On Friday, August 31, 2001, at 08:40 BC, Santiago Ribas wrote:
> On 31.08.01 14:24, "Mark Doolittle" <email@hidden> wrote:
>
>>> and , Ted Oliverio at email@hidden wrote:
>>>> I'm not sure about your particular camera or lens combination, but
>>>> I've
>>>> never seen a rig where what you describe is true.
>>>>
>>>> Typically, the nodal point is at the very-very front of the exposed
>>>> surface (i.e., film or CCD). We typically use The Parallax Test to
>>>> find
>>>> this spot, as it only takes a few seconds.
>>
>> With my Nikon N90/16mm fisheye, the nodal point is within a few
>> millimeters
>> of the farthest front edge of the lens. Found by setting a light
>> stand a
>> couple feet in front of the lens, lining it up with a vertical across
>> the
>> room, and then sliding camera forward/backward until the light stand
>> and
>> vertical do not move relative to one another when the camera is
>> rotated on
>> the tripod. Is that the "Parallax Test"?
>
> My process is easier:
>
> I have measured the azimuth of the sun during the first day of the
> summer
> every 10 minutes and converted to radians, my camera facing south. By
> dividing the Tilt angle between the sun and the front plan of my 8mm
> fisheye and mulltiplying by 180/pi radians for every 20 minutes
> (2x10minutes) I have the average angle of the sun height in the sky, and
> consequently I can find the horizontal distance of my nodal point from
> the
> front plan of my 8mm fisheye to my feet (I don't use tripod) wich is
> aprox.
> 0.08m
>
> Santiago
>
>
> Interesting use of the word "easier" ;D
Thanks,
Ted
