Re: [Rollei] Re: Rollei panorama head

[Carlos Manuel Freaza <cmfreaza]

Mr. Knoppow, I wrote and I write that I always learn
with your technical answers. Thank you very much.
All the best
Carlos
 
- --- Richard Knoppow <dickburk  > escribió:
> 
> ----- 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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