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Author Topic: Recommendation for Pano Head  (Read 3606 times)
SeanBK
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« on: April 06, 2006, 03:20:42 PM »
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Hi, Seeking advice to purchase QTVR pano head for my D2x & Hassey. So far RRS & Bogen/Manfrotto QTVR heads seems to be impressive.
Any recommendations to find Nodal point of my 17-55mm F2.8G ED AF-S DX lens. Since Nikon does not supply that info. Is it just trial & error with 4pens standing on a table. @ 2 in front & 2 in back and removing parallax!
  I posted this question in Landscape, but it is sitting idle. I thought M.F guys might have a better suggestion. Lonna may be you can help out.
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Lester
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« Reply #1 on: April 06, 2006, 07:35:51 PM »
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Okay, I will try to help. I got the Bogen/Manfrotto OTVR head and it works great for my 1DsMkII and Mamiya 645 P25 system. To find the nobal point, you just have to set a point in front of you, like a pole, and a point about 25+ feet away, you move the tripod so that the front and back is match in the center, then you turn the OTVR it to the left and right to see the miss aligment. To correct this, you move the camera front and back on the OTVR until everything is match, so when you move it left or right and center, the front pole will match the far object. The left to right movement is usually set at the center of the camera, once this is set, you do not have to move this setting anymore, because it is the center point of the camera. Now that I confuse you, every lenses have a different nobel point.
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BernardLanguillier
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« Reply #2 on: April 06, 2006, 08:37:23 PM »
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I have been using the RRS stuff with my D2x with good results.

http://www.photosig.com/go/photos/view?id=...d=viewportfolio

although I own the 17-55, I have never tried to do panos with it and don't know the nodal points.

I typicall use the 12-24 and 35 mm f2.

I can communicate you some Nikkor lenses nodal points if you'd like.

Regards,
Bernard
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SeanBK
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« Reply #3 on: April 06, 2006, 09:01:19 PM »
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Lester, Thanks for your explanation. I am asked to follow almost the same but slightly modified procedure with 2 sets of points(pens) as explained below. I believe both makes sense, as Nodal point also known as entrance pupil location will change with focal length, so for zoom lens one has to reconfigure it for different zoom (i.e 17mm, 24mm, 55mm....). So Bernard, thanks for your input, but I will be shooting only with 17-55mm zoom my Panos, so I won't need other Nodal point locations. Looks like I may have to settle for RRS, even though they are more expensive than Bogen, but they ARE well made. Love your Pano shot of Mount Fuji. That IS very unusual, as I have seen only ice capped pics of Mount Fuji. Here is explanation with 4 points.

"Adjust for parallax error - to find and correct the parallax error perform the following exercise using the camera, a tripod with panoramic head, a table and four pens (it is easy to use 'marker' pens which can stand by themselves). Arrange the pens as shown in the illustration below. Position the camera on the tripod using the panoramic head so that the near and far pens can be viewed on the camera's LCD monitor at the same time (or viewfinder if using an SLR). The near pens should be as closer than the rear pens.

 
Table seen from above and from the side showing position of pens.
Viewing the camera LCD monitor or SLR viewfinder align the pens and pan the camera from left to right so that the pens move from the left to right side of the camera LCD monitor, note the relative movement between the pens as the camera is panned. Using the panoramic head move the camera backwards or forwards until the relative movement between the pens is eliminated during pan.

 
 
 
 
In this example the camera is too far forward.

 In this example the camera is in the correct postion, the camera is rotated around the nodal point of the lens.
 In this example the camera is too far back."
  I am sorry but illustrations do not go thru'. I hope they still make sense.
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BernardLanguillier
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« Reply #4 on: April 07, 2006, 03:55:03 AM »
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On top of the basic pole alignement method, which has to be done obviously, my personnal recommendation for fine tuning is to check the actual stitchability of the images using the PTgui optimzer function.

When you know you are close the nodal point, take sets of images every mm (of every .5 mm) along the rail, keeping track of which images were taken at which location.

Then just try to stitch, and find the location that yields the smallest stitching error in PTgui.

This assumes that the result will be the same for different scenes, which I cannot garantee, it should be tried.

As a final disclaimer, I have not yet taken the time to test this revolutionary procedure...

Regards,
Bernard
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SeanBK
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« Reply #5 on: April 07, 2006, 08:09:54 AM »
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Thanks Bernard for the detailed explanation. Now after reading up more, I wonder shooting with 17-55mm f2.8 Nikor lens on Nikon D2x would give me more problems, may be I should be buying a different lens?
 I wonder anything has changed/upgraded from this discussion as 9months in DigiWorld IS a real long time.
http://luminous-landscape.com/forum/index....topic=5188&st=0
 and also
http://homepage.ntlworld.com/j.houghton/optitute.htm
  I should be getting more info today, so I will post my findings, but wanted to thank you first.
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BernardLanguillier
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« Reply #6 on: April 07, 2006, 10:00:03 PM »
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No problem.

Generally speaking, zoom lenses suffer from complex distorsion on the wide and long ends. This means that simple distorsion correction software (including stitching softwares) cannot really get rid completely of the distrosion.

This results in some stitching imperfections.

My solution for this is to use DxO on zoom lens images.

Regards,
Bernard
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