Contemporary soft-focus work

[Jason Greenberg Motamedi]

I should qualify my statement above by noting that there is a Petzval variant, the Dallmeyer Patent Portrait (which became the Wolly Vitax once Dallmeyer's patent was up) that allows for a diffused focus by adjusting the spacing between the rear elements.

While this was often advertised in the 20th century as a "soft focus" adjustment, I believe its original purpose was to extend or diffuse the focus by the purposeful addition of spherical aberration. In other words, by increasing the spacing between elements the photographer could sacrifice sharpness for an increased depth of field.

[Ernest Purdum]

Mark, when you speak of different wavelengths you are talking about chromatic aberration which, though intentionally present in some early soft focus lenses, is a problem with panchromatic, let alone color, films. Much more commonly, spherical aberration is used to produce the softened effect. The designer can just leave enough spherical aberration in so that images made at large apertures will be quite soft, or he can induce the aberration by arranging for element separation. The latter approach has been used with both Petzval and anastigmat lenses.Some of the anastigmats were quite versatile since they could be as sharp as other lenses of their period, yet soft when desired without necessarily using large apertures. Good examples are several Cooke types and the Graf "Variable". The name of the Graf lens came from the fact that changing element separation resulted in focal length variation.

[Ted Harris]

Mark, actually we are down to 2 + 1 manufacturers. The Rodenstock Imagons were discontinued about a year or a bit more ago although there are a scattered few available new on the odd dealer's shelf. For example, I found a new on at Calumet in Boston about 6 months ago. I say 2 + 1 because I am not sure I am comfortable including Congo as a 'high end' manufacturer. largely because of the seeming variability of their quality control.

[William Mortensen]

Right you are, Ernest! I was thinking of very early soft focus lenses which, though rarer, I'm more familiar with. Spherical aberration produces a similar, but much more predictable effect achromatically.

Another good example of a soft focus lens that can be adjusted by unscrewing the *front* element is certain Wollensak Velostigmats. I think these are the most common soft focus lenses out there, often priced quite low. Many people have them and don't realize what they are.