about 90 degr.
    At ALL NN's, the bubble stayed in the black ring EVERY 90 degr.
    The R1 AND R10 are the absolute winners, followed by NN180 and NN3.
    The NN5 was at "last" position, bad ? NOT AT ALL !! it was just a tiny, tiny difference.
    So Nick Don't worry ! It's not the rig ! All are more or less spot on.
    No need for an adjustable bubble.

    Now what can cause a running bubble if it's not the NN ?
    A) a not so sturdy floor like carpet, grass or sand.
    B) a not so sturdy centre-column of the tripod
    C) both !

    About "A" that's clear I guess.
    With a camera hanging out of balance on a NN3/5 one leg of the tripod has more force to handle.
    About "B" With a camera hanging out of balance on a NN3/5 the force on the column is huge and with a not so well guided column you get flex and hey.........the running bubble.
    Fanotec can make a BATCH HEAD but without a sturdy, well guided centre column-tripod it is not going to work.
    Good tripods I know, Gitzo/Feisol
    Problem solved.

    Last point;
    I tried a NN3 with 5D2 on a carbon monopod mounted upside down on a Heavy but small Gitzo.
    After 1 rotation (90degr) I had to wait before it was not moving again.
    Tried the same with the R1 and that was much more balanced because the camera is centered ±ON the rotation point and it will only hang backwards a bit.
    It's all a matter of weight and place of the weight, direct on top or forces via L-bow

    grtz
    Frank
  3. Re: Bubble Trubble

    #18
    bigwade's Avatar
    Join Date: Apr 2008
    Location: Utrecht, The Netherlands
    Posts: 67

    Ah, forgot one thing..
    D) the flex of the rotator...... :-)

    The R-D4/8 etc series are much better than the standard NN3/NN5 rotators, fact.

  4. Re: Bubble Trubble

    #19

    If Bigwade's theory were right I could never find a "right" position for the bubble, but this is not the case: I have found the right mark on the bubble which is close to the black circle and when the bubble is located there, it will stay there during the a full (slow) rotation. I have a good tripod but nothing exotic. Obviously rigidity is not an issue in my case at least.

    But I'm happy now and I agree with Nick, making an adjustable bubble will create more problems than it solves.

    As for the other friend who wrote that we would not bother this bubble issue if we understood how the software works I choose the Gandhi way: peace and love to you!
  5. Re: Bubble Trubble

    #20

    Hello Mike,

    As Terry pointed out a moving bubble isn't an issue when you know how to use your stitcher,
    As Nick pointed out the precision of the bubble level of NodalNinja products is pretty good,
    As Frank pointed out there are more reasons why a bubble can move,
    As I pointed out if a bubble movement really bothers you then you can find the real center of the bubble level to make it precise.

    IMO all is true ;-)

    In this thread is not mentioned yet when a precise bubble level is needed and when not.

    * When stitching panos without setting horizontal or vertical CP's, or other ways of leveling in the software, then a precise bubble level is needed to get a fine leveled horizon.

    First some math to get an idea about the impact of an error of a bubble level off set.
    A bubble level off set of 0.5 degree will cause a variation of 2*0.5=1 degree over 180 degree (=half the width of a pano).
    The impact of this on the horzion of a pano of 7200x3600 px will be a slope of 3600/180<>20px at the horizon.
    When the view angle of the pano player is 75 degree then the slope of the horizon in the players window will be 75/360*20<>4 px.
    IMO a slope of 4 px of the horizon is hardly noticable and so acceptable.

    For larger panos the slope can be larger but in practice this is hardly the case.
    See for example this 9600x4800 px pano that is shot at the shores of a large lake with a carefully leveled R1, despite the fact that there are no horizontal CP's set, you will hardly see any sloping of the horizon:
    http://www.dmmdh.nl/panos/ouddorp_ha...image_002.html

    * In all other situations, so when the pano is leveled with the software, the precision of the bubble level, or the lack of precision, is not of any impact on the quality of the pano as long as the proper level is manually set in the software.
    See for example this 8400x4200 px handheld pole pano:
    http://www.dmmdh.nl/panos/pole_pano_...image_014.html

    Conclusion: both examples proves that you don't need a "perfect" bubble level with zero tolerance to get a good leveled pano.

    BTW, I can confirm the results of Frank's tests, the bubble levels of the NN products he mentioned are all within the precision needed for batch stitching(!).
    (!) With all mentioned NN products you can get good results with a EasyStitch method. This method is based on a calibrated lens template, no horizontal or vertikal CP's are placed and only the lens shift and image params are optimized in an automated batch stitch process.

    I hope this helps to take away any confusion or misunderstanding.

    Wim
  6. Re: Bubble Trubble

    #21
    bigwade's Avatar
    Join Date: Apr 2008
    Location: Utrecht, The Netherlands
    Posts: 67

    Quote Originally Posted by realman10 View Post
    If Bigwade's theory were right I could never find a "right" position for the bubble, but this is not the case: I have found the right mark on the bubble which is close to the black circle and when the bubble is located there, it will stay there during the a full (slow) rotation. I have a good tripod but nothing exotic. Obviously rigidity is not an issue in my case at least.
    Ok?©, if you have a sturdy tripod on a sturdy floor, rotating, the bubble is at the same place you are correct.
    If you have problems with that ask Bill or your local reseller to replace your underrail.
    BTW it's not theory but just what I see with a good and not so good tripod.
    Even with the "not so good tripod" or monopod on a tripod with all the bubble-walking I see, I get perfect final results.
    grtz
    Frank
  7. Re: Bubble Trubble

    #22

    Slightly OT: Wim I also use something similar to your EasyStitching, but the shift correction is part of my lens calibration data (which I freeze for one specific focusing distance, 1m @f/10 basically the hyper-focal distance). Normally I don't optimize the shift parameter for each project.
    I mostly use a D3 with a rectilinear 14mm Sigma which has excellent resolution and geometric stability (but is weak on flare and vignetting).
    I just load the images, load the template and the panorama is 99% ready BEFORE any optimization and CP work. Since I received my NN5 things have improved further and now every project is a breeze. I even did a high resolution job with a 50mm lens and again it was a piece of cake...Thank you Ninja...and Nick!
  8. Re: Bubble Trubble

    #23

    Hello Mike,

    In my EasyStitch method I also optimize for the lens shift params because on my cameras (Canon) there is a very little movement possible of the lenses in the bajonet mounts.
    Although not much, approx. 0.2mm in all directions, this small movement can cause a shift of the projection of the image on the sensor of approx. 30 px (depending on the size and resolution of the sensor it can be more or less).
    When it occurs and the template is not optimzied for lens shift the small movement will cause visible errors.

    Wim
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