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Need Help Please (R10 + Rokinon 8mm II)

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  • Need Help Please (R10 + Rokinon 8mm II)

    I've been shooting 360 panos for the last year or so and was using a Canon Rebel T4i and an 8mm Sigma with the R10. I had zero issues with it. Now I'm trying to shoot 360 panos with my Nikon D750 and an 8mm Rokinon (second gen) but I think I'm doing something wrong. The panos are now showing a blank space at the top (the zenith, I believe?). Is it something I'm doing wrong with mounting the camera on the R10 or is it maybe something I'm not doing right in PTGui?

    I've attached the pano itself, as well as screenshots of the problem areas. I'm also including one of the four pictures I took for the pano. As you can see, it includes a lot of the ceiling area but not as much of the floor. And when I add the mirror ball in Photoshop (to cover the tripod area) it's not big enough to cover that space. I wasn't having any of these issue with the Canon/Sigma so I'm wondering what I'm doing wrong now?

    Any help and recommendations would be immensely appreciated!
    Last edited by JumperNoah; 05-18-2017, 11:39 PM. Reason: R10, Nikon D750, Rokinon 8mm

  • #2
    Do you have the version of the Rokinon lens that has a removable hood and have you removed it when shooting this panorama? If not, then the vertical angle of view will be limited by the petals of the hood to something like 140 degrees. If there's no hood, then the vertical angle of view might be limited in PTGui by an inappropriate crop circle setting. You should be able to get a full 180 degrees with the crop circle correctly positioned. The hfov ought to be around 150 degrees (portrait orientation) so only 3 images are required for a full 360 panorama.

    John

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    • #3
      Originally posted by John Houghton View Post
      Do you have the version of the Rokinon lens that has a removable hood and have you removed it when shooting this panorama? If not, then the vertical angle of view will be limited by the petals of the hood to something like 140 degrees. If there's no hood, then the vertical angle of view might be limited in PTGui by an inappropriate crop circle setting. You should be able to get a full 180 degrees with the crop circle correctly positioned. The hfov ought to be around 150 degrees (portrait orientation) so only 3 images are required for a full 360 panorama.

      John
      Hi! Thanks for replying to me. I have the second generation version of the lens and, yes, the hood is removable but I never take it off because it's completely invisible and I still get corner-to-corner coverage since it's a rectilinear fisheye. So I don't think the hood is the issue. Any other suggestions that come to mind?

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      • #4
        Originally posted by JumperNoah View Post

        Hi! Thanks for replying to me. I have the second generation version of the lens and, yes, the hood is removable but I never take it off because it's completely invisible and I still get corner-to-corner coverage since it's a rectilinear fisheye. So I don't think the hood is the issue. Any other suggestions that come to mind?
        Is this the f2.8 or f3.5 lens? There are so many variants of the Samyang lenses, it's hard to find definitive information and sample images. If you have, as you say, full coverage corner to corner, then this would be typical of an APS-C image where the diagonal angle of view is 180 degrees. But on your full frame camera, I would expect there to be vignetting at the visible edges of the image circle. It would be nice if you could upload somewhere the set of 4 D750 images for your panorama so that I can understand what's going on a bit better.

        John

        Edit: Is it possible the camera is automatically selecting DX mode as a result of attaching a DX lens? I'm a Canon user myself, so I'm not really familiar with the quirks of the Nikon system!
        Last edited by John Houghton; 05-23-2017, 12:45 AM.

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        • #5
          Originally posted by John Houghton View Post
          Is this the f2.8 or f3.5 lens? There are so many variants of the Samyang lenses, it's hard to find definitive information and sample images. If you have, as you say, full coverage corner to corner, then this would be typical of an APS-C image where the diagonal angle of view is 180 degrees. But on your full frame camera, I would expect there to be vignetting at the visible edges of the image circle. It would be nice if you could upload somewhere the set of 4 D750 images for your panorama so that I can understand what's going on a bit better.

          John

          Edit: Is it possible the camera is automatically selecting DX mode as a result of attaching a DX lens? I'm a Canon user myself, so I'm not really familiar with the quirks of the Nikon system!
          It is the f/3.5 version. And yes, if I shoot in FX mode you have vignetting/non-coverage all around the image, so what I do is put the camera in DX mode so that it'll fill the entire frame in DX mode, corner to corner. I've attached the four images to this reply so you can see what they look like.

          And this is the lens I'm shooting with: https://www.bhphotovideo.com/c/produ...D_Fisheye.html

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          • #6
            Originally posted by JumperNoah View Post

            It is the f/3.5 version. And yes, if I shoot in FX mode you have vignetting/non-coverage all around the image, so what I do is put the camera in DX mode so that it'll fill the entire frame in DX mode, corner to corner. I've attached the four images to this reply so you can see what they look like.
            Thanks for the images.. They are exactly as I would expect from a DX/APS-C format camera, and indeed the product blurb at the B&H link does say that the lens is "for use with APS-C format DSLRs". You therefore only have 148 degrees vertical fov and cannot avoid holes at the zenith/nadir. However, if you remove the lens hood and select FX mode then you can increase the vertical FOV . You specify the lens as a circular fisheye in PTGui and set a suitable crop circle and use additional masking to obtain the maximum clear image. That should enable you to avoid the hole at the zenith.

            John

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            • #7
              4 shots around. remove hood and use FX mode. Perfect setup!
              Fanotec
              We listen. We try harder.

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              • #8
                Just picked up on this thread and see you already have good advice from Nick and John and just to reinforce this, these panoramas are shot with 4 shots round on a D800 + Samyang 8 mm on an R1 tilted upwards at +7.5 and PTGui stitches perfectly almost every time with a "very good" and closes the zenith beautifully without any further intervention on my part:
                https://www.keithprowse.co.uk/the-al...on-experience/

                The D800 does have a 5:4 format option which still give the necessary coverage and reduces the size of the files a little, but I stick with the FX format in case I forget to change it back after shooting panoramas.

                There is a hole at the nadir, but this is smaller than the panorama head.

                If I need to fill the hole at the nadir I pick the camera up, still on the tripod, and position it approximately where I took the shots round and take a shot vertically down then use PTGui's Viepoin Correction:
                https://www.ptgui.com/examples/vptutorial.html

                I have not filled the nadir in these panoramas for a number of reasons:
                More often than not I would be set up over a vacant chair or steps so did not have a flat area for using the View Point correction,
                I was trying to be as inconspicuous as possible and keep out of the guest way so picking up the camera and tripod and holding it horizontal was not really an option and,
                perhaps the most important of all, the floor and carpet was not always a clean as it could be and it would not have been good to draw attention to food stains etc.!

                I trust that you are now up and running and getting great results.

                Comment


                • #9
                  Originally posted by nick fan View Post
                  4 shots around. remove hood and use FX mode. Perfect setup!
                  Thank you SO MUCH!!!! This solved my issue perfectly. I didn't realize how much coverage I was losing by shooting in DX mode. Since shooting with a crop sensor (Canon t4i + 8mm Sigma) didn't give me any issues before, I didn't think it would be any different than setting my Nikon to DX mode.

                  Comment


                  • #10
                    Originally posted by Hugh View Post
                    Just picked up on this thread and see you already have good advice from Nick and John and just to reinforce this, these panoramas are shot with 4 shots round on a D800 + Samyang 8 mm on an R1 tilted upwards at +7.5 and PTGui stitches perfectly almost every time with a "very good" and closes the zenith beautifully without any further intervention on my part:
                    https://www.keithprowse.co.uk/the-al...on-experience/

                    The D800 does have a 5:4 format option which still give the necessary coverage and reduces the size of the files a little, but I stick with the FX format in case I forget to change it back after shooting panoramas.

                    There is a hole at the nadir, but this is smaller than the panorama head.

                    If I need to fill the hole at the nadir I pick the camera up, still on the tripod, and position it approximately where I took the shots round and take a shot vertically down then use PTGui's Viepoin Correction:
                    https://www.ptgui.com/examples/vptutorial.html

                    I have not filled the nadir in these panoramas for a number of reasons:
                    More often than not I would be set up over a vacant chair or steps so did not have a flat area for using the View Point correction,
                    I was trying to be as inconspicuous as possible and keep out of the guest way so picking up the camera and tripod and holding it horizontal was not really an option and,
                    perhaps the most important of all, the floor and carpet was not always a clean as it could be and it would not have been good to draw attention to food stains etc.!

                    I trust that you are now up and running and getting great results.
                    Thanks for the detailed reply! Nick's solution actually fixed my problem. I'm glad I didn't have to return/exchange the R10!

                    Comment

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