Re: [Rollei] Re: Rollei panorama head

["Richard Knoppow" <dickburk >]

- ----- Original Message ----- 
From: "Eric Goldstein" <egoldste  >
To: <rollei  
Sent: Saturday, May 10, 2003 9:07 AM
Subject: [Rollei] Re: Rollei panorama head


> Eric Goldstein <egoldste  > escribió:
>
> >> I too am a user of the rollei pan head... I find it
> >> tends to work better
> >> with the 75 mm lens on my 'cord III than the 80 mm
> >> on the 2.8C; the frames
> >> seem to match a bit closer...
> >>
> >> Does anyone have any other experience with this
> >> accessory?
>
>
> Carlos Manuel Freaza:
>
> > About the frames a bit closer, I think it depends
> > subject and distance to subject.
>
>
> Good point Carlos. I guess I am assuming the most users
are shooting distant
> objects   horizon line is usually present
somewhere, as in
> your shot...
>
>
> Eric Goldstein
>

  One problem I've found with shooting panoramas with the
Rollei head or just in general with multiple images from a
standard camera is the mismatch at the edges of the pictures
due to the "distortion" from the rectilinear geometry of the
lens.
  If you photograph an array of spherical objects, say golf
balls, you will find those at the corners of the picture are
egg shaped. If the picture is viewed from the correct
distance with one eye, the golf balls will look round again.
This is because of the diminishing perspective when viewing.
This is also the cause of the "distortion" when using wide
angle lenses. It really isn't distortion, it comes from
viewing from the wrong distance. If an array of circles on a
flat surface is photogrphed they will be reproduced as
circles since in both life and when viewing the photo the
perspective will make them appear somewhat eliptical. This
is why the "distortion" does not have any effect when
enlarging or projecting.
  The effect when combining photos for a panorama is to
distort the shape and angles of intersection at the edges.
The effect could be eliminated by projecting onto paper held
on a spherical surface or by using a special corrector lens
giving the same effect. This correction is easily done using
a computer but not easy for photographic printing.
  I am _very_ suspicious that the beautiful examples of
panoramic photos shown in the Rollei instruction manual were
actually photographed with a rotating panoramic camera, they
match too perfectly.
  The mismatch can be seen in Carlos's photo but is not too
obvious because of the subject matter and also the
outstanding job of matching the tonal rendition of the
sections. It can, however, be seen in the railing.
  As for the use with a 75mm vs: an 80mm lens, the 75mm
might be better because of larger overlap but it may also be
that the panoram head turns closer to the rear nodal point
of the shorter lens. I suspect error from any mis-match here
is very slight, if it exists at all.
  Note, that since the lens moves with regard to the swivel
point of the adaptor when the distance of focus is changed
that the match with the nodal point will not be as good for
close objects as for distant ones. Also, the overlap will be
less since the effective viewing angle of the lens is less
with close objects (except for front element focussing
lenses or when a close up diopter attachment is used).
  This is a remarkably good example of a panoram photo.
- ---
Richard Knoppow
Los Angeles, CA, USA
dickburk  

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