Date sent:        Tue, 28 Jan 1997 17:55:55 +0000
From:             Willem-Jan Markerink 
Subject:          Re: FotoFacts - Scheimpflug
To:               List for Photo/Imaging Educators - Professionals - Students
Send reply to:    photoforum@listserver.isc.rit.edu

On 28 Jan 97 at 7:44, ANDPPH@ritvax.isc.rit.edu wrote:

>                                   Scheimpflug
> 
> The general guidelines for use of swings and tilts with view cameras are:
> 
> To control subject _shape_ only:   Swing or tilt the back
> To control _sharpness_ only:       Swing or tilt the lens and/or the back
> To control shape and sharpness:    First swing or tilt the back to adjust shape
> and then swing or tilt the lens to maximize sharpness.
> 
> It is often possible for a photogrpaher to determine the correct angle of tilt or
> swing for sharpness control by examining the image on the groundglass as the
> adjustments are being made. This trial and error method can be time-consuming,
> especially when the subject does not have bold detail or when the image is dim due
> to a low light level of illumination. Adjustments of the lens or back can be made
> more accuratley and more rapidly if the photographer notes that to obtain overall
> sharp focus, the plane of the subject, the plane of the lens board and the plane
> of the back or filmholder must be either parallel to each other or meet at a
> common point. This is the Scheimpflug "rule" - as stated by Theodore Scheimpflug
> in 1904.
> 
> ... from:  View Camera Technique by Leslie Stroebel

I would like to make an mathematical addition, extracted from the 
(European) Canon brochure on TS-E lenses, 'The Impossible Picture', 
written by three Dutch photographers, published by Canon Europe.

The authors even go as far as stating that the below formula is the 
first publication of such in English literature:

                                   focal length
sine angle of tilt = --------------------------------------------------------------
                              distance of object plane to principal point of lens

As an example they take the situation where the object plane is at a 
(perpendicular) distance of 17.5cm to the lens, while using the 24mm 
TS-E lens.

sine angle of tilt = 24mm / 175mm
inverse sine (or sin^-1) [24/175] results in an required angle of 
tilt of 8 degrees.

The title 'The Impossible Picture' is then explained with the same 
situation for a 4x5" camera. With a 100mm lens one would need a tilt 
angle of 35 degree (inverse sin [100/175]), which would "obscure the 
image by vignetting its contrast, and sharpness would suffer greatly 
from the effect of lens aberrations".

Would love to hear some comments on these notes....is this really a 
first-time publication in English literature? [I must then assume it 
is from either Japanese or German origin]

(PS: people have tried to obtain this brochure in the US, but
apparently this is a Canon Europe item, not available in the US.
Don't bother asking Chuck Westfall of Canon USA, he also can't
provide you with it)
--
Bye,

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If you have any question, remark, comment, want to share some philosophy or just want to express your opinion about these pages, feel free to send email to: w.j.markerink @ a1.nl