Photographic filter
Uses of filters in photography
Filters in photography can be classified according to their use:
Clear and ultraviolet
Color correction, also called “color conversion” or “white balance correction”
Color separation, also called Color Subtraction
Contrast enhancement
Infrared
Neutral Density, including the Graduated ND filter and Solar filter
Polarizing
Special Effects of various kinds, including
Graduated color, called color grads
Cross screen and Star diffractors
Diffusion and contrast reduction
Sepia tone
Spot
Close-up or macro diopters, and split diopters or split focus
Clear and ultraviolet
Clear filters, also known as window glass filters or optical flats, are completely transparent, and (ideally) perform no filtering of incoming light at all. The only use of a clear filter is to protect the front of a lens.
UV filters are used to reduce haziness created by ultraviolet light. A UV filter is mostly transparent to visible light, and can be left on the lens for nearly all shots. UV filters are often used for lens protection, much like clear filters. A strong UV filter, such as a Haze-2A or UV17, cuts off some visible light in the violet part of the spectrum, and so has a pale yellow color; these strong filters are more effective at cutting haze, and can reduce purple fringing in digital cameras. Strong UV filters are also sometimes used for warming color photos taken in shade with daylight-type film.
While in certain cases (such as harsh environments) a protection filter may be necessary, there are also downsides to this practice. Arguments for the use of protection filters include:
If the lens is dropped, the filter may well suffer scratches or breakage instead of the front lens element.
One can clean the filter frequently without having to worry about damaging the lens coatings; a filter scratched by cleaning is much less expensive to replace than a lens.
If there is blowing sand the filter may protect the lens from abrasion from sand
Some lenses like Canon’s L series lenses require the use of a filter to complete the weather sealing
And arguments against their use include:
Adding another element degrades image quality due to aberration and flare.
It may reduce the use of lens hoods, since threading a lens hood on top of the clear filter might cause vignetting on some lenses, and since not all clear filters would even have threads allowing a hood to be attached.
If the ring of the filter is struck in a drop it may shatter the filter and cause scratches to the front element rather than a bend in the filter ring of the lens barrel
Additionally, users of UV filters must be careful about the quality of such filters. There is a wide variance in the performance of these filters with respect to their ability to block UV light. Also in lower quality filters, problems with autofocus and image degradation have been noted.[citation needed]
Color correction
A major use is to compensate for the effects of lighting not balanced for the film stock’s rated color temperature (usually 3200 K for professional tungsten lights and 5500 K for daylight): e.g., the 80A blue filter used with daylight film corrects the orange/reddish cast of household tungsten lighting, while the 85B used with tungsten film will correct the bluish cast of daylight. Color correction filters are identified by numbers which sometimes vary from manufacturer to manufacturer. The use of these filters has been greatly reduced by the widespread adoption of digital photography, since color balance problems are now often addressed with software after the image is captured, or with camera settings as the image is captured.
Although the 80A filter is mainly used to correct for the excessive redness of tungsten lighting, it can also be used to oversaturate scenes that already have blue. The photo on the left was shot with a polarizer, while the one on the right was shot with a polarizer and an 80A filter.
Color subtraction
Color subtraction filters work by absorbing certain colors of light, letting the remaining colors through. They can be used to demonstrate the primary colors that make up an image. They are perhaps most frequently used in the printing industry for color separations, and again, use has diminished as digital solutions have become more advanced and abundant.
Contrast enhancement
Filters are commonly used in black and white photography to manipulate contrast. For example a yellow filter will enhance the contrast between clouds and sky by darkening the latter. Orange and red filters will have a stronger effect. A deep green filter will darken the sky too but will lighten green foliage and will make it stand out against the sky. Also see diffusion filters, which are used to reduce contrast.
Effects of using a polarizer and a red filter in black-and-white photography
Polarizer
Main article: Polarizing filter
A polarizing filter, used both in color and black and white photography, filters out light polarized perpendicularly to the axis of the filter. This has two applications in photography: it reduces reflections from some surfaces, and it can darken the sky.
Neutral density
A neutral density filter (ND filter) is a filter of uniform density which attenuates light of all colors equally. It is used to allow a longer exposure (to create blur) or larger aperture (for selective focus) than required for correct exposure in the prevailing light conditions, without changing the tonal balance of the photograph.
A graduated neutral density filter is a neutral density filter with different attenuation at different points, typically clear in one half shading into a higher density in the other. It can be used, for example, to photograph a scene with part in deep shadow and part brightly lit, where otherwise either the shadows would have no detail or the highlights burnt out.
Cross screen
A cross screen filter, also known as a star filter, creates a star pattern, in which lines radiate outward from bright objects. The star pattern is generated by a very fine diffraction grating embedded in the filter, or sometimes by the use of prisms in the filter. The number of stars varies by the construction of the filter, as does the number of points each star has.
Diffusion
An example of a photograph of a person taken using a diffusion filter.
A diffusion filter (also called a softening filter) softens subjects and generates a dreamy haze (see photon diffusion). This is most often used for portraits. It also has the effect of reducing contrast, and the filters are designed, labeled, sold, and used for that purpose too. There are many ways of accomplishing this effect, and thus filters from different manufacturers vary significantly. The two primary approaches are to use some form of grid or netting in the filter, or to use something which is transparent but not optically sharp.
Both effects can be achieved in software, which can in principle provide a very precise degree of control of the level of effect, however the “look” may be noticeably different. If there is too much contrast in a scene, the dynamic range of the digital image sensor or film may be exceeded, which post-processing cannot compensate for, so contrast reduction at the time of image capture may be called for.
Transparent diffusion
Zeiss manufactures a widely noted Softar diffusion filter which is made of many tiny globs of acrylic deposited on one surface which act as microlenses to diffuse the light. In some versions the globs are on the inside of the filter (facing the photographer) while on others they face outwards (towards the subject). In various versions the globs vary in number and diameter, from approximately 97 to 150 globs each 1 mm to 3 mm wide.
Homebrew approaches to transparent diffusion filters are generally based on modifying a clear or UV filter by placing various materials on it; the most popular choices are petroleum jelly, optical cement, and nail polish. Transparent filters are more commonly used for the “dreamy” or “misty” effect than for contrast reduction.
Grid or netting
Various widths, colors (often black or white), and grid shapes (typically diamonds or squares) and spacings of netting, usually made from nylon, are used to provide diffusion effects. These are used both for the “dreamy” look and for contrast reduction. The homebrew approach to this sort of effect is generally to stretch a piece of pantyhose material in front of the lens.
Close-up and split diopter lenses
Main article: Close-up filter
While these are not technically filters but accessory lenses, they are sold by filter manufacturers as part of their product lines, using the same holders and attachment systems. A close-up lens is a single or two-element converging lens used for close-up and macro photography, and works in the same way as spectacles used for reading. The insertion of a converging lens in front of the taking lens reduces the focal length of the combination.
Close-up lenses are usually specified by their optical power, the reciprocal of the focal length in meters. Several close-up lenses may be used in combination; the optical power of the combination is the sum of the optical powers of the component lenses; a set of lenses of +1, +2, and +4 diopters can be combined to provide a range from +1 to +7 in steps of 1.
A split diopter has just a semicircular half of a close-up lens in a normal filter holder. It can be used to photograph a close object and a much more distant background, with everything in sharp focus; with any non-split lens the depth of field would be far too shallow.
Materials and construction
Photo filters are commonly made from glass, resin plastics similar to those used for eyeglasses (such as CR-39), polyester and polycarbonate; sometimes acetate is used. Historically, filters were often made from gelatin, and color gels. While some filters are still described as gelatin or gel filters, they are no longer actually made from gelatin but from one of the plastics mentioned above.
Sometimes the filter is dyed in the mass, in other cases the filter is a thin sheet of material sandwiched between two pieces of clear glass or plastic.
Certain kinds of filters use other materials inside a glass sandwich; for example, polarizers often use various special films, netting filters have nylon netting, and so forth.
The rings on screw-on filters are often made of aluminum, though in more expensive filters brass is used. Aluminum filter rings are much lighter in weight, but can “bind” to the aluminum lens threads they are screwed in to, requiring the use of a filter wrench to get the filter off of the lens. Aluminum also dents or deforms more easily.
High quality filters are multi-coated, with multiple-layer optical coatings to reduce reflections. Uncoated filters can reflect up to 9% of the light, while multi-coated filters can allow for up to 99.7% of the light to pass through; the loss of light is not important, but part of the light is reflected inside the camera, producing flare and reducing the contrast of the image. Manufacturers brand their high-end multi-coated filters with different labels, for example:
Hoya: HMC (Hoya Multi Coating)
B+W: MRC (Multi Resistant Coating)
Filter sizes and mountings
Manufacturers of lenses and filters have standardized on several different sets of sizes over the years.
Threaded round filters
The most common standard filter sizes for circular filters include 30.5 mm, 37 mm, 40.5 mm, 43 mm, 46 mm, 49 mm, 52 mm, 55 mm, 58 mm, 62 mm, 67 mm, 72 mm, 77 mm, 82 mm, 86 mm, 95 mm, 112 mm and 127 mm. Other filter sizes within this range may be hard to find since the filter size may be non-standard or may be rarely used on camera lenses. The specified diameter of the filter in millimeters indicates the diameter of the male threads on the filter housing. The thread pitch is 0.5 mm, 0.75 mm or 1.0 mm, depending on the ring size. A few sizes (e.g. 30.5 mm) come in more than one pitch.
Filter diameter for a particular lens is commonly identified on the lens face by the ligature “”. For example, a lens marking may indicate ” 55mm.”
Square filters
For square filters, 2″ x 2″, 3″ x 3″ and 4″ x 4″ were historically very common and are still made by some manufacturers. 100 mm x 100 mm is very close to 4″x4″, allowing use of many of the same holders, and is one of the more popular sizes currently (2006) in use; it is virtually a standard in the motion picture industry. 75 mm x 75 mm is very close to 3″ x 3″ and while less common today, was much in vogue in the 1990s.
The French manufacturer Cokin makes a wide range of filters and holders in three sizes which is collectively known as the Cokin System. “A” (amateur) size is 67 mm wide, “P” (professional) size is 84 mm wide, and “X Pro” is 130 mm wide. Many other manufacturers make filters to fit Cokin holders. Cokin also makes a filter holder for 100 mm filters, which they call the “Z” size. Most of Cokin’s filters are made of optical resins such as CR-39. A few round filter elements may be attached to the square/rectangular filter holders, usually polarizers and gradient filters which both need to be rotated and are more expensive to manufacture.
Cokin formerly (1980s through mid-1990s) had competition from Hoya’s Hoyarex system (75 mm x 75 mm filters mostly made from resin) and also a range made by Ambico, but both have withdrawn from the market. A small “system” range is still made (as of 2005) by Hitech. In general, square (and sometimes rectangular) filters from one system could be used in another system’s holders if the size was correct, but each made a different system of filter holder which could not be used together. Lee, Tiffen and Singh Ray also make square / rectangular filters in the 100 x 100 and Cokin “P” sizes.
Gel filters are very common in square form, rarely being used in circular form. These are thin flexible sheets of plastic which must be held in rigid frames to prevent them from sagging. Gels are made not only for use as photo filters, but also in a wide range of colors for use in lighting applications, particularly for theatrical lighting. Gel holders are available from all of the square “system” makers, but are additionally provided by many camera manufacturers, by manufacturers of gel filters, and by makers of expensive professional camera accessories (particularly those manufacturers which target the movie and television camera markets.
Square filter systems often have lens shades available to attach to the filter holders.
Rectangular filters
Graduated filters of a given width (100 mm, 67 mm, 84 mm, etc.) are often made oblong, rather than square, in order to allow the position of the gradation to be moved up or down in the picture. This allows, for example, the red part of a sunset filter to be placed at the horizon. These are used with the “system” holders described above.
Bayonet round filters
Certain manufacturers, most notably Rollei and Hasselblad, have created their own systems of bayonet mount for filters. Each design comes in several sizes, such as Bay I through Bay VIII for Rollei, and Bay 50 through Bay 104 for Hasselblad.
Series filters
From the 1930s through to the late 1970s, filters were also made in a sizing system known as a series mount. The filters themselves were round pieces of glass (or occasionally other materials) with no threads or rings attached. Instead, the filter was placed between two rings; the mount ring either screwed into the lens threads or was slipped over the lens barrel and the retaining ring screws into the mounting ring to hold the filter in place. The series designations are generally written as Roman numerals, I to IX, though there are a few sizes not written that way, such as Series 4.5 and Series 5.5.
Series number
filter size
adapter ring
I
II
III
IV
20.6 mm
23.5 mm
4.5
25.5 mm
V
30.2 mm
33.5 mm
5.5
35.9 mm
VI
41.3 mm
44 mm
VII
50.8 mm
54.346 mm, 36 tpi thread pitch
7.5
57.0 mm
VIII
63.5 mm
66.7 mm
8.5/5.5L
74.8 mm x 5.6 mm
8.5/8mm
74.8 mm x 8 mm
IX
82.6 mm
87.5 mm
93
93 mm
103
103 mm
107
107 mm
119
119 mm
125
125 mm
138
138 mm
See also
Color gel
Filter (optics)
List of photographic equipment makers
References
^ Joseph Meehan (1998). The Photographer’s Guide to Using Filters. Watson-Guptill. ISBN 0817454527. http://books.google.com/books?id=RwpgmPAPH60C&pg=PA108&ots=fDXMh8akZ6&dq=haze-2a&as_brr=3&sig=LnBLxKqv4Osg-ZHzLTynKLcZ7Is#PPA107,M1.
^ Tiffen Inc. “Protection & UV Absorbing Filters”. http://www.tiffen.com/Protection_filters.htm.
^ Gary Nugent. “Photoshop Technique: Remove Purple Fringing”. great-landscape-photography.com. http://www.great-landscape-photography.com/remove-purple-fringing.html.
^ Thom Hogan. “Filters by Thom Hogan”. http://www.bythom.com/filters.htm. Retrieved 2007-07-26.
^ Bob Atkins. “UV or not UV?”. http://www.photo.net/equipment/filters/. Retrieved 2007-07-26.
^ Dr. Ching-Kuang Shene. “Coated or Non-Coated?”. http://www.cs.mtu.edu/~shene/DigiCam/User-Guide/filter/filter-coated.html.
External links
Circular Polarizer Filter
Photography Filters
v d e
Photography
Technical terms
Angle of view Aperture Circle of confusion Color temperature Depth of field Depth of focus Exposure Exposure compensation F-number Film format Film speed Focal length Hyperfocal distance Metering mode Perspective distortion Photograph Photographic printing Photographic processes Reciprocity Red-eye effect Science of photography Shutter speed Zone system
Genres
Aerial Black and White Commercial Cloudscape Documentary Erotic Fashion Fine art Forensic Glamour High speed Landscape Nature Nude Photojournalism Pornography Portrait Post-mortem Senior Social documentary Sports Still life Stock Street Vernacular Underwater Wedding Wildlife
Techniques
Afocal photography Bokeh Contre-jour Cross processing Cyanotype Film developing Fill flash Fireworks Harris Shutter Kite aerial Macro Multiple exposure Night Panoramic Panning Photogram (Kirlian) Print toning Rephotography Rollout Sabatier Effect Stereoscopy Stopping Down Sun printing Infrared Ultraviolet Time-lapse Tilt-shift
Composition
Geometry and symmetry Framing Headroom Lead room Rule of thirds Simplicity
Equipment
Camera (Pinhole Rangefinder SLR Still TLR Toy View) Darkroom (Enlarger Safelight) Film (Base Format Holder Stock) Filter Flash Manufacturers Movie projector Photographic lens Slide projector Tripod Zone plate
History
Autochrome Lumire Calotype Daguerreotype Dufaycolor Heliography Timeline of photographic technology
Digital photography
Digital camera (D-SLR Digital back) Photo sharing Digital and film compared Image sensor (CMOS APS CCD Three-CCD Foveon X3) Pixel Film scanner
Color photography
Color Color management (Color space Primary color RGB CMYK) Color film (Print Slide)
Photographic processing
C-41 process Cross processing Developer Dye coupler E-6 process Fixer Push processing Stop bath K-14 process
Other topics
Analog photography Camera obscura Digiscoping Gelatin-silver process Gum printing Holography Lomography Photography and the law Photography museums and galleries (category) Print permanence Vignetting Visual arts
List of photographers List of most expensive photographs Portal WikiProject
Categories: Photography equipment | Optical filtersHidden categories: All articles with unsourced statements | Articles with unsourced statements from October 2009
I am an expert from China Manufacturers, usually analyzes all kind of industries situation, such as battle for volcano island , muslin backdrop.
Processing your request, Please wait....
This is a fantastic article overview! If you are searching for a reliable company to help you learn more about lighting gels , please visit my friends at StageSpot.com. They are the ultimate resource.