PanoTools:
Re: Re: entrance pupil - nodal point
Girolami / Kaleido 2004-Nov-09 11:22:52
Have a look
http://www.kaidan.com/nodalpoint.html
ciao
Giulio
At 10.24 09/11/2004, you wrote:
>Thx for the attached description.
>For me, it`s not clear at all. But if all the measurement for "nodal
>point" and "entrance pupil" to avoid parallax error means the same at
>the end, it is ok for me.
>Is there a picture that could describe it for a visual thinking like
>me?
>
>I tried to translate it to german is it correct?
>entrance pupil -> Eintrittsblende
>nodal point -> Kontenpunkt, optisches Zentrum einer Linse
>
>
>Regards
> Manfred
>
>
>--- In #removed#, "sdubose99" <#removed#> wrote:
> >
> > Manfred, guten tag... for all intents and purposes of producing a
> > panorama images with little parallax, nodal point and entrance
>pupil
> > are the same.
> >
> > Scott
> >
> > The following is from John Houghton in the UK:
> >
> > Nodal point: When you have a lens made up of two or more elements,
> > the resulting combination of lenses will have an effective focal
> > length "f". On either side of the lens will be the two focal planes
> > where objects located at infinity will be focused. If you measure a
> > distance f back towards the lens from the focal planes, you will
> > arrive at the principal planes. In a simple lens, these will
> > conicide, but in a complex lens they will be separated. The points
> > where these principal planes cross the lens axis are called the
> > principal points. These points are also where the nodal points are
> > located. A light ray incident towards the front nodal point will
> > emerge as from the rear nodal point in a direction parallel to the
> > incident ray. In a camera, if the lens is rotated about the rear
> > nodal point, the image will remain stationary on the film located
>at
> > the focal plane. This is an important factor in the design of
> > panoramic cameras in which the lens rotates rather than the camera.
> >
> > Entrance pupil: Somewhere between the elements of a complex lens
> > will be the iris. If you look through the front of a lens, you will
> > see a virtual image of the iris formed by the front elements and
> > this is called the entrance pupil. Likewise, there is an image of
> > the iris formed by the rear elements of the lens called the exit
> > pupil. All light rays passing through the lens pass through the
> > entrance and exit pupils. The front entrance pupil is therefore the
> > centre of perspective of the lens. Rotating the camera about this
> > point will avoid parallax errors.
> >
> > In the context of stitching multiple image panoramas, all the
> > practical methods described for determining the position of the
> > nodal point in fact find the position of the entrance pupil, not
>the
> > nodal point. Since it is the entrance pupil that is required, then
> > the methods give the desired result.
> >
> > --- In #removed#, "manfredgruber"
> > <#removed#> wrote:
> > >
> > >
> > > Hi,
> > >
> > > Can someone explain in easy words what`s the difference between
> > > lens entrance pupil (centre of perspective)
> > > and
> > > nodal point
> > > ? Or is there a good reference somewhere in the internet (i didn`t
> > > find)
> > >
> > >
> > > Regards
> > > Manfred
>
>
>
>
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