Can we, in the present day, appreciate just how much opticians, photographers (some, probably not all), as well as former artillery and naval officers knew when they designed lenses, classic and soft, in the early days of photography (1800's)?
Sony A7
Cosina Cosinon 55mm f/2.8
Nikon Nikkor Soft 1
The soft effect is too strong compared
with early Expressionist/Pictorialist work
The field of lens development for photography was not based on feelings nor emotions nor misunderstandings. No. Not at all. Instead, early designers were able to apply knowledge of material science and math in a way that produced informed, repeatable, accurate solutions. They did this including as it was applied to soft focus photography.
Remember that Herren Petzval und Voigtlander hired naval officers to calculate lens element shapes from the very beginning. Herr Steinheil's optical designs were all based on calculations he'd made. Monsieurs Pulligny et Puyo calculated the chromatic aberration diffusion disk at the point of focus which ultimately led to the les objectifs d'Ariste et le Hermagis Eidoscope. And these guys were not at all unique.
Anyone who ground lenses knew the math and the limitations and opportunities afforded by the materials at hand. Knowledge diffused through the community such that people like Herr Kuhn and Mr. Taylor of Cooke Triplet fame all knew what each-other were doing and why. Letters sent between opticians and interested parties as well as photography club proceedings, lectures, and articles show this was very much the case.
It came as little surprise to me when I recently stumbled across a calculation for optical "softness." The formula came after a long exploration of Expressionist/Pictorialist photography possibilities through the use of lens imperfections. "Softness" designed with purpose.
On Spherical Aberration ~
The primary optical "softening" agent that I've been familiar with is spherical aberration. It came as a surprise to read where the French did not like to use this optical fault.
Biblioteque de la Revue de Photographie by L. de Pulligny - C. Puyo "Objectifs d'Artiste Practique et Theorie des Objectifs et Teleobjectifs Anachromatique", page 20
[Aberration spherique] résulte un épaississement cotonneux du trait qui n’est pas agréable, et on ne peut admettre cette aberration que pour une très petite part à 1 oeuvre de simplification que nous poursuivons. En diaphragmant suffisamment, on peut atténuer a volonté l'aberration sphérique et en laisser juste assez pour qu’elle soit utile dans certains cas où cette réduction du diaphragme est admissible : par exemple, dans
la photographie du paysage...
In English...
[Spherical aberration] results in an unpleasant, cottony thickening of the lines; in the simplification process we are pursuing, we can tolerate this aberration only to a very limited extent. By stopping down sufficiently, one can attenuate spherical aberration at will, retaining just enough to be useful in certain cases where such a reduction in aperture is acceptable—for example, in landscape photography.
So, scratch spherical aberration off the list as being largely uncontrollable as far as the French were concerned. There is a "however" to this that I'll talk about later, perhaps in a separate post since the topic is rather interesting, but will require more than a few words to work through.
On other optical aberrations ~
Of the other optical imperfections, field curvature (sharpness variation across a flat field), coma (insect shaped highlights off-axis), and field distortion (pincushion, barrel) are mostly of little use in soft focus photography. Only field curvature can be of some interest and then only in portraiture where we might accept increased image diffusion toward the edges of a scene.
On Chromatic Aberration as the preferred optical "softening" agent ~
From Biblioteque de la Revue de Photographie by L. de Pulligny - C. Puyo "Objectifs d'Artiste Practique et Theorie des Objectifs et Teleobjectifs Anachromatique", page 29
Simplification des surfaces sans altération du trait, ce que nous cherchions, l’aberration chromatique tend à nous le donner. C’est donc un agent utile ; c’est, de plus, un agent docile, puisque nous possédons deux moyens simples et surs de régler l’énergie de son action.
In English...
Chromatic aberration tends to provide exactly what we were seeking: a simplification of surfaces without altering the outlines. It is therefore a useful agent; moreover, it is a controllable one, since we possess two simple, reliable ways to regulate the intensity of its effect.
The authors then state that the use of Chromatic Aberration as an optical "softening" agent can help render a photograph in the sfumato style of many Jean-Jacques Henner paintings. This is the painting technique first used by Leonard da Vinci and the effect can be stunningly gorgeous. Just recently I was explaining to someone how I felt how Expressionist/Pictorialist soft focus images in photography can be as sfumato is to painting. Of course I am very pleased to read that the French beat me to this observation by 120+ years!
Miniature Format Lens Selection -
I am interested in applying this as best I can to current materials and processes since I no longer have access to a darkroom, film, nor large format camera/lens gear. I wanted to see if I can somehow duplicate the old Expressionist/Pictorialist soft focus "look" to digital 35mm/Full Frame/APS-C formats.
The first step was to look at lenses. I'd noticed that Wollensak's Velostigmat Series II is an old Tessar formula lens that came with a special feature. It allows for the unscrewing/extending of the first element to introduce and control the level of "softness" in a photograph. This was an important clue as to how I could proceed. If moving the first element of an old lens design did as claimed, then something similar for miniature formats might duplicate the "look."
There are several Cooke Triplet and Zeiss Tessar design lenses that use this focusing technique. To bend first element focusers to the Expressionist/Pictorialist task, the idea is to repurpose the traditional focusing ring to manage "softness." Then, use a separate focusing helicoid to do the actual focusing.
The idea works on 35mm/Full Frame/APS-C digital formats just as anticipated (see: this chart from a prior post on this site).
On Soft Focus Filters -
Relatedly, I spent this summer trying to come to grips with the only soft focus filters I had at the time, which were one each Nikon Nikkor Soft 1 and 2. I used these on both fully corrected lenses as well as a couple first element focuser "softies."
It was a fruitful exercise in learning to view images small. But for viewing at Whole Plate size (on a 10inch tablet, for instance) the images nearly always "fell apart" and appeared to be too soft compared with Expressionist/Pictorlialist works.
What I wanted was a way to gently soften the highlights (to make them "glow") while expanding the blur radius in a way that adhered to the old brass lens Chromatic Aberration French formula.
In a stroke of excellent timing, the Last Great Pictorialist Master pointed friends to the writings and comments of Dave Mullen ASC. A buying spree ensued and the following are my thoughts on filtered introduction of blur and their radii.
- Nikon Nikkor Soft 1 - Frosted glass diffusion. Blur at all apertures with no additional artifacts when stopped down. However, very strong diffusion with blur radii well beyond (2x - 4x) the old heavy crown meniscus Whole Plate optics.
- Zeiss Softar 1 - Micro-lens of variable shape/dimension diffusion pattern. Usable only at wider apertures without showing the "softener" pattern. Strong diffusion with blur radii beyond (1.5x depending on the lens) the old heavy crown meniscus Whole Plate optics.
- Minolta Portrayer 1, 2, 3 - Flat micro-shapes of variable color/dimension diffusion pattern. Interesting filters, these. Need to verify, but I'm thinking the Hoya/Kenko/Hama Softener "A" series may be of similar design. The Minolta filters don't add much blur around the edges, but they do soften broad areas of similar luminosities. If there is a filter that most closely matches sfumato in painting on top of any optical imperfections introduced by a base lens, it would be these.
- Heliopan Duto - Usable only at wider apertures or on longer lenses (85mm - 135mm according to the marketing lit) without showing the "softener" concentric ring pattern. Beautiful blur is possible in the center of the field, with gently increasing "softness" toward the edges.
- Hoya/Kenko Duto - Usable only at wider apertures or on longer lenses (85mm - 135mm according to the marketing lit) without showing the "softener" concentric ring pattern. Beautiful blur is possible in the center of the field, with gently increasing "softness" toward the edges. The "softening" effect is not as strong as the Heliopan.
Expressionist/Pictorialist Blur ~
Remembering the "why" of soft focus lenses...
"... Faire de la Photographie avec art est une chose; faire de l'Art par le moyen de la
Photographie en est, sans doute, une autre... aux définitions diverses de l’oeuvre d’art :
Expression d’un tempérament, — Interprétation de la nature, — Déformation systématique et voulue du réel..."
"... Making a photograph with artistry is one thing. Making art through the medium of photography is, undoubtedly, another... given the various definitions of a work of art: the expression of a temperament—the interpretation of nature—the systematic and deliberate distortion of reality..." [emphasis mine]
From Biblioteque de la Revue de Photographie by L. de Pullignyt - C. Puyo "Objectifs d'Artiste Practique et Theorie des Objectifs et Teleobjectifs Anachromatique"
Using art and drawing as a guide, I think of it this way. When a line is drawn by pencil to paper, the edges of the line are soft and rounded, and are not commonly abrupt and sharp.
One way of making art with photography is to use lenses of varying line softness qualities. This, in the same way an artist uses pencils of differing line weights (#2... #9), line opacity (hard... bold), and edge transition (the width of the line softness).
To verify the level of blur "scales" correctly between old chemical processes and the digital domain I had a close look at old Expressionist/Pictorialist prints and chose images where blur could be more or less accurately measured. The blur radius is 0.60mm to 0.90mm when the image dimensions are 6.5inches x 8.5inches Whole Plate. Thus proving L. de Pulligny et C. Puyo correct.
Now have a look at the sample chart I generated using miniature format lenses and softening filters.
With this I feel the concept of equivalency between old and new is proven and a digital Expressionsit/Pictorialist path forward based on optics and optical effects is possible.
----------- Essential Reading --------------
Dr. Russell Young's thesis paper on soft focus photography
Biblioteque de la Revue de Photographie - L. de Pulligny - C. Puyo "Objectifs d'Artiste Practique et Theorie des Objectifs et Teleobjectifs Anachromatique" - Biblioteque national de France (BnF) (in French)
----------- On Soft Filters --------------
Soft Filters in Cinematography
M. David Mullen, ASC on cinema and photography
----------- Additional Resources ------------
An illustrated guide to early soft focus lenses
Frederick H. Evans was actually a soft focus photographer
History of Dallmeyer optics (on the Dallmeyer 3b in use)
Neo-Pictorialism by Guy Tal
Objectifs de flou artistique (in French)
Wollensak Velostigmat Series II as a first element focuser Expressionist/Pictorialist optic
Tessar design - with scatter plots that show chromatic aberration distributions
No comments:
Post a Comment