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wilco23
04-17-2009, 07:48 PM
Hi,

I received NN5 with RD16 last few days ago and does not have much chance to look detail. I have checked all the parts today. Everything is what I expected. I have Manfrotto 300 old type that I purchased last 4 years back. RD 16 is way better than Manfrotto MA300 and all detent intervals are precise.

I have question on nodal point for zoom lens. I have Nikon zoom 16-85mm and I try to googled for nodal point finding procedure and I saw that nodal point will change even if you change the focus point. Is that correct? Does nodal point varies even though you set the zoom at specific setting and try to focus distance object?

Thanks

John Houghton
04-18-2009, 12:58 AM
Zoom lenses are complicated things and there are no general rules for how the position of the no-parallax point varies with zoom and focus setting. The no-parallax point is located at the entrance pupil, which is the virtual image formed of the aperture by the lens elements in front of it. In some lenses, the front elements move forwards and backwards as you focus or zoom. In others they are fixed but internal elements move. All you can say is that the entrance pupil position will probably change with focus and zoom setting. By how much is problematical. You can get a rough idea of how much movement is involved simply by looking into the lens as you operate the controls and seeing the effect on the entrance pupil. To find the no-parallax point accurately, see http://www.johnhpanos.com/epcalib.htm.

John

wilco23
04-18-2009, 08:05 AM
Thanks John,

I want to shoot high resolution panorama. If I buy telephoto, will focusing change nodal point? In telephoto, does it affect parallax point for stitching? I have zoom lens only and I will look for telephoto.

Thanks

nick fan
04-18-2009, 08:46 AM
Thanks John,

I want to shoot high resolution panorama. If I buy telephoto, will focusing change nodal point? In telephoto, does it affect parallax point for stitching? I have zoom lens only and I will look for telephoto.

Thanks


you probably will have 2 different NPP settings for macro and landscape work. Other than that one NPP setting will serve you well.


Nick

wilco23
04-18-2009, 09:06 AM
Thanks Nick. I want to shoot landscape, but extra macro feature will good too. When you said 2 different nodal point setting, it means if I used macro lens like Nikon 105mm f2.8 macro?

nick fan
04-18-2009, 09:33 AM
Thanks Nick. I want to shoot landscape, but extra macro feature will good too. When you said 2 different nodal point setting, it means if I used macro lens like Nikon 105mm f2.8 macro?


I mean if your scene is say 1 meter from the lens, its NPP setting may be different from that used for landscape scene >20 meter away.
There is no need to worry too much. Do some practice and you will see if you need to adjust the NPP setting. :wink:

nick

John Houghton
04-18-2009, 01:17 PM
One thing that is important to remember is that the angle of view of the lens will change when you alter the focus setting. This means that if you shoot rows of images at different focus settings (to get the foreground of a landscape in focus, say), you may need to take account of this in the stitching. E.g. in PTGui or Hugin you need to use different lens parameters for the shots according to the focal length setting.

John