NN4 with RD16, Canon t2i (550D), and sigma 8mm fisheye.

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  1. NN4 with RD16, Canon t2i (550D), and sigma 8mm fisheye.

    #1
    Question

    Hi!

    Does anyone happen to have the NPP value's for the t2i (550D) with the 8mm sigma fisheye?

    Also, do I need to use a t-adapter with this camera... it seems like the camera tripod mount may be offset from the centre of the barrel of the lens. Please correct me if i'm wrong but i'm just starting out and wondering if that's the issue.

    Im using nodal ninja 4 with rd16.

    Thanks in advance!'
  2. #2

    Hello PanoArchitect,

    Align the gold ring of the Sigma 8mm with the vertical access of rotation of your Nodal Ninja 4.

    See:
    http://hugha.co.uk/NodalPoint/Index.htm#Sigma%208mm

    Viewing the lens from the front, align the centre of the lens with the vertical axis of rotation of your Nodal Ninja 4. If you set up the camera on a tripod with the light behind the viewfinder you will see the centre of the lens as a bright spot and be able to use a vertical line (e.g. a door jamb) to lign up the lens centre with the mark on the NN.

    This should give you the required location.

    I believe that the 1/4" tripod screw for the 550D is in line with the lens axis so you should not need a T adaptor (unless someone else knows different).

    Best regards, Hugh.
  3. #3

    This page from DPReview.com shows that the tripod mount of the 550D is in line with the lens axis.
    .
    http://www.dpreview.com/reviews/canoneos550d/5
    .
    The upper rail setting on the NN4 is probably around 87mm when taking four shots around. A little less if you use 6 shots around. 4 shots around gives you 15% overlap, which is usually sufficient. 6 shots gives 44%, which might be useful on occasion. Hugh's suggestion of using the visible entrance pupil to set the lower rail position is a good one. You can also use it to find the correct upper rail setting. It takes only a few minutes, so it's well worth learning how to do it. See http://www.johnhpanos.com/epcalib.htm for full details.
    .
    John
  4. #4

    Thanks for the links guys... I think we've concluded that the tripod mount is in fact in line with the lens axis.

    I used the above method Hugh recommended (and also from the johnhpanos link) to find the centre of the lens and line it up with the axis and then also adjusted the lower and higher rails accordingly and it seemed to be working fine. However, when I went back to check the original lower rail with a different method (using a needle and cardboard) I ended up getting a different number (49mm first and then 51mm) which also changed the upper rail values.

    I'm not sure if any of you personally own a t2i(550D), but if you do would you mind confirming what the exact mm are for the lower rail. I'm sure once i have the lower rail I can use two objects at different distances to determine the upper rail. I know the lower rail should be the easier one to figure out but for some reason I just keep getting in that range but never a precise value.

    Thanks!
  5. #5
    Users Country Flag
    Join Date: Aug 2008
    Location: Netherlands
    Posts: 1,740

    Hi and welcome to the forum,

    To find your setting you should measure H in wikidatabase for you camera body and add 13mm for offset of camera plate to reference point of vertical rail. H + 13mm offset of NN4 gives you the LRS = Lower rail setting.

    Then use Smooth method to check it. This is a method to correct misalignment of sensor in camera body and production differences in Lenses and Bodies. Pitch down to -15°, you should see the corner of the rotator. Take your shots around and stitch. I make a mov file in PTGuiPro and move down to the tripod to check the circle of the rotator.

    I personally use a 350gr hard paper cut out to 9cm diameter. Cut out the center screw - 7mm - and the two anti twist screws of the lower rail, 5mm. I place the paper on top of the rotator below the lower rail. But I am testing different camera bodies, that's why I use it.

    http://www.easypano.com/forum/displa...1&TopicID=4162

    Simple rules: the tooth cuts to the right, move the camera to the right on lower rail, it cuts to the left, move to the left. mm by mm. Once you think you found your setting - round circle - , re check by moving 1mm to the right, the tooth should cut to the left. One mm to the left should show a tooth cutting to the right.

    Just tested all this yesterday afternoon with a new user of NN4 to find his settings for Canon body and lenses.

    Once again, anybody having problems in NL to use NN Equipment and find out settings or having problems with stitching might contact me and meet me in the Hague on a friday afternoon or at the weekend. You can also have a look at the whole range of equipment from NN3 - M1-L, R1, complete PoleSeries and accessories and test it all of it with your own equipment. Our Nikon Friends can try a lot of lenses as well, Fisheyes 10.5 shaved, 16mm, Sigma 8mm/f3.5 and Samyang 8mm/f3.5. I will try to answer your questions about rubber rings, washers etc that come with your equipment and check the equipment you bought form your local dealer for everything you need.

    For nothing, the only thing you have to spend is your time to visit me. My input to get you on the road.

    Heinz
    Last edited by hindenhaag; 03-24-2012 at 12:31 AM.
  6. #6

    Quote Originally Posted by PanoArchitect View Post
    I'm not sure if any of you personally own a t2i(550D), but if you do would you mind confirming what the exact mm are for the lower rail.
    The plumb line method of setting the lower rail is obviously sensitive to errors in the levelling of the panohead. A slight tilt of the vertical axis of rotation will result in an offset of the entrance pupil, but this is unlikely to amount to more than a mm or so. Rotating the upper and lower rails by 180 degrees and rechecking will reveal any significant tilt error. The needle and card sight is a much more accurate tool: if you set the lower rail such that the entrance pupil maintains its position when the upper and lower rails are rotated through 180 degrees, even gross tilt in the vertical rotation axis doesn't affect the results. And of course you can also check that the entrance pupil maintains its vertical position at the same time.
    .
    Given the variable nature of the entrance pupil in a fisheye lens, and tolerance errors in disassembling and assembling the equipment, absolute precision is neither to be expected nor necessary. I have shot panoramas with the settings wildy awry (accidentally and deliberately) and still managed to get a perfectly good stitch. But this is not to say that it's not important to get the setup as good as you can. There's no reason to suppose that anybody else's settings will be any better than your own for your kit. The proof of the pudding is in the eating: shoot some panoramas. However, if they don't stitch properly, then it won't necessarily be the settings that are at fault - unskilled use of stitching software can also be a potential cause.
    .
    John
  7. #7

    Quote Originally Posted by hindenhaag View Post
    Hi and welcome to the forum,
    To find your setting you should measure H in wikidatabase for you camera body and add 13mm for offset of camera plate to reference point of vertical rail. H + 13mm offset of NN4 gives you the LRS = Lower rail setting.
    Heinz
    Do you just mean wikipedia? What exactly is the 'H' value. I assumed you meant one side of dimensions but it didn't make sense with the dimensions of the 550D and the numbers I have for the lower rail. Could you possibly post a link to the database that has the H value?

    PanoArchitect
  8. #8
    Users Country Flag
    Join Date: Aug 2008
    Location: Netherlands
    Posts: 1,740

    Ups,

    sorry forgot to place the link: http://wiki.panotools.org/Entrance_Pupil_Database

    H: measure from bottom of camera body to Camera lens release pin aside of lens release button, the small silver pin.

    Some more links:

    http://michel.thoby.free.fr/Fisheye_...the-pupil.html

    http://www.vrwave.com/panoramic-lens-database/

    Heinz

    BTW: Good morning John early morning bird as well...
    Last edited by hindenhaag; 03-24-2012 at 11:54 PM.
  9. #9

    The entrance pupil database is on the PanoTools wiki at http://wiki.panotools.org/Entrance_Pupil_Database

    John
  10. #10

    Hello PanoArchitect,

    There is no real need to be concerned about the dimensions (numbers).
    The important thing is that your camera/lens combination rotates about this point in the front of the lens where the incoming rays theoretically meet, which is called by various names such as Entrance Pupil, No Paralax Point (NPP) or Nodal Point (not really correct as the NP has a specific definition in lens optics).
    As you can see from the link in my initial response, this is not a point in fisheye lenses and as a general rule of thumb the gold ring is a very good starting point.
    I used to use a Sigma 8mm on my Nikon before switching to the 10.5mm and found that setting it up at the gold ring worked just fine.

    John's point about the vertical axis of rotation is particularly pertinent as any tilt will give different values on the lower rail.

    As mentioned in a previous thread on this forum, I do not believe that the odd mm is important although it is best to get the set up as accurately as possible.
    I did some tests with a Nikon 10.5mm fisheye and found that I got just as good panoramas with the axis of rotation of the NN both 10mm in front and behind the gold ring.
    The only difference was that PTGui returned "good" for these two displaced sets of images instead of "very good" at the gold ring when Optimising showing that you will get a better result if the setup is correct, but for most applications it is the visual result that is important and it would appear to me that your setup is good to go.

    Enjoy making panos, Hugh.
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