PanoTools:
Re: entrance pupil - nodal point
Erik Krause 2004-Nov-13 00:08:20
On 12 Nov 2004 at 20:50, Dave 360texas.com wrote:
> When viewing though the 8mm FC-E8 fisheye glass front at my pointed
> up pencil is also pointed up.
This one is an adapter. It only changes field of view for the lens it
is mounted on and in technical terms it is a concave lens which never
reverses the image. The lens it is mounted on reverses the image like
*any* photographic lens.
> When viewing through my Nikormat film SLR 50mm 1:1.4 lens, at my
> pointed up pencil - the image is point down. meaning that the image
> is inverted somewhere inside the lens, most likely at the iris
> mechanism set at F16.
This is the usual point where the lens constructor places the iris
because this is the only point where the iris don't cause vignetting.
The iris can be placed at any other point without changing optical
geometry (and in fact is often in zoom lenses, because the point
where the center rays cross the optical axis moves while zooming).
best regards
--
Erik Krause
Ressources, not only for panorama creation:
http://www.erik-krause.de/
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