Re: 220 VR questions

[Dan Slater <dslater@xxxxxxxxxxxxx>]

Bill Glickman wrote:

> Hi, I am new to the Pan list...
>
>      I just bought a Seitz 220 VR.  I have been testing it for the past week
> and trying to perfect the use of it before I leave on a long Photo trip on
> 6/16.  I have the followings issues that possibly more experienced users
> could be so kind to assist me.
>
> 1.  The h value (H-H) which seems to be the distance between the two nodal
> points of the lens.... this information seems impossible to get for the
> Mamiya 645 lenses.  Seitz does not know the values and Mamiya either won't
> release the information or does not comprehend exactly what is being asked.
> I am wondering why Seitz even designed and released the Mamiya lens board
> when these values are unknown by them?  Peter Setiz recommended using the
> Hassy values which are in the manual, however, the variance in lens makers
> values for equal fl lenses for this value varied so much between the 35mm
> lenses, like Nikon, Leica, etc.... I felt doing this would be a total random
> guess which could be so far off it would make things worse?
>
> 2.  Does this h value offer no benefit when subjects are far?
>
> 3.  Mr. Seitz explains the need to nail the fl of each lens down to +/- .05
> mm.   With my 150 and 300 mm this process was tedious but, it seems to have
> worked.  I shot a wall about 150 ft. away.  I measured the aspect ratio of
> the wall, and then measured the vertical height on film and calc. what the
> horizontal needs to be to maintain the same aspect ratio.  This was fairly
> effective.  However, on wider angle lenses, 80 and 35mm, this was not so
> easy... image distortion makes measurements too difficult to be this
> accurate.  Mr. Seitz said shoot letters.... so I shot letters on buildings,
> the largest letters I could find.... and it is way too difficult to
> determine within .05mm which letters look best.... they all look good when
> you get down to a few tenths of a mm?
>
> 4.  The test images I shot all appear soft on film.  I was a disappointed
> with the image quality.  It did not come close to what a MF camera can
> produce.  Do other people experience this also?  I was told by a few users
> that rotational cameras are not that sharp for the obvious reasons.  Mr.
> Seitz said a MF lens will never be as sharp on a rotational camera vs. a
> still camera?  I am wondering how much worse the image really gets.  Does
> using smaller slits help?  Any input on this would be helpful...  I was
> planning on big enlargements, and now am doubting the possibility of doing
> such.
>

A panoramic camera is capable of producing as sharp if not sharper images than
still cameras. The lens need only be highly corrected for a small part of the
image. This is one of the reasons that panoramic cameras are often used for very
high resolution aerial (U2, SR71) and space (Corona, Apollo lunar pan camera)
reconnaisance applications.

My experience with the Hulcherama 120 using a 35 mm Mamiya lens is that the
image is very sharp, ie., line widths well below 20 microns, similar to medium
format cameras. The Hulcherama does not rotate around either nodal point nor is
there any nodal point adjustment for different lenses. The only effect is that
objects closer than about 10 feet are soft.

What is important is that the film travel at precisely the correct speed (ie.,
the focal length setting). The nodal point settings are relatively unimportant
and generally need not be precise. The front nodal point in the Hulcherama is at
least several inches away from the desired location on the rotational axis.

Dan Slater