D300 + Nikon 10.5 fisheye

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  1. Re: D300 + Nikon 10.5 fisheye

    #16

    The exposure really are the same. Only whitebalance was changed in camera raw. Perhaps it's because of the very unregular illumination in my room (it's a small but long room and there are spotlights in it pointing at my desk, leaving the rest of the room dark. It was also becoming dark when I took the pics, so no daylight illumination was apparent.

    Just one more thing...
    According to this table the entrance pupil of the nikkor 10.5 fisheye is located at +/- 46mm from the lens base. If I measured that correctly it should be in front of the golden circle, leaving the upper rail setting at about 90mm...
    Do you have any idea what the distance change is of the entrance pupil of a (this) fisheye when the light is coming in straight or at a 90 (well almost) degrees angle?

    I have read the entrance pupil changes with the change of the aperture as well, do you know if this is true/has any notable influence?

    Thank you again for all the great advice!
    Greetings, Wim.
  2. Re: D300 + Nikon 10.5 fisheye

    #17

    The position of the entrance pupil for rays at 90 degrees to the lens axis can be seen just by looking at it, like this:



    Likewise - by looking, I would estimate the on-axis position to be roughly 3mm or so behind the gold band. I haven't measured it.

    The entrance pupil IS the aperture, or rather the virtual image of it formed by the lens elements in front of it. If you open up the aperture, something else might then limit the effective aperture, and that then becomes the entrance pupil. With the lens wide open, the imaging of near objects can become fuzzy and out-of-focus. With no sharp edges, the parallax effects become rather diffuse and less of a problem.

    John

  3. Re: D300 + Nikon 10.5 fisheye

    #18

    John,

    Valuable info again...
    I really think you should write a book or so on this topic, you seem like a walking pano-encyclopedia.
    You surely would sell at least one book... to me :-)

    Greetz, Wim.
  4. Re: D300 + Nikon 10.5 fisheye

    #19

    Hi John,

    I've looked again at the stitch you've made from my images... I cannot find any stitching errrors...
    It's quite amazing you got this all together. Did you have to do many handwork or has this been done (semi)automatically by PTGui?

    I have been experimenting with the optimizer, the results are getting better, but not as perfect as your stitch.

    And... lens parameters, are they the same for all lenses (well all of the same type, like my 10.5 nikkor) or does that change for each one?
    If it's the same it would be a good idea to make some sort of database for those parameters.

    Greetz, Wim.
  5. Re: D300 + Nikon 10.5 fisheye

    #20

    You hadn't had a chance to react on the previous post and here I am again... :-) I should be sending you a bunch of flowers or so to thank you, but I suppose you live somewhere on the other half of the planet... :-)


    >When you set up the pano head to avoid parallax, you therefore adjust the camera position to suit the angular position where the seam will be located. So for 6 shots around, the yaw increment is 60 degrees and centre of the overlap between two adjacent images will be at 30 degrees to the lens axis. So to eliminate parallax at the image join, you arrange for the camera to rotate about the position that the entrance pupil is in for 30 degree incident rays.

    => Can you try to rephrase this for me? Seems like inportant info and I don't really get it.
    Thanks!
  6. Re: D300 + Nikon 10.5 fisheye

    #21

    I was reacting as you posted the last item:

    The stitch I produced was directly out of PTGui without any postprocessing, but was not a completely automatic stitch. There was intelligent manual intervention to improve the chances of a good output. The automatic control point generator ofen doesn't place control points with an ideal distribution along the overlap areas. It has difficulties matching up the images in the more distorted areas near the corners. A good spread of control points is needed to enable the optimizer to accurately correct the lens distortions. It can only work out appropriate lens parameters that align the images in the corners if there are control points there. So it's a good idea to do a quick check to see that the control points look reasonably ok if stitching as not gone perfectly well. If not, you can place extra control points in areas where there are alignment (stitching) errors and hope that the optimizer will coax those areas into better alignment. Of course, if you have evaluated good lens parameters in a previous project, these can be used in future projects and can be applied conveniently with a template file. The optimizer doesn't need to work them out all over again and so a well distribued set of control points is not then so important.

    I imagine that lens parameters should be the same for each model of lens, but they will vary according to the sensor size in the particular camera the lens is used on. Also, a crop applied to the image (as is commonly done with circular fisheyes), will also change the lens parameters. The shift parameters d and e need to be optimized as they are not constant - probably not even for the same lens on the same camera for different shoots.

    Panoramas taken in small rooms with more-or-less blank walls and ceilings are not easy to stitch perfectly. Some people create artificial features for control points by sticking bits of tape on the walls (to be cloned out of the final image). You should have an easier time with larger venues and outdoor scenes, and with nothing very close to the camera, parallax effects will be largely eliminated.


    As to the entrance pupil clarification requested:

    If you shoot a panorama with 6 shots around, the yaw increments by 60 degrees for each shot. It follows that the seams where the images join are every 60 degrees too (there being 6 in 360 degrees). So if you imagine facing straight ahead at yaw position 0 for the first shot, the two joins to the adjacent images will be made at 30 degrees to the left and 30 degrees to the right, i.e. at 30 degrees to the lens axis pointing straight ahead. It's at this part of the image that we don't want to see any parallax effects that will interfere with the image blending and prevent a seamless join. Given that the entrance pupil moves forwards as we move away from the lens axis, it's the entrance pupil position corresponding to the 30 degree direction that is the point about which the camera should be rotated. The entrance pupil will then be in the same position for each overlapping shot, and features in the vicinity of the seam will not be affected by parallax.

    To look at it (literally) another way, if you position yourself in the panoramic scene precisely at a point where one of the seams will eventually be placed when the images are stitched, e.g. 30 degrees off-axis in the first shot, then you need to see the entrance pupil in the lens occupy exactly the same position for the first shot and also for the next shot (you will be on the right of the first shot and the left of the second shot). If the entrance pupil is in the same place for the two shots, then parallax will be eliminated at that point where the images join. This is the basis for my method of setting up the pano head correctly, which I referred to earlier in http://www.johnhpanos.com/epcalib.htm. It only takes 10 minutes or so to set up the head this way.

    John
  7. Re: D300 + Nikon 10.5 fisheye

    #22

    Wow guys I hate to interrupt a very interesting conversation but John I am almost a complete novice and you sound like someone that can give a few quick pointers on the proper workflow to create HDR panoramas.

    Should I shoot RAW?
    Do I mege to HDR first or do I stitch the pano first?
    etc, etc.

    Again, I apologize for butting in and thanks in advance for any pointers you might be able to give me.

    Jeff
  8. Re: D300 + Nikon 10.5 fisheye

    #23

    Jeff, Shooting RAW is the preferred option. It gives you the maximum flexibility and quality. You can easily make corrections for chromatic aberration, white balance and vignetting, depending on your RAW converter. If speed of shooting is important, it can sometimes be better to use JPEG to avoid hold ups due to buffer filling up on write-outs to the memory card.

    For HDR, merging images before stitching is the simplest technique. Sitching and then merging enables you to preview the entire panorama when tweaking the parameters, which should be an advantage. One disadvantage is that the blender may not place the seams in exactly the same place for each stitch, and this can occasionally lead to mismatches. You should do your own tests and see what works best for you.

    John
  9. Re: D300 + Nikon 10.5 fisheye

    #24

    Hey Jeff,

    As you may have read, I'm not the expert here, but I have had good results with the HDR function of PTGui. Just shoot your brackets in RAW, convert them (make sure whitebalance, CA is ok) to jpeg and open them all together in PTGui. If you have shot them from a tripod (I think you will have) you best 'link' the branckets when PTGui asks you. That means that PTGui does not try to align the bracketed images but merges them together like they are. You really need the image brackets to be perfectly aligned for that, but since you were using a tripod that should be the case.

    After that workflow is quite the same as a normal image I suppose. I do have better stitching results using HDR than I have with single shots. How placing of control points by hand is done with all those images I don't know, John any idea?

    See you!
    Wim.
  10. Re: D300 + Nikon 10.5 fisheye

    #25

    Oh, John, I get it it now!
    Lot's of the fisheye entrance pupil confusion has been cleared out here. Thanks.
  11. Re: D300 + Nikon 10.5 fisheye

    #26

    I am breaking my head here over this Nodal Ninja...

    I'm taking pics, turning 'em around in photoshop, comparing, adjusting, agian again... doesn't seem to be working to get the lower rail setting good.

    Two problems: I keep getting left/right shift (so perpendicular to the lower rail), but I have checked evenrything over and over: camera is perfectly straight on it's mounting plate, that one is perfectly straight on the upper rail. I set that one on exactly 90 degrees etc... and that shift will not go away.

    Second thing I have noticed is that my nodal ninja does not turn around (the cross on) the knob perfectly... If I measure the distance from the vertical arm to the centre of the cross (yes the cross in perfectly centered on the know, I've measured it), then I rotate the NN to the different click stops I measure a difference of 0.5 to 1mm.

    Another thing I am confused about is: if I take two nadir shots (one at 0 degrees, one at 180 degrees), and I turn one of them 180 degrees in photoshop, should the surroundings align well? The knob alligns quite oke (except for the small shift I talked about) but the surroundings are far off...
    Or the other way around if I stitch those with PTGUI, I get fairly good results for the surroundings but the knob is visible twice (and also the small sawblade pattern, but that I from the shift if I have read your pages well John).
    Have included that pic.

    I'm really freaking out here ;-) somebody help! :-)
  12. Re: D300 + Nikon 10.5 fisheye

    #27

    This one is the same as above but from 6 shots and stitched...
  13. Re: D300 + Nikon 10.5 fisheye

    #28

    Wim, The first of your sample images shows parallax shift of the knob with respect to the background. You therefore need to move the vertical arm inwards towards the knob by 3-4mm. Also, you need to rotate the camera clockwise a smidgin (as viewed looking at the top of the camera i.e. the hot shoe).

    John
  14. Re: D300 + Nikon 10.5 fisheye

    #29
    Users Country Flag
    Join Date: Apr 2008
    Location: Hong Kong
    Posts: 2,386

    hi wim,

    the parallax shift is related to distance. the close the subjects, the more pronounced the shift. Since fisheye lens do not have fixed NPP and parallax is distance dependent, it is very difficult get a parallax free pano in a small crowded place. you should calibrate the pano head for scenes that you are going to take. Why not try easier ones such as a garden or a living room pano first? after you get some experience and enjoyment, you can come back to tackle the more challenging scene.


    Nick

    PS since the rotator tension knob is very close (relative to other subjects) to the lens, I suggest you to ignore it. You should be able to align the NPP using external references only. Use you current setting as a starting point. Align the NPP on the upper rail first, then the lower rail setting according to Manfrotto 303 SPH's manual. See page 5-7.
    http://services.manfrotto.com/303SPH...SPH_manual.pdf



    Fanotec
    We listen. We try harder.
  15. Re: D300 + Nikon 10.5 fisheye

    #30

    Hi guys,

    => Bringing vertical arm back 4mm: check.
    (That brings me back to the original 59.5 mm ;-) )

    => Ignore the knob: check.

    => Turning the arm clockwise a smidgin (what a funny word :-) ): check.

    Result: A stitch of the same small room with only one tiny little stitching error (perhaps with the hint from John on CP optimization, I can remove it)!
    Think I will glue these settings, to never loose them again :-)))



    On another forum Matt from 360precision said: "The D200/10.5 setting for six shots is 83mm and 86mm on the D300. Matt 360Precision.com" (http://www.panoguide.com/forums/qna/4486/)
    I suppose he's referring to respectively the lower and upper rail settings? But without the CP I suppose. Does anyone know when the table of NN settings on the website has gone and when it will be back? Then I'll be able to check if these match.

    See you and again thanks, looks like this is the busiest topic on the forum :-)

    Best regards, Wim.
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