Soft focus
In photography, soft focus is a lens flaw, in which the lens forms images that are blurred due to uncorrected spherical aberration. A soft focus lens deliberately introduces spherical aberration which blurs fine texture in the image while retaining sharp edges across areas of high contrast; it is not the same as an out-of-focus image, and the effect cannot be achieved simply by defocusing a sharp lens. Soft focus is also the name of the style of photograph produced by such a lens.
Photography
[edit]Effect
[edit]Soft focus has been described as "an image that is in focus but has a halo of out-of-focus images around it."[1] The first deliberate use of undercorrected spherical aberration, resulting in halos around highlights (also known as "pearly" highlights),[2] is thought to have been by French pictorialists around 1900, spreading to the United States, where these lenses were most popular between 1910 and 1930.[3]: 106 Examples of soft focus lenses include the Petzval portrait lens, Wollensak Veritar, Kodak Portrait, and Rodenstock Imagon.[4]: 27–28
The soft focus effect is used as an effect primarily in glamour photography, because it eliminates blemishes, and in general produces a dream-like image. The effect of a soft focus lens is sometimes approximated by the use of diffusion filter or other method, such as stretching a nylon stocking over the front of the lens, or smearing petroleum jelly on a clear filter or on the front element or even the back element of the lens itself.[5] The latter is less recommended because successive cleaning always introduces a risk to damage the lens's surface.
It can also be approximated with post-processing procedures, either during photographic printing or digital manipulation. Specifically, highlights in an image are blurred, but the bokeh effects of soft focus cannot be reproduced[citation needed].
Special focusing techniques may be required to use a soft focus lens. For example, a front-focusing technique was suggested for the Kodak Portrait, in which the point of focus was placed closer to the camera than the desired location.[2]
Design
[edit]Because soft focus results from what are considered technical flaws, typically spherical and chromatic aberration, many older lenses had soft focus built in as a side effect of their construction. Some lens makers, such as Pinkham-Smith and Busch Nicola Perscheid (see Nicola Perscheid), intentionally designed lenses to take advantage of these flaws and, as color became available, chromatic aberration was less desirable, but well-managed spherical aberration was desirable.
Newer lenses are optimized to minimize optical aberrations, but there are contemporary lenses which are designed to have adjustable levels of spherical aberration at wide apertures. The effect can be disabled entirely as well, in which case the lens is sharp. These lenses include the Minolta Varisoft Rokkor 85mm f/2.8, Canon EF 135mm lens f/2.8 with Softfocus, Pentax SMC 28mm f2.8 FA Soft Lens, Mamiya 180mm f/4.0 Soft Focus Lens for 645 Cameras, and the Lensbaby Velvet 56mm lens.
This class of soft-focus lenses should be considered distinct from lenses designed to render pleasant bokeh using an apodization filter, such as the Minolta STF 135mm f/2.8 [T4.5].
Thambar
[edit]
In the mid-1930s, Leitz designed a legendary soft-focus lens, the Thambar 90mm f2.2, for the Leica rangefinder cameras. It was made in small numbers, no more than 3000 units. It is a rare collector's item today.[6] In 2017, a new version was produced, costing $6,495. A lens from the original series can fetch between $3,000 and $8,000, depending on condition.[7]
See also
[edit]- Rodenstock Imagon
- Seibold's Dreamagon
- Aberration in optical systems
- Lens (optics)
- Special effect
- Bokeh
- Convolution
- Depth of field
- Low-pass filter
- Gaussian blur
References
[edit]- ^ The visual dictionary of photography. AVA Publishing. 2010. p. 232. ISBN 978-2-940411-04-7.
- ^ a b "Kodak Portrait Lens 305mm (12-in.) f/4.8" (PDF). Eastman Kodak Company. 1952. Retrieved 2024-07-29.
- ^ Neblette, C. B.; Murray, Allen E. (1973). Photographic lenses (Revised ed.). Dobbs Ferry, New York: Morgan & Morgan, Inc. ISBN 0-87100-070-9. LCCN 64-20637. Retrieved 2024-07-29.
- ^ Neblette, C. B. (1959). Photographic lens manual and directory (First ed.). New York, New York: Morgan & Morgan, Inc. LCCN 59-11726. Retrieved 2024-07-29.
- ^ Bernstein, Gary (1985). Pro techniques of beauty & glamour photography. HPBooks. p. 7. ISBN 0-89586-364-2. LCCN 85-60457. Retrieved 2024-07-29.
An image can be softened with the use of a good diffusion attachment. In my beauty and glamour photography, the subject or client frequently prefers a soft-focus version. The diffusion can take place when the camera exposure is made, or later. ... I've achieved wonderful results with diffusers I made myself. As base, I use glass ultraviolet (UV) filters or sheets of acetate. On this base I spray commercial fixative in varying densities, depending on the degree of softening I want.
- ^ Hicks, Roger W. (2005-04-01). "The Leitz Thambar 90 mm f/2.2: Why Is It Considered A Legendary Portrait Lens?". Shutterbug.
- ^ Overgaard, Thorsten. "Technical data on the Leitz Thambar f/2.2".
External links
[edit]
- Soft Focus Lens Article
- Soft-Focus Lenses and Techniques, an overview for large format photographers