Soft focus
Encyclopedia
In photography
, soft focus is a lens
flaw, in which the lens forms images that are blurred due to spherical aberration
. A soft focus lens deliberately introduces spherical aberration in order to give the appearance of blurring the image while retaining sharp edges; 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.
Because soft focus is a technical flaw, many older lenses
had soft focus built in as a side effect of their construction. Newer lenses are optimized to minimize optical aberrations, but there are lenses such as the Canon EF 135mm lens
f/2.8 with Softfocus and Pentax
SMC
28mm f2.8 FA Soft Lens, to name but two, which have adjustable levels of spherical aberration at wide apertures. The effect can be disabled entirely as well, in which case the lens is sharp.
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.
Nikon produces a series of DC ("Defocus Control") lenses which are sometimes confused with the soft focus effect, but these are not soft focus lenses, as they do not introduce spherical aberration over the whole field.
The soft focus effect is used as an effect for glamour photography
, because the effect 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 of the lens itself.
It can also be approximated with post-processing
procedures. Specifically, highlights in an image are blurred.
Photography
Photography is the art, science and practice of creating durable images by recording light or other electromagnetic radiation, either electronically by means of an image sensor or chemically by means of a light-sensitive material such as photographic film...
, soft focus is a lens
Lens (optics)
A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
flaw, in which the lens forms images that are blurred due to spherical aberration
Spherical aberration
thumb|right|Spherical aberration. A perfect lens focuses all incoming rays to a point on the [[Optical axis|optic axis]]. A real lens with spherical surfaces suffers from spherical aberration: it focuses rays more tightly if they enter it far from the optic axis than if they enter closer to the...
. A soft focus lens deliberately introduces spherical aberration in order to give the appearance of blurring the image while retaining sharp edges; it is not the same as an out-of-focus
Focus (optics)
In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...
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
Photographic lens
A camera lens is an optical lens or assembly of lenses used in conjunction with a camera body and mechanism to make images of objects either on photographic film or on other media capable of storing an image chemically or electronically.While in principle a simple convex lens will suffice, in...
had soft focus built in as a side effect of their construction. Newer lenses are optimized to minimize optical aberrations, but there are lenses such as the Canon EF 135mm lens
Canon EF 135mm lens
-EF 135mm 2L USM:The Canon EF 135mm 2L USM is a short-to-medium telephoto lens. The "135/2" is mainly used for portrait photography and for indoor sports, where the lighting is often poor. The fast aperture makes the lens ideal for both of these applications....
f/2.8 with Softfocus and Pentax
Pentax
Pentax is a brand name used by Hoya Corporation for its medical-related products & services and Pentax Ricoh Imaging Company for cameras, sport optics , etc. Hoya purchased and merged with the Japanese optics company on March 31, 2008. Hoya's Pentax imaging business was sold to Ricoh Company, Ltd...
SMC
SMC
-Technology:* Secure multiparty computation, a cryptography problem* Secure Managed Client, a centrally managed discless solution for PCs* SMC connector, used in radio-frequency circuits* Sliding mode control* Self-modifying code* SmartMedia Card...
28mm f2.8 FA Soft Lens, to name but two, which have adjustable levels of spherical aberration at wide apertures. The effect can be disabled entirely as well, in which case the lens is sharp.
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.
Nikon produces a series of DC ("Defocus Control") lenses which are sometimes confused with the soft focus effect, but these are not soft focus lenses, as they do not introduce spherical aberration over the whole field.
The soft focus effect is used as an effect for glamour photography
Glamour photography
Glamour photography is a genre of photography whereby the subjects, usually female, are portrayed in a romantic or sexually alluring way. The subjects may be fully clothed or seminude, but glamour photography stops short of deliberately arousing the viewer and being pornographic photography.Glamour...
, because the effect 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
Diffusion filter
A diffusion filter is a translucent photographic filter used for a special effect. When used in front of the camera lens, a diffusion filter softens subjects and generates a dreamy haze. This can also be improvised by smearing petroleum jelly on a UV filter or shooting through a nylon stocking...
or other method, such as stretching a nylon stocking over the front of the lens, or smearing petroleum jelly
Petroleum jelly
Petroleum jelly, petrolatum, white petrolatum or soft paraffin, CAS number 8009-03-8, is a semi-solid mixture of hydrocarbons , originally promoted as a topical ointment for its healing properties...
on a clear filter or on the front element of the lens itself.
It can also be approximated with post-processing
Image processing
In electrical engineering and computer science, image processing is any form of signal processing for which the input is an image, such as a photograph or video frame; the output of image processing may be either an image or, a set of characteristics or parameters related to the image...
procedures. Specifically, highlights in an image are blurred.
See also
- Aberration in optical systemsAberration in optical systemsAberrations are departures of the performance of an optical system from the predictions of paraxial optics. Aberration leads to blurring of the image produced by an image-forming optical system. It occurs when light from one point of an object after transmission through the system does not converge...
- Lens (optics)Lens (optics)A lens is an optical device with perfect or approximate axial symmetry which transmits and refracts light, converging or diverging the beam. A simple lens consists of a single optical element...
- Special effectSpecial effectThe illusions used in the film, television, theatre, or entertainment industries to simulate the imagined events in a story are traditionally called special effects ....
- BokehBokehIn photography, bokeh is the blur, or the aesthetic quality of the blur, in out-of-focus areas of an image, or "the way the lens renders out-of-focus points of light."...
- ConvolutionConvolutionIn mathematics and, in particular, functional analysis, convolution is a mathematical operation on two functions f and g, producing a third function that is typically viewed as a modified version of one of the original functions. Convolution is similar to cross-correlation...
- low-pass filterLow-pass filterA low-pass filter is an electronic filter that passes low-frequency signals but attenuates signals with frequencies higher than the cutoff frequency. The actual amount of attenuation for each frequency varies from filter to filter. It is sometimes called a high-cut filter, or treble cut filter...
External links
- Soft Focus Lens Article
- Soft-Focus Lenses and Techniques, an overview for large formatLarge formatLarge format refers to any imaging format of 4×5 inches or larger. Large format is larger than "medium format", the 6×6 cm or 6×9 cm size of Hasselblad, Rollei, Kowa, Pentax etc cameras , and much larger than the 24×36 mm frame of 35 mm format.The main advantage...
photographers - Article on creating the soft-focus effect in Photoshop.
- Article on creating the soft-focus effect in Gimp.