Soft focus

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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

Effect

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]Template:Rp Noted practitioners of soft focus photography include Julia Margaret Cameron,[4] Bob Guccione,[5] and early Edward Weston, though Weston was later credited with moving photography away from soft focus pictorialism.[6][7]

The soft focus effect is used primarily in glamour photography, because it eliminates blemishes. In general, soft focus photography produces a misty, dream-like image, sometimes characterized as romantic.[8]

Technique

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 actual subject.[2] Unlike typical camera lenses, which have a generally symmetric depth of field characteristic extending both in front of and behind the point of focus, the uncorrected spherical aberration results in a depth of field which extends past (behind) the point of focus, but not in front.[9]

Physically, the effect of a soft focus lens may be 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.[10] 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 through digital manipulation. Specifically, highlights in an image are blurred, but the bokeh effects of soft focus cannot be reproducedScript error: No such module "Unsubst"..

Design

File:Appareil photo Vest Pocket Autographic Kodak 06.jpg
Vest Pocket Kodak with 2-element meniscus lens and integral hood

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. For example, the two-element cemented meniscus lens fitted to early Vest Pocket Kodak cameras had a dish-shaped hood[11] which controlled spherical aberration by reducing the effective aperture to <templatestyles src="F//styles.css" />f/11; when the hood is removed, the resulting uncorrected images have a strong soft focus effect. After this modification, the lens enjoyed significant popularity in Japan during the 1970s, remounted to modern cameras.[12][13] Photographers called this lens the Script error: No such module "Nihongo"., referring to the camera's name and single-group lens construction,[14] and the technique was championed by several Japanese photographers, including Shōji Ueda.[15] The basic design of this lens was revived in 2016 as the Yasuhara MOMO 100.[16]

Some lenses designed and sold during the heyday of soft focus lenses (Template:Circa), including the Pinkham & Smith Visual Quality series[17][18] and Busch Nicola Perscheid,[19] were designed intentionally to take advantage of these flaws. As color films became available, well-managed spherical aberration became more desirable than chromatic aberration.

File:US4124276A (Okano Nakamura & Ogura, 1975).svg
Maximum (top) and minimum (bottom) spherical aberration configurations in a modern soft focus lens.[20]

Newer lenses are optimized to minimize optical aberrations, but starting from the 1970s, manufacturers began releasing specialized contemporary lenses which are designed with adjustable levels of spherical aberration at wide apertures. The effect can be disabled entirely as well, in which case the lens is sharp.[21] These modern soft focus lenses and their effect on the images should be considered distinct from the effect of lenses designed to render smooth Template:Transliteration using an apodization filter, such as the [[Minolta STF 135mm f/2.8 T4.5|Minolta STF 135mm <templatestyles src="F//styles.css" />f/2.8 Template:!(T4.5Template:)!]].[22]

As described in U.S. Patent 4,124,276,[20] realized as the Minolta Varisoft Rokkor,[23]Template:Rp a modern example with variable spherical aberration is a six-element, five-group lens which can be divided into three composite lens groups, marked A-I, A-II, and B. The first four elements (A-I, closest to the object being photographed) are moved as a unit to focus the lens, increasing the meniscus-shaped air gap between A-I and A-II as the lens is focused closer. The air gap distance between A-II and B is used to control spherical aberration; spherical aberration increases as the distance between A-II and B grows.[20] In the patent summary, the inventors noted the object side lens group (A-I) was a Tessar design, although they added that any suitable lens would do, such as a Cooke triplet or Double Gauss lens; the preferred embodiment uses two meniscus lenses on the image side to control spherical aberration.[20]

File:BennyTrapp Imagon.jpg
Imagon fitted with <templatestyles src="F//styles.css" />f/7.7-equivalent sieve aperture.

As an alternative to variable element spacing, some soft focus lenses such as the Rodenstock Imagon use interchangeable sieve aperture "grid" or "diffusion" discs which have a perforated annular shape to control the balance of light recorded between the relatively well-corrected center of the lens and the uncorrected periphery. As light from the periphery is restricted, the soft focus effect becomes less pronounced. Effective aperture values (for computing exposure) range from <templatestyles src="F//styles.css" />f/5.8 to <templatestyles src="F//styles.css" />f/11.5.[24][25]

Examples

Some examples of soft focus lenses, including modern (after 1950) lenses with controllable amounts of spherical aberration, include:[26]Template:Rp

Selected soft focus lenses
colspan=3 Template:Diagonal split header FL (mm) Ap. Intro. Min. focus Const. Dimensions MethodTemplate:Efn Notes / Refs.
Mfr. Name Mount(s) Ele Grp Φ×L Wgt. Filter (mm)
Canon New FD 85mm <templatestyles src="F//styles.css" />f/2.8 Soft Focus FD 85 <templatestyles src="F//styles.css" />f/2.8–22 1983 Template:Cvt 6 4 Template:Cvt Template:Cvt 58 V Sliding soft focus control[21][27]
Canon EF 135mm <templatestyles src="F//styles.css" />f/2.8 Soft Focus EF 135 <templatestyles src="F//styles.css" />f/2.8–32 1987 Template:Cvt 7 6 Template:Cvt Template:Cvt 52 V [28][29]
Fujifilm EBC Fujinon-SF 85mm <templatestyles src="F//styles.css" />f/4 M42 85 <templatestyles src="F//styles.css" />f/4–16 Template:Circa Template:Cvt 4 4 Template:Cvt Template:Cvt 49 CS [30]
Fujifilm GX(M) SF 190mm <templatestyles src="F//styles.css" />f/8.0 GX680 190 <templatestyles src="F//styles.css" />f/8–64 1988 Template:Cvt 3 3 Template:Cvt Template:Cvt 82 CS Discontinued 2011[31][32]
Fujifilm Fujinon-SF #1 180 <templatestyles src="F//styles.css" />f/5.6–22 ? varies 3 3 Template:Cvt Template:Cvt 46 CS [33][34]
#2/#3 250 Template:Cvt Template:Cvt 67
barrel 420 Template:Cvt Template:Cvt 82
Kenko MC Soft 35mm F:4 T2 35 <templatestyles src="F//styles.css" />f/4–22 ? Template:Cvt ? ? ? ? 52 C
Kenko べスタンSoft 45mm F:4.5 "P"Template:Efn 45 <templatestyles src="F//styles.css" />f/4.5–22 1995 Template:Cvt 2 1 Template:Cvt Template:Cvt 52 C [35][36]
Kenko MC Soft 85mm F:2.5 "P"Template:Efn 85 <templatestyles src="F//styles.css" />f/2.5–8 1987 Template:Cvt 3 3 Template:Cvt Template:Cvt 52 C [37][38]
Template:Ill Kiyohara Soft VK50R (multiple)Template:Efn 50 <templatestyles src="F//styles.css" />f/4.5–16 1987 Template:Cvt 2 1 ? Template:Cvt 40.5 C Designed by Takano Eiichi.[39][40]
Template:Ill Kiyohara Soft VK70R (multiple)Template:Efn 70 <templatestyles src="F//styles.css" />f/5–11 1986 Template:Cvt 2 1 Template:Cvt Template:Cvt 49 C Designed by Eiichi Sakurai.[41][42]
Lensbaby Soft Focus Optic (multiple)Template:Efn 50 <templatestyles src="F//styles.css" />f/2–22 2009 Template:Cvt 2 1 Template:Cvt ? Template:N/A S 3 magnetic sieve aperture discs, <templatestyles src="F//styles.css" />f/3.3 and <templatestyles src="F//styles.css" />f/4.8 overall.[43][44][45]
Lensbaby Soft Focus II (multiple)Template:Efn 50 <templatestyles src="F//styles.css" />f/2.5–22 2022 Template:Cvt 2 1 ? ? 46 CS Internal diaphragm + magnetic sieve apertures[46][47]
Minolta Varisoft Rokkor 85mm <templatestyles src="F//styles.css" />f/2.8 SR/ MC/ MD 85 <templatestyles src="F//styles.css" />f/2.8–16 1978 Template:Cvt 6 5 Template:Cvt Template:Cvt 55 V [48][49]
Nikon Script error: No such module "Nihongo". NF 90 <templatestyles src="F//styles.css" />f/4.8 1995 Template:Cvt 2 1 Template:Cvt Template:Cvt 52 W Included in Amusing Lenses (1995) / Fun Fun LensSet (2000)[50][51][52]
Rodenstock Imagon #3 (typ. Φ=65.3 mm) 200 H 5.8–11.5 1926 varies 2 1 Template:Cvt Template:Cvt 55 (slip-on) S Most commonly found in 200, 250, or 300mm, but 170, 360, 420, and 480mm exist.[53][24][25]Template:Rp[54][55]
250 Template:Cvt Template:Cvt
#3 or #4 300 Template:Cvt Template:Cvt 55 or 78 (slip-on)
Notes

Template:Notelist Template:Div col

  • Kodak Portrait (4×5+)[2]
  • Leica Thambar 90mm <templatestyles src="F//styles.css" />f/2.2 (M39)[56]
  • Lensbaby Velvet 28 <templatestyles src="F//styles.css" />f/2.5, 56mm <templatestyles src="F//styles.css" />f/1.6, 85mm <templatestyles src="F//styles.css" />f/1.8, and Trio 28 (multiple dSLR and mirrorless camera systems)[57]
  • Mamiya-Sekor SF C 145mm <templatestyles src="F//styles.css" />f/4.0 (M645)[58]
  • Mamiya-Sekor SF C 150mm <templatestyles src="F//styles.css" />f/4.0 (RB67)[59]
  • Mamiya Soft M 180mm <templatestyles src="F//styles.css" />f/4.0 D/L Variable Soft Focus (RZ67)[60]
  • Minolta AF 100mm <templatestyles src="F//styles.css" />f/2.8 (A/α)[61]
  • SMC Pentax-FA 28mm <templatestyles src="F//styles.css" />f/2.8 SOFT (PK)[62]
  • SMC Pentax Soft 85mm <templatestyles src="F//styles.css" />f/2.2 (PK)[63]
  • SMC Pentax-F 85mm <templatestyles src="F//styles.css" />f/2.8 SOFT (PK)[64][65]
  • SMC Pentax-FA 85mm <templatestyles src="F//styles.css" />f/2.8 SOFT (PK)[66]
  • SMC Pentax 67 Soft 120mm <templatestyles src="F//styles.css" />f/3.5 (P67)[67]
  • Petzval portrait (4×5+)
  • Seibold Dreamagon 90mm <templatestyles src="F//styles.css" />f/4
  • Sima Soft Focus 100mm <templatestyles src="F//styles.css" />f/2 (T)[68]
  • Spiratone Portragon 100mm <templatestyles src="F//styles.css" />f/4 (T)[69]
  • Tamron SP 70–150mm <templatestyles src="F//styles.css" />f/2.8 Soft (Adaptall-2)[70]
  • Wollensak Veritar (4×5+)[71]
  • Yasuhara Momo 100 43mm <templatestyles src="F//styles.css" />f/6.4 (multiple dSLR and mirrorless camera systems)[72][73]

Template:Div col end

Thambar

Template:Multiple image In 1935, Leitz released a legendary soft-focus lens, the Thambar 90mm <templatestyles src="F//styles.css" />f/2.2, for the Leica rangefinder cameras. It was supplied with a special filter to block light through the center of the lens, resulting in the image being formed by relatively uncorrected aberrations through the periphery.[56]

It was made in small numbers, no more than 3000 units, and is a rare collector's item today.[74] 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.[75]

See also

References

Template:Reflist

External links

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de:Weichzeichnung

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