R10 accessories - 4 shots, 6 shots, NPP setting
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  1. R10 accessories - 4 shots, 6 shots, NPP setting

    #1

    I've been looking at an R10 as a travel head, the rest of my pano gear is too heavy.

    Shooting a Sigma 8mm f3.5 on a Canon APS-C sensor, I've been happy with 6 shots around at +7.5-deg pitch on an NN5, plus nadir.

    I'd like to replicate this on the R10 with mini rotator. No problem, I see the 60-deg detent ring version.

    ***here is the question***
    However, the R10 quick reference guide refers to a .85 rail setting "for four shots around".
    Likewise, the R10 stop plate 102 product listing refers to "+7.4 4-shots GTP".

    Is this lens ring & stop plate going to be equally fine for 6 shots around? My brain tells me "yes", if the NPP is set it doesn't change with 4 or 6 shots. But then there are some comments from DennisS about a slight sideways offset with this head; would 6 shots tend to make this offset more prominent, making stitching more challenging?

    Thanks,
    Seth
  2. #2
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    6 shots will be slightly different from 4 shots, about -0.15 for the LRP settings. If you just need a stop plate, we can make one easily.

    nick



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  3. #3

    Thanks Nick.

    For now I've ordered the F2106 Arca-Swiss style stop plates, I think those will serve me well as I'm getting used to the R10. Maybe I'll do the inserts in the future... but those stop plates look like good stuff too.

    I'm still a little bit in the dark - why is the 6-shot NPP different than the 4 shot? Does this have to do with the inconsistency of NPP at the edges of this fisheye, as demonstrated with laser pointers at some web site? The 6 shot moves the stiching seams to a different area of the image?
    Last edited by sbloombaum; 08-07-2014 at 12:28 AM.
  4. #4
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    Quote Originally Posted by sbloombaum View Post
    Thanks Nick.

    For now I've ordered the F2106 Arca-Swiss style stop plates, I think those will serve me well as I'm getting used to the R10. Maybe I'll do the inserts in the future... but those stop plates look like good stuff too.

    I'm still a little bit in the dark - why is the 6-shot NPP different than the 4 shot? Does this have to do with the inconsistency of NPP at the edges of this fisheye, as demonstrated with laser pointers at some web site? The 6 shot moves the stiching seams to a different area of the image?
    yes, you already got some idea.
    further reading
    http://michel.thoby.free.fr/Fisheye_...the-pupil.html



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  5. #5
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    Quote Originally Posted by sbloombaum View Post
    I'm still a little bit in the dark - why is the 6-shot NPP different than the 4 shot? Does this have to do with the inconsistency of NPP at the edges of this fisheye
    Seth,
    .
    You are correct that the NPP is different based on the number of shots around you want to use. It has to do with where the seam is in the picture. If you add more pictures, the seam moves towards the center of the image. This can effect where the NPP is and an adjustment may be necessary.
    .
    As to my previous post showing a modified R10 allowing side to side adjustment.
    .
    I approach panoramas as an engineer would. I do not have any stitching issues because my gear is calibrated pixel perfect. I do not know what the lens parameter tab in PTGui is and have never needed to enter individual parameters. Matter of fact, all I do is set the crop circle, auto generate points, add or remove control points as needed then stitch. Sometimes a pano needs more work in pre and post, but for the most part stitching is not an issue.
    .
    Since I take such an engineering approach to panoramas I want to get my rig as absolute spot on as possible.
    .
    The R1/R10 line of pano heads does not always position the center of the lens exactly above the center of rotation. I measured several rings and each was off center one way or the other.
    .
    This does not mean you will not get a good stitch. Modern stitching software does an excellent job of correcting an off calibrated rig.
    .
    I am very fortunate enough to have the tools and skills to fabricate whatever I need. When I was calibrating my monopod rig I noticed all the images were off center. I put the rotator on a tripod and verified the camera needed to shift sideways. I figured out how to modify the R10 to allow this. Hopefully if enough people ask Nick will implement side to side adjustment.
    .
    Side to side adjustment for the R1/R10 is not absolutely necessary. It would, however, help to dial in those last few millimeters to eliminate one more variable in rig calibration.
    .
    Dennis
  6. #6

    Hello Seth,

    This may help explain graphically what Dennis is saying.
    If you go to hugha.co.uk and scroll down to the button with an image of a Sigma 8mm lens (Determining the Nodal Point of a Lens), or use this URL - http://hugha.co.uk/NodalPoint/Index.htm and go near the bottom you will see diagrams of how the NPP moves relative to the angle of the light entering the lens.

    As Dennis says, the position to chose for setting up the lens is where the "join" is between shots.
    4 shots round and you are looking where the rays meet at 90 degrees - i.e. 45 degrees either side of the principal ray
    6 shots round and you are looking where the rays meet at 60 degrees - i.e. 30 degrees either side of the principal ray

    Also, with more shots round you get more overlap so can use the "Mask" tool in PTGui more easily and it is worth noting the the "distortion" caused by the way the NPP moves increases as the angle from the principal ray increases.

    Hope this explains the difference.

    Another consideration is how far away your subject is.
    It is a matter of scale so if your panorama has detail close to the camera then positioning is more critical than if all the detail is some distance away.

    Hugh.
  7. #7
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    Quote Originally Posted by Hugh View Post
    Also, with more shots round you get more overlap so can use the "Mask" tool in PTGui more easily
    Hugh,

    I do not understand this statement. You should be able to use the masking tool just as easily if your pano has 4 or 400 shots. The shot count does not enter into the functionality of masking. I usually use viewpoint correction along with masking to patch the Nadir shot, no matter how many shots around.

    Dennis
  8. #8

    Hello Dennis,

    If you have more overlap then there is more image area to use the "Mask" tool in.
    For example , if you take 4 shots round you only have a small overlap then you are limited to the area you can "Mask" out or in, but if you take 8 shots round with the same lens with much greater overlap then you have much more area you can "Mask" out or in

    I have taken panoramas in very busy places with people moving about quite rapidly close to the camera and having a big overlap allows me to mask out people who appear in two (or sometimes more) images.

    I will post examples if you like.
    Last edited by Hugh; 08-08-2014 at 04:43 PM.

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