wwp@yahoogroups.com:
Re: nodal point
Erik Krause 2005-Aug-06 12:53:00
Am Friday, August 05, 2005 um 23:39 schrieb wbr:
> More thoughts about np , I have no other proof than my own experience and
> pano's. For those interested look here:
>
> http://www.abolais.nl/np-E10/np-calculation.jpg
This might or might not be true for some lenses. The front lens
diameter is not exact enough to determine nodal point, and it might
be totally useless. You don't know whether the lens is designed for a
larger sensor, f.e. or it might be that large to obtain a large
aperture at the long end, not mainly for a big field of view at the
short end.
Furthermore the nodal point for a fisheye lens depends on the angle
of view - it has no exact location for all distances from the image
center. See here for details:
http://michel.thoby.free.fr/Liste-experiments1.html Look especially
for the Sigma 8mm graph (Sigma 8mm -> Results -> graph)
To calculate the exact nodal point from a given lens for which you
don't know the exact internal structure and the used glasses is
impossible. If you would know these things, you could use a lens
modelling programm like WinLens from Linos Photonics or OSLO. But
luckily it is easy to determine it...
BTW.: these type of technical discussion is better done on
#removed# - it's more knowledge there. The WWP list
is dedicated to discussion of the WWP events...
best regards
--
Erik Krause
Offenburger Str. 33
79108 Freiburg