Capturing that light and making it into a photograph is the gift of some rather clever scientists of the last centuries. The means of concentration of that light onto the light sensitive material as an image is the mystery of lenses. We photographers have seen a long history of lenses that make sharper and sharper images, with greater contrast, and wider coverage. We have also seen a long list of soft focus (abbreviated sf) lenses, mostly large heavy lenses made for portrait cameras as well as some simple meniscus lenses used for landscapes (Pictorial lenses) . Many of these are in the 12" to 21" focal length, fit on 6" to 10" lens boards and weigh several pounds. In more recent times there have been some smaller lenses in the 6" to 10" focal length and a few special lenses made for 35mm cameras, all with their limitations when used in modern cameras.

How to use them requires an understanding of how they produce their special image characteristics . The image characteristic sf lenses have in common is that they make an image which is not sharp when used at wide apertures. Ordinary good quality commercial lenses, when used at wide apertures, project a sharp plane of focus, and everything in front of, and behind the plane is noticably out of focus.The way in which the out of focus areas appear has come to be known by the Japanese word: "bokeh"

Soft Focus lenses all become sharper as they are closed down to smaller apertures. Most of them are actually quite sharp from about f-11 on (the iris diameter gets smaller ) and as the aperture is closed further,(smaller than the diameter at which maximum sharpness is acheived) the image deteriorates as the aberrations increase, but the image looks more clear because the depth of field increases. All lenses have aberrations as they are closed down, and that includes sharp high quality lenses.

The mystery and the magic of the soft focus lenses is in the quality of the focused image when used between about f-11 and full aperture ( the iris diameter increases).

Soft Focus lenses can be a simple meniscus lenses, like a spectacle lens, a doublet, like the achromat objective lens of a binocular, or two cemented doublets on each side of the aperture (known as a "combination" lens, like a rapid rectilinear, or a triplet like the Cooke lenses. There are other combinations, such as in the Leica Thambar for 35mm.

Many sf lenses just look fuzzy as they are opened up to wide apertures, like the Verito. Also, many inexpensive lenses do this unintentionally when they are trying to be sharp, but this is not the category of lenses we are thinking about as sf lenses. In my opinion, many of the lenses used as soft focus lenses are that way accidentally and not through any particular optical engineering.

The more interesting lenses which feature soft focus look by design are the Kodak Portrait lenses, the Nicola Persheid, and the more complicated Cooke Portrait lenses. The Cooke "knucklers" ( two fingers are used to operate a "brass knuckle" looking handle and move the inner element ), and the Voigtlander Universal Heliars allow variation of the degree of sharpness by movement of a lens element in relation to the others. The softness can be controlled by movement of the mobile element as well as the usual aperture diameter. This allows better control of the d.o.f. with the degree of softness, a useful extra freedom for the photographer who understands how to use it. The real magic of the greatest sf lenses is in how the image looks soft. In addition to the fuzzy image made by many sf lenses is the image which is quite sharp, but covered by a another image which looks airy and luminous.This is the most interesting look in my experience.

The Rodenstock Imagon does a fine job of this by using a disc with multiple holes around a primary hole which serves as the aperture.Fuji sf lenses and some others use this technique in different ways. The limiting side of this method is that the discs are fussy to use, they get lost, fall off, and the apertures are very limiting, especially when using strobe.

The most interesting of the sf lenses for my taste is the Pinkham & Smith series of lenses. They make their magic using aspheric lens elements which project a sharp image within a soft image. It is as if the lens projects two images at the same time, one sharp, one soft, and the combination is very beautiful and very interesting and complex. This technique is different in that most other sf lenses use spherical abberations to soften the image.The downside to the P&S lenses is that they are BIG and heavy, usually made for 8 x 10 cameras or bigger, some for 5 x 7, but very few and they all require studio or packard shutters to be useful and that means "studio" (professional and expensive.)

This is not the lens used for snapshots of a girlfriend at a picnic. So just when the image is dreamy, the equipment is colossal.

This is where the new Cooke PS945 lens has given photographers a new edge. It has the magic of the Pinkham & Smith lens ( the PS is homage to P&S ) , is made to fit a modern shutter ( Copal No 3 ) and fits on a 4" lens board. It can be used on a 4x5 camera easily and synchs with flash. I use mine on a 4x5 Graflex. The lens can also be taken outside into daylight where the Copal 3 has a reasonable set of shutter speeds so that the wider apertures can be used.

Furthermore the lens is color corrected and has beautiful, optically accurate multi coatings. The lens can be used at full aperture, f/4.5, to give a sharp image with a very soft surrounding luminous overlay. The Cooke is much faster than most sf lenses like the Imagon. This gives the speed of the Verito with the complex image of the P&S in a useful shutter. As the aperture is closed down, the soft and the sharp image come together and by about f-11 the image is quite sharp and then it looks more like a regular commercial sharp lens. However it is never really like a sharp lens because even at the small apertures the image is very special because the "bokeh" is not like a commercial lens at all. This lens gives a smooth misty look to the out of focus areas, something the connoisseurs of image quality really like. The Cooke PS 945 becomes a universal lens because it can be used to make portraits of elderly ladies who want to look 30 again and at smaller apertures it is very good for character studies of those who want to relish the warts and hairs of their experience.

The Cooke PS 945 is also an excellent landscape lens because it is sharp enough at small apertures without making the plane of focus pop out from the rest of the image. The out of focus area is beautifully rendered, unlike that of many ordinary sharp lenses and it makes a more integrated image.

This is an exciting development in lens design and manufacture, and a very welcome one.

© Clive Russ, 2002