(Redirected from Anamorphic 2.39)
Director: William Bradley Cinematographer: Thomas Ackerman ASC 2nd Unit Directors: Gregory McClatchy, Dario Cioni Film Editor: William Hoy ACE Camera: Panaflex Platinum (35mm) Lenses: Primo (Anamorphic) AR: 2.35:1. Digital Anamorphic (2K)(2.8K)(4K): Filmed with the Alexa Mini, Alexa SXT, BlackMagic Cinema, Canon EOS 5D Mark III, Red Monstro and Sony CineAlta Venice equipped with Panavision Primo Anamorphic & Spherical, G-Series Anamorphic, T-Series Anamorphic, ATZ and Leica Summilux-C Lenses, shot by Robrecht Heyvaert. Widescreen really starts at 2.35:1 and 2.39:1 with moderate anamorphic lenses, and 2.66:1 provides a really long and thin widescreen format. In film-based cinema, the ends of a wide format might be cropped from the picture to meet the 2.39:1 requirement, especially when a 2x anamorphic lens is in use, but in digital video, a timeline of any. Anamorphic definition is - producing, relating to, or marked by intentional distortion (as by unequal magnification along perpendicular axes) of an image. How to use anamorphic in a sentence.
Figure 1. Shooting without an anamorphic lens, in widescreen picture format on 4-perf film; some of the film surface area is wasted on the upper/lower, black frame lines.
Figure 2. Shooting with an anamorphic lens stretches the image vertically to cover the entire film frame, resulting in a higher quality but distorted image. When projecting the film, a reverse, complementary lens (of the same anamorphic power) shrinks the image vertically to the original proportions.
Anamorphic format is the cinematography technique of shooting a widescreen picture on standard 35 mm film or other visual recording media with a non-widescreen native aspect ratio. It also refers to the projection format in which a distorted image is 'stretched' by an anamorphic projection lens to recreate the original aspect ratio on the viewing screen. (It should not be confused with anamorphic widescreen, a different video encoding concept that uses similar principles but different means.) The word anamorphic and its derivatives stem from the Greek anamorphoun ('to transform'),[1] compound of morphé ('form, shape')[2] with the prefix aná ('back, against').[3] In the late 1990s and 2000s, anamorphic lost popularity in comparison to 'flat' (or 'spherical') formats such as Super 35 with the advent of digital intermediates; however in the years since digital cinema cameras and projectors have become commonplace, anamorphic has experienced a considerable resurgence of popularity, due in large part to the higher base ISO sensitivity of digital sensors, which facilitates shooting at smaller apertures.
History[edit]
The process of anamorphosing optics was developed by Henri Chrétien during World War I to provide a wide angle viewer for military tanks. The optical process was called Hypergonar by Chrétien and was capable of showing a field of view of 180 degrees. After the war, the technology was first used in a cinematic context in the short film Construire un Feu (To Build a Fire, based on the 1908 Jack London story of the same name) in 1927 by Claude Autant-Lara.[4]
In the 1920s, phonograph and motion picture pioneer Leon F. Douglass also created special effects and anamorphic widescreen motion picture cameras. However, how this relates to the earlier French invention, and later development, is unclear.[5]
Anamorphic widescreen was not used again for cinematography until 1952 when Twentieth Century-Fox bought the rights to the technique to create its CinemaScope widescreen technique.[4] CinemaScope was one of many widescreen formats developed in the 1950s to compete with the popularity of television and bring audiences back to the cinemas. The Robe, which premiered in 1953, was the first feature film released that was filmed with an anamorphic lens.
Development[edit]
The introduction of anamorphic widescreen arose from a desire for wider aspect ratios that maximised overall image detail while retaining the use of standard (4 perf per frame) cameras and projectors. The modern anamorphic format has an aspect ratio of 2.39:1, meaning the (projected) picture's width is 2.39 times its height, (this is sometimes approximated to 2.4:1). The older Academy format35 mm film (standard non-anamorphic full frame with sound tracks in the image area) has an aspect ratio of 1.375:1, which, when projected, is not as wide.
Anamorphic widescreen was a response to a shortcoming in the non-anamorphic spherical (a.k.a. 'flat') widescreen format. With a non-anamorphic lens, the picture is recorded onto the film negative such that its full width fits within the film's frame, but not its full height. A substantial part of the frame area is thereby wasted, being occupied (on the negative) by a portion of the image which is subsequently matted-out (i.e. masked, either on the print or in the projector) and so not projected, in order to create the widescreen image.
To increase overall image detail, by using all the available area of the negative for only that portion of the image which will be projected, an anamorphic lens is used during photography to compress the image horizontally, thereby filling the full (4 perf) frame's area with the portion of the image that corresponds to the area projected in the non-anamorphic format. Up to the early 1960s, three major methods of anamorphosing the image were used: counter-rotated prisms (e.g. Ultra Panavision),[6] curved mirrors in combination with the principle of Total Internal Reflection (e.g. Technirama),[7] and cylindrical lenses (lenses curved, hence squeezing the image being photographed, in only one direction, as with a cylinder, e.g. the original CinemaScope system based on Henri Chrétien's design).[8] Regardless of method, the anamorphic lens projects a horizontally squeezed image on the film negative. This deliberate geometric distortion is then reversed on projection, resulting in a wider aspect ratio on-screen than that of the negative's frame.
Equipment[edit]
An anamorphic lens consists of a regular spherical lens, plus an anamorphic attachment (or an integrated lens element) that does the anamorphosing. The anamorphic element operates at infinite focal length, so that it has little or no effect on the focus of the primary lens it's mounted on but still anamorphoses (distorts) the optical field. A cameraman using an anamorphic attachment uses a spherical lens of a different focal length than they would use for Academy format (i.e. one sufficient to produce an image the full height of the frame and twice its width), and the anamorphic attachment squeezes the image (in the horizontal plane only) to half-width. Other anamorphic attachments existed (that were relatively rarely used) which would expand the image in the vertical dimension (e.g. in the early Technirama system mentioned above), so that (in the case of the common 2-times anamorphic lens) a frame twice as high as it might have been filled the available film area. In either case, since a larger film area recorded the same picture the image quality was improved.
The distortion (horizontal compression) introduced in the camera must be corrected when the film is projected, so another lens is used in the projection booth that restores the picture back to its correct proportions (or, in the case of the now obsolete Technirama system, squeezes the image vertically) to restore normal geometry. The picture is not manipulated in any way in the dimension that is perpendicular to the one anamorphosed.
It may seem that it would be easier to simply use a wider film for recording movies. However, since 35 mm film was already in widespread use, it was more economically feasible for film producers and exhibitors to simply attach a special lens to the camera or projector, rather than invest in an entirely new film format, which would require new cameras, projectors, editing equipment and so forth.
Naming[edit]
Cinerama was an earlier attempt to solve the problem of high-quality widescreen imaging, but anamorphic widescreen eventually proved more practical. Cinerama (which had an aspect ratio of 2.59:1) consisted of three simultaneously projected images side-by-side on the same screen. However, in practice the images never blended together perfectly at the edges. The system also suffered from various technical drawbacks, in that it required three projectors, a 6-perf-high frame, four times as much film, and three cameras (eventually simplified to just one camera with three lenses and three streaming reels of film and the attendant machinery), plus a host of synchronization problems. Nonetheless, the format was popular enough with audiences to trigger off the widescreen developments of the early 1950s. A few films were distributed in Cinerama format and shown in special theaters, but anamorphic widescreen was more attractive to the Studios since it could realize a similar aspect ratio and without the disadvantages of Cinerama's complexities and costs.
The anamorphic widescreen format in use today is commonly called 'Scope' (a contraction of the early term CinemaScope), or 2.35:1 (the latter being a misnomer born of old habit; see 'Aspect ratio' section below). Filmed in Panavision is a phrase contractually required for films shot using Panavision's anamorphic lenses. All of these phrases mean the same thing: the final print uses a 2:1 anamorphic projector lens that expands the image by exactly twice the amount horizontally as vertically. This format is essentially the same as that of CinemaScope, except for some technical developments, such as the ability to shoot closeups without any facial distortion. (CinemaScope films seldom used full facial closeups, because of a condition known as CinemaScope mumps, which distorted faces as they got closer to the camera.)
Anamorphic 2 2 Player Games
Optical characteristics[edit]
Example of blue-line horizontal anamorphic flare
There are artifacts that can occur when using an anamorphic camera lens that do not occur when using an ordinary spherical lens. One is a kind of lens flare that has a long horizontal line, usually with a blue tint, and is most often visible when there is a bright light in the frame, such as from car headlights, in an otherwise dark scene. This artifact is not always considered a problem., and even has become associated with a certain cinematic look, and often emulated using a special effect filter in scenes shot with a non-anamorphic lens. Another common aspect of anamorphic lenses is that light reflections within the lens are elliptical, rather than round as in ordinary cinematography. Additionally, wide angle anamorphic lenses of less than 40 mm focal length produce a cylindrical perspective, which some directors and cinematographers, particularly Wes Anderson, use as a stylistic trademark.
Many wide-angle anamorphic lenses render a cylindrical perspective, as simulated by this stitched panorama of Cavendish House, Leicester. Contrast the straight vertical plane with the curved horizontal plane.
Another characteristic of anamorphic lenses, because they stretch the image vertically, is that out-of-focus elements tend to blur more in the vertical direction. An out-of-focus point of light in the background (called bokeh[9]) appear as a vertical oval rather than as a circle. When the camera shifts focus, there is often a noticeable effect whereby objects appear to stretch vertically when going out of focus. However, the commonly cited claim that anamorphic lenses produce a shallower depth of field is not entirely true. Because of the cylindrical element in the lens, anamorphic lenses take in a horizontal angle of view twice as wide as a spherical lens of the same focal length. Because of this, cinematographers often use a 50 mm anamorphic lens when they would otherwise use a 25 mm spherical lens, or a 70 mm rather than a 35 mm, and so on.
A third characteristic, particularly of simple anamorphic add-on attachments, is 'anamorphic mumps'. For reasons of practical optics, the anamorphic squeeze is not uniform across the image field in any anamorphic system (whether cylindrical, prismatic or mirror-based). This variation results in some areas of the film image appearing more stretched than others. In the case of an actor's face, when positioned in the center of the screen faces look somewhat like they have the mumps, hence the name for the phenomenon. Conversely, at the edges of the screen actors in full-length view can become skinny-looking. In medium shots, if the actor walks across the screen from one side to the other, he will increase in apparent girth. Early CinemaScope presentations in particular (using Chrétien's off-the-shelf lenses) suffered from this. Panavision was the first company to produce an anti-mumps system in the late 1950s.
Panavision used a second lens (i.e. an add-on adapter) which was mechanically linked to the focus position of the primary lens. This changed the anamorphic ratio as the focus changed, resulting in the area of interest on-screen having a normal-looking geometry. Later cylindrical lens systems used, instead, two sets of anamorphic optics: one was a more robust 'squeeze' system, which was coupled with a slight expansion sub-system. The expansion sub-system was counter-rotated in relation to the main squeeze system, all in mechanical interlinkage with the focus mechanism of the primary lens: this combination changed the anamorphic ratio and minimized the effect of anamorphic mumps in the area of interest in the frame. Although these techniques were regarded as a fix for anamorphic mumps, they were actually only a compromise. Cinematographers still had to frame scenes carefully to avoid the recognizable side-effects of the change in aspect ratio.
Recent use[edit]
Although the anamorphic widescreen format is still in use as a camera format, it has been losing popularity in favour of flat formats, mainly Super 35. (In Super 35, the film is shot flat, then matted, and optically printed as an anamorphic release print.) The decline in popularity can be attributed to the artifacts, distortions, speed, and expenses (in comparison to its spherical counterpart).
An anamorphic lens is often slower (has a smaller effective aperture) than a similar spherical lens, and thus requires more light and makes shooting low-light scenes more difficult. The anamorphic-scope camera format does not preserve any of the image above or below the frame, so it may not transfer as well to narrower aspect ratios, such as 4:3 or 16:9 for full screen television, and would have to be pan and scanned as a result. Film grain has become less of a concern because of the availability of higher-quality film stocks and digital intermediates, although anamorphic format - due to its use of the full negative frame to record a smaller image – always yields higher definition than non-anamorphic format (provided the anamorphic projection lens, which is technically more demanding, is adequate).
The aperture of the lens (the entrance pupil), as seen from the front, appears as an oval.
Anamorphic scope as a printed film format, however, is well established as a standard for widescreen projection. Regardless of the camera formats used in filming, distributed prints of a film with a 2.39:1 (1024:429) theatrical aspect ratio is always in anamorphic widescreen format. Due to many movie theaters around the world not needing to invest in special equipment to project this format, it has become standard equipment in many cinemas.
Aspect ratio [edit]
One common misconception about the anamorphic format concerns the actual width number of the aspect ratio, as 2.35, 2.39 or 2.4. Since the anamorphic lenses in virtually all 35 mm anamorphic systems provide a 2:1 squeeze, one would logically conclude that a 1.375∶1 full academy gate would lead to a 2.75∶1 aspect ratio when used with anamorphic lenses. Due to differences in the camera gate aperture and projection aperture mask sizes for anamorphic films, however, the image dimensions used for anamorphic film vary from flat (spherical) counterparts. To complicate matters, the SMPTE standards for the format have varied over time; to further complicate things, pre-1957 prints took up the optical soundtrack space of the print (instead having magnetic sound on the sides), which made for a 2.55∶1 ratio (ANSI PH22.104-1957).
Anamorphic 4-perf camera aperture is slightly larger than projection aperture
The initial SMPTE definition for anamorphic projection with an optical sound track down the side ANSI PH22.106-1957 was issued in December 1957. It standardized the projector aperture at 0.839 × 0.715 inches (21.3 × 18.2 mm), which gives an aspect ratio of c. 1.17∶1. The aspect ratio for this aperture, after a 2× unsqueeze, is 2.3468…∶1, which rounded to the commonly used value 2.35∶1.
A new definition issued in October 1971 as ANSI PH22.106-1971. It specified a slightly smaller vertical dimension of 0.700 inches (17.8 mm) for the projector aperture, to help make splices less noticeable to film viewers. After unsqueezing, this would yield an aspect ratio of c. 2.397∶1.Four-perf anamorphic prints use more of the negative's available frame area than any other modern format, which leaves little room for splices. As a consequence, a bright line flashed onscreen when a splice was projected, and theater projectionists had been narrowing the vertical aperture to hide these flashes even before 1971. This new projector aperture size, 0.838 × 0.700 inches (21.3 × 17.8 mm), aspect ratio 1.1971…∶1, made for an un-squeezed ratio of 2.39∶1. This is commonly referred to by the rounded value 2.40∶1 or 2.4∶1.
The most recent revision, SMPTE 195-1993, was released in August 1993. It slightly altered the dimensions so as to standardize a common projection aperture width (0.825 inches or 21.0 mm) for all formats, anamorphic (2.39∶1) and flat (1.85∶1). The projection aperture height was also reduced by 0.01 inches (0.25 mm) in this modern specification to 0.825 × 0.690 inches (21.0 × 17.5 mm), aspect ratio 1.1956…∶1, which is commonly rounded to 1.20∶1, to retain the un-squeezed ratio of 2.39∶1.[10] The camera's aperture remained the same (2.35∶1 or 2.55∶1 if before 1958), only the height of the 'negative assembly' splices changed and, consequently, the height of the frame changed.
Anamorphic prints are still often called 'Scope' or 2.35 by projectionists, cinematographers, and others working in the field, if only by force of habit. 2.39 is in fact what they generally are referring to (unless discussing films using the process between 1958 and 1970), which is itself usually rounded up to 2.40 (implying a false precision as compared to 2.4). With the exception of certain specialist and archivist areas, generally 2.35, 2.39 and 2.40 mean the same to professionals, whether they themselves are even aware of the changes or not.
Lens makers and corporate trademarks[edit]
There are numerous companies that are known for manufacturing anamorphic lenses. The following are the most well known in the film industry:
Origination[edit]
- Panavision is the most common source of anamorphic lenses, with lens series ranging from 20 mm to a 2,000 mm anamorphic telescope. The C-Series, which is the oldest lens series, are small and lightweight, which makes them very popular for steadicams. Some cinematographers prefer them to newer lenses because they are lower in contrast. The E-Series, of Nikon glass, are sharper than the C-Series and are better color-matched. They are also faster, but the minimum focus-distance of the shorter focal lengths is not as close. The E135mm, and especially the E180mm, are great close-up lenses with the closest minimum focus of any long Panavision anamorphic lenses. The Super (High) Speed lenses (1976), also by Nikon, are the fastest anamorphic lenses available, with T-stops between 1.4 and 1.8; there is even one T1.1 50mm, but, like all anamorphic lenses, they must be stopped-down for good performance because they are quite softly focused when wide open. The Primo and Close-Focus Primo Series (1989) are based on the spherical Primos and are the sharpest Panavision anamorphic lenses available. They are completely color-matched, but also very heavy: about 5–7 kg (11–15 lb). The G-Series (2007) performance and size comparable with E-Series, in lightweight and compact similar to C-Series. The T-Series (2016), Panavision's latest anamorphic lens series, is designed for digital cameras initially, but also film camera compatible through specific re-engineering at Panavision.
- Vantage Film, designers and manufacturers of Hawk lenses. The entire Hawk lens system consists of 50 different prime lenses and 5 zoom lenses, all of them specifically developed and optically computed by Vantage Film. Hawk lenses have their anamorphic element in the middle of the lens (not up front like Panavision), which makes them more flare-resistant. This design choice also means that if they do flare, one does not get the typical horizontal flares. The C-Series, which were developed in the mid-1990s, are relatively small and lightweight. The V-Series (2001) and V-Plus Series (2006) are an improvement over the C-Series as far as sharpness, contrast, barrel-distortion and close-focus are concerned. This increased optical performance means a higher weight, however (each lens is around 4–5 kg [8.8–11.0 lb]). There are 14 lenses in this series—from 25 mm to 250 mm. The V-Series also have the closest minimum focus of any anamorphic lens series available and as such can rival spherical lenses. Vantage also offers a series of lightweight lenses called V-Lite. They are 8 very small anamorphic lenses (about the size of a Cooke S4 spherical lens), which are ideal for handheld and Steadicam while also giving an optical performance comparable to the V-Series and V-Plus lenses. In 2008 Vantage introduced the Hawk V-Lite 16, a set of new lenses for 16 mm anamorphic production, as well as the Hawk V-Lite 1.3× lenses, which make it possible to use nearly the entire image area of 3-perf 35 mm film or the sensor area of a 16:9 digital camera and at the same time provide the popular 2.39:1 release format.
- Carl Zeiss AG and ARRI developed their Master Anamorphic lens line, debuted on September 2012, to provide minimum distortion and faster aperture at T1.9. It's a totally new lens design which different from third-party modified Zeiss-based anamorphics such as JDC and Technovision.
- Cooke Optics also developed their Anamorphic/i lens line, providing T2.3 aperture and color-matched with other Cooke lens line, which marketed as their 'Cooke Look' feature. Same as Zeiss, it's a totally new lens design which different from third-party modified Cooke-based anamorphics such as JDC and Technovision. Besides, Cooke also developed its Anamorphic/i Full Frame Plus in 1.8× squeeze ratio for full frame cameras.
- Angenieux: Angenieux first zoom for 35 mm film camera, the 35-140 mm, was equipped with a front anamorphic attachment built by Franscope. The 40-140 anamorphic was used on several Nouvelle Vague movies such Lola (1961) or Jules and Jim (1962). Panavision adapted the Angenieux 10× zoom for anamorphic productions. The 50-500 APZA was part of the standard anamorphic production package supported by Panavision from mid 1960s to the end of the 1970s. It has been used in numerous movies including The Graduate (1967), MASH (1970), McCabe and Mrs Miller (1971), Death in Venice (1971) and Jaws (1975). In 2013 and 2014 Angenieux released a new series of high end anamorphic zooms. These lenses, the 30-72 and 56-152 Optimo A2S are compact and weighs less than 2.5 kg.
- Joe Dunton Camera (JDC): Manufacturer and rental house based in Britain and North Carolina, which adapts spherical lenses to anamorphic by adding a cylindrical element. Its most popular lenses are the Xtal Xpres series (pronounced 'Crystal Express'), which were built by Shiga Optics in Japan from old Cooke S2/S3 and Panchro lenses. They have also adapted Zeiss Super Speeds and Standards (the Speedstar series), as well as Canon lenses. JDC was purchased by Panavision in 2007.[11]
- Elite Optics, manufactured by JSC Optica-Elite Company in Russia and sold in the United States by Slow Motion Inc.
- Technovision, a French manufacturer that, like JDC, has adapted spherical Cooke and Zeiss lenses to anamorphic. Technovision was purchased by Panavision in 2004.
- Isco Optics, a German company that developed the Arriscope line for Arri in 1989.
Projection[edit]
- ISCO Precision Optics is a manufacturer of theatrical cinema projection lenses.
- Panamorph is a manufacturer of hybrid cylindrical / prism based projection lenses specialized for the consumer home theater industry.
- Schneider Kreuznach, (also called Century Optics) makers of anamorphic projection lenses. The company also manufactures add-on anamorphic adaptor lenses that can be mounted on digital video cameras.
Super 35 and Techniscope[edit]
Although many films projected anamorphically have been shot using anamorphic lenses, there are often aesthetic and technical reasons that make shooting with spherical lenses preferable. If the director and cinematographer still wish to retain the 2.40:1 aspect ratio, anamorphic prints can be made from spherical negatives. Because the 2.40:1 image cropped from an Academy ratio 4-perf negative causes considerable waste of frame space, and since the cropping and anamorphosing of a spherical print requires an intermediate lab step, it is often attractive for these films to use a different negative pulldown method (most commonly 3-perf, but occasionally Techniscope 2-perf) usually in conjunction with the added negative space Super 35 affords.
However, with advancements in digital intermediate technology, the anamorphosing process can now be completed as a digital step with no degradation of image quality. Also, 3-perf and 2-perf pose minor problems for visual effects work. The area of the film in 4-perf work that is cropped out in the anamorphosing process nonetheless contains picture information that is useful for such visual effects tasks as 2D and 3D tracking. This mildly complicates certain visual effects efforts for productions using 3-perf and 2-perf, making anamorphic prints struck digitally from center cropped 4-perf Super 35 the popular choice in large budget visual effects driven productions.
See also[edit]
References[edit]
- ^'Anamorphosis – Definition and meaning'. Collins English Dictionary. Retrieved May 9, 2020.
- ^'Origin and meaning of prefix morpho-'. Online Etymology Dictionary. Retrieved May 9, 2020.
- ^'Origin and meaning of prefix ana-'. Online Etymology Dictionary. Retrieved May 9, 2020.
- ^ abKonigsberg, Ira. The Complete Film Dictionary Meridian. 1987. 'Anamorphic lens' pp. 11-12
- ^Michael Svanevik and Shirley Burgett, 'Menlo’s Mild-Mannered Film Wizard: Motion Picture Inventor Leon Douglass Deserves Historical Niche', Palo Alto Daily News (July 5, 2008) pp. 6-7
- ^US Grant 2890622A, Walter Wallin, 'Anamorphosing system', published 11 August 1954, issued 16 June 1959, assigned to Panavision Inc
- ^US Grant 3165969A, Frank George Gunn, 'Photographic production of anamorphous records', published 24 October 1955, issued 19 January 1965, assigned to Technicolor Corp of America
- ^US Grant 1829634A, Henri Chrétien, 'Taking and projection of motion pictures and films therefor', published 28 January 1929, issued 27 October 1931
- ^Why is anamorphic bokeh oval?
- ^Hart, Martin.(2000). Widescreen museum 'Of Apertures and Aspect Ratios' Retrieved July 8, 2006.
- ^'Panavision to Acquire Camera Assets of Joe Dunton & Company'. PR Newswire. August 15, 2007. Retrieved February 1, 2013.
External links[edit]
- 'Of Apertures and Aspect Ratios'. Widescreen Museum.
- Mitchell, Rick. 'The Widescreen Revolution'. Operating Cameraman. Society of Camera Operators (Summer, 1994). Archived from the original on December 27, 2008. Retrieved July 6, 2013.
Retrieved from 'https://en.wikipedia.org/w/index.php?title=Anamorphic_format&oldid=973460535#2.39'
Anamorphic Lens Helios 44-2 2/58mm
What is an Anamorphic Lens
When you watch a movie, you've probably noticed those black bars along the top and bottom of the image. Movies are produced in various 'aspect ratios' (the ratio of the width:height of the image). Some movies are produced in 16:9 aspect ratio. If you watch these movies on an older non-HD television (which has a 4:3 aspect ratio), then you will get black bars above and below the image. If you have a newer HDTV with a native 16:9 'wide screen' then you won't get any black bars since the aspect ratio of the HDTV matches the aspect ratio of the movie. However, some movies are produced in 2.35:1 'Cinema Scope' format. When watching a 2.35:1 movie, even on your widescreen HDTV, you will still get black bars on the top and bottom of the image.
Currently, there are no televisions or projectors that have a native 2.35:1 aspect ratio. But there are several ways to remove these black bars to get the full Home Cinema Scope experience.
First, of course, you need a 2.35:1 aspect ratio screen. You can buy screens in this aspect ratio, or make one yourself. Some people just paint a large wall or piece of material that hangs on the wall. In my case, I stretched 'black out' fabric over a large screen-door frame. You can buy the metal strips that go around the edge of a screen-door at the hardware store. Just mount these strips to a large sheet of plywood, then stretch the black-out fabric just as if it were screen-door mesh. It makes a great screen.
Once you have a wide enough screen, the easiest way to eliminate the black bars is to zoom your projector so that the black bars are projected above the top of the screen and below the bottom of the screen. Essentially, you just zoom out until the width of the image fills the width of your screen. If you have a dark-colored wall, or cover it with black felt, then you'll never notice the light-spill over the top and bottom of the screen.
I used this method for years and it worked fine. The problems with this method is that you are enlarging the entire image, making the pixels larger, and are wasting the brightness and resolution from the black bars which are still being projected above and below your screen. Also, newer projectors often cannot zoom an image enough to fill the screen, and might also require lens shift adjusting to center the image vertically on your screen.
The solution to this, and the best way to achieve Home Cinema Scope, is using a special lens in front of the projector called an 'Anamorphic Lens'. An 'Anamorphic Lens' will stretch (or compress) an image in one dimension (vertically or horizontally). Most projectors have a 'zoom mode' that stretches the image vertically and eliminates the black bars. Rather than projecting 'black' and wasting those pixels, all vertical pixels are used for the movie image itself. This vertical stretch will cause people and objects on the screen to look tall and skinny. However, once the projector is displaying the full image vertically, you can then use an Anamorphic Lens to stretch the image horizontally to restore the correct aspect ratio.
That's a lot of words! Let's look at some pictures to understand this better:
Normal 2.35:1 Movie on a 16:9 widescreen HDTV
This is what you are probably used to seeing on your HDTV. Those annoying black bars on the top and bottom. Now let's project this onto a 2.35:1 screen:
Normal 2.35:1 Movie on a 2.35:1 Cinema Scope screen
(click for larger image)
Yes, I can hear you already: 'This is even worse!' Now you have black bars on the top and bottom AND on the left and right! Patience..this is just the beginning. Now, let's activate the projector mode that stretches the image to fill the entire vertical height of the screen. On my Infocus Screenplay 7205 projector, this mode is called 'Letterbox':
2.35:1 Movie on a 2.35:1 screen in Letterbox 'stretch' mode
(click for larger image)
This stretch is just coming from the projector's 'Letterbox' mode. No lens is used yet. Notice that C3PO and R2D2 look stretched (tall and skinny). This is what the lens will fix. When an Anamorphic Lens is placed in front of the projector, we get this final image:
2.35:1 Movie on 2.35:1 screen in Letterbox stretch mode with Anamorphic Lens
(click for larger image)
Now that's looking nice! No black bars at all. And since the full vertical resolution of the projector is being used, the image remains nice and bright and sharp. Static images really only provide part of the story. Master of typing 3 10 0. I can't convey the emotional immersion that results in watching the full Cinema Scope image rather than the first image that only utilized the middle of the screen. It feels like the same difference between watching a movie on TV vs watching it in the theater.
Of course, the downside to using a 2.35:1 screen is that when you watch 16:9 format material (or regular 4:3 format television), then you have black bars on the left and right of the image instead of the top and bottom. This kind of setup is called a 'Constant Image Height' (CIH) because the height of the image remains the same no matter what you are watching. This is exactly how normal movie theaters work. The image is always the same height, but the theater has retractable curtains on the left and right side of the screen that they can use to adjust the width of the screen depending upon the aspect ratio of the movie being shown. You can add curtains to your own home theater to provide the same feature. In my case, I just live with the black bars on the left and right. But masking the left and right bars with curtains is much easier than masking the top and bottom black barsin a normal HDTV setup.
Making an Anamorphic Lens using Prisms
Most people who want a Home Cinema Scope setup simply purchase a commercial Anamorphic Lens, or purchase a high-end projector that already has such a lens attached. But these lenses typically cost over $1000. You might think that it would be very difficult to make your own Anamorphic Lens. You'll be surprised to learn that making your own Anamorphic Lens is actually a very easy DIY project (even easier than making your own 2.35:1 screen).
The secret is 'prisms'. If you remember back to your high school science class, a prism is often used to split a beam of light into a rainbow (think of the cover of the 'Dark Side of the Moon' by PinkFloyd). Whenever a beam of light hits a surface, some light is reflected, and some light is 'refracted' (or bent). Notice that as the beam of white light hits the surface of the prism, each color is refracted (bent) a different amount. Then, when each color hits the second edge of the prism (on the right), eachcolor is bent even more.
Now, imagine putting two prisms next to each other, but reversed so that the second prism takes the rainbow from the first prism and converts it back into a white beam of light. With two prisms, you put a white beam in, and you get a white beam out. But by adjusting the angles of the prisms relative to each other, you can bend the outgoing beam of light and essentially magnify it. This is exactly how an Anamorphic Lens works!
There is a wonderful web site that uses a Java Applet to demonstrate how prisms work: NTNUJAVA Virtual Physics Prism site
Anamorphic Lens using 2 Prisms
The prisms shown in the above diagram more closely match the prisms that arecommercially available in large sizes. Remember that the image coming from yourprojector starts with a small size of just a couple inches. But when the lightbeam reaches the screen, it is much larger. The beam of light increases in sizeas you get further from the projector. So these prisms need to be several inchesin size to handle the full beam from the projector.Where to get Prisms
There are several ways to get a prism the size that you need. Many people have made their own prisms by cutting glass to make the surfaces, then seal the glass together to make a hollow prism, and then fill it with water or mineral oil. You can make very large prisms in this way. However, most home theater owners don't like the idea of potentially leaking prisms hanging from the ceiling in front of their projector. Sealing these glass prisms so that they do not leak over a long period of time can be difficult.
Fortunately, an inexpensive solution is available. Several companies now manufacture crystal 'award' plaques. These crystal plaques are meant to be engraved with some award and then sit on your desk or a shelf. They are wedge-shaped, with the base of the plaque larger than the top of the plaque. If you look at the side profile of these crystal wedges, they match the picture of the prisms shown above. They come in several sizes, such as 4'x6' (measuring the front face that you would normally have engraved) up to 6'x7.5'.
There are several sources for these prisms. In the U.S., I have used MassillonPlaque. In Australia you can use EvRight. Ifyou call your local award plaque company, they can probably point you to othersources. At the time that I purchased the small prisms, they were about$29 each (without engraving). Be sure to call the company to find out ifblank wedges are available. Also, the blank wedges are usually cheaperthan the prices listed on the web site, since they don't need to charge you forany engraving.
These are not plastic or acrylic. They are very heavy, crystal glass. I don't think they are 'lead crystal', but are some modern variation. I've even heard some people say that it's the same stuff they make spacecraft windows out of. What's important is that they are optically very clear and the surfaces are very flat and uniform. It's important to get two identical prisms, since the second prism needs to cancel the rainbow created by the first prism. If there are differences in the prism angles, or if the surfaces are not perfectly flat, then you will get more 'chromatic aberration' (which will look like blurring at the edges of the screen).
Initial Testing
If you are planning to build your own Anamorphic Lens, I recommend that you just purchase a couple of prisms and then start playing with them. It's impossible to provide exact construction dimensions and angles because each projector setup will be slightly different. The angle between the two prisms will depend upon the throw distance of your projector, and the size of your screen. So, if possible, just put your projector on a table and place the prisms in front of the projector. Then start playing with the angles. In my case, I placed the prisms on a piece of paper, and when I had the prisms adjusted, I just traced the outline of the prisms onto the paper as a template for construction (more on that later).
Just set up the prisms in roughly the configuration shown in the 2-prism diagram above. As you adjust the angle of the first prism, you will be adjusting the right-edge of the image on the screen. As you adjust the angle of the second prism, you will be adjusting the left-edge of the screen. I placed some tape on my screen (the blue painters tape that doesn't leave any marks or residue) and make marks for the proper 2.35:1 size. Then I just adjusted the prism angles until the image expanded to hit the marks.
In fact, it's so easy to set this up and align it, that it's even possible to use these prisms for temporary setups where you just put the projector on the coffee table, then place the prisms in front of it. It's not perfect, but it works easier than you might think. But after a few minutes of playing with the prisms you will get the hang of it. The initial results are so impressive, that you might be tempted to just start watching movies already! Trust me..you'll want to watch your entire collection of 2.35:1 movies all over again!
Building an Enclosure
Playing with the prisms on the coffee table is fun. But eventually you are going to want to mount these prisms in some type of enclosure that you can place in front of your projector. In my case, my projector hangs from the ceiling. So I needed an enclosure that could also hang from the ceiling. The type of enclosure that you need will really depend a lot on where you have your projector mounted already.
Because we are building a 'horizontal stretch' lens, you do not need to move your current projector. Some people like to make a 'vertical compression' lens (which you can also make using two prisms) and then move the projector so that it projects the full width of the 2.35:1 image, and then use the lens to compress the image vertically to fit on the screen. Some people feel that you get a better quality image using vertical compression, but I didn't want to move my existing projector location, and I also wanted a way to move the lens out of the way when I'm not watching 2.35:1 movies.
Enclosures can be built out of a variety of materials. The most common materials seem to be either aluminum or wood, depending upon your preference (and what tools you have available). I made my own enclosure out of 1/2' MDF because it is cheap and easy to work with. My design was based upon the original 'Aussiemorphic Lens' from Mark Techer. His blog provided my initial inspiration. Ideas from many people in the DIYAudio.com forum were also used. In particular, I wanted to be able to easily adjust the prism angles once they were inside the enclosure for fine tuning then lens.
To start, I needed to attach bolts to the top and bottom of the prism which would be used as rotation points. Just gluing a flat-head bolt to the prism doesn't work very well. However, if you first cut a triangle of plexiglas (or other material..some have just used cardboard), then you can drill a hole in the plexiglas, countersink it for the screw head, then place the screw between the prism and the plexiglas and epoxy the entire piece of plexiglas to the prism.
Remember that the 'top and bottom' that we are gluing screws to are really the left and right edges as shown in the picture of the award plaque sitting on a desk. When placed in front of the projector beam, these become the top and bottom edges within the enclosure. The screws fit into holes in the top and bottom of the enclosure with wing nuts. Loosening the nuts allow the prisms to be rotated to adjust the alignment.
It is also very important to mask the sides of the prisms. As I mentioned earlier, whenever a beam of light hits a surface, part is refracted (bent), but part is reflected. With these glass prisms, a reflection from one surface is only about 4% of the main beam intensity. A double-reflection is only about 0.1% of the main beam intensity. However, in a dark theater, even a 0.1% reflection is visible on the screen. Most of these reflections exit from the two ends of the prisms. I just used black electrical tape to mask the ends.
Once each prism has a bolt plate glued to the top and bottom, then it's time to make the enclosure itself.
The enclosure is shown from the top (upper-left picture), with the projector at the top and the screen towards the bottom. The bottom-left diagram is looking from the screen towards the projector through the box. The enclosure really is a fairly simple 4-sided box. As shown in the bottom-left view, the top is screwed to the sides, while the bottom is glued and held to the sides using splines (or biscuits if you have a biscuit-joiner). I tried to minimize screws and only use them where it was necessary, since the top needs to be removed to change or clean the prisms. But MDF doesn't hold screws very well, so biscuit joints and glue work best.
The top view also shows the tentative position of the prisms (looking down on the prisms). The circles represent the screws that were glued to the top and bottom of the prisms. The inside of the enclosure is lined with black felt that is glued to the MDF using a spray adhesive (rubber cement also works well).
Once the enclosure is built, then you need to decide how to mount it in front of your projector. In my case, my projector is flush mounted with the ceiling. Since I wanted to be able to remove the lens from the front of the projector, I designed a 'sled' which attaches to the ceiling via two drawer slides. The sled itself is just another piece of MDF, painted white to match the ceiling. To attach the enclosure box to the sled, I made a U-shaped bracket using oak. This bracket needs to be stronger than MDF, so a hardwood like oak or maple would work well. An aluminum bracket would also work well. The bracket is slotted to allow adjustment on the sled, and also adjustment to the enclosure.
OK, time for some real pictures of the actual enclosure mounted on the ceiling. I apologize for not having any pictures during the actual construction..I didn't have my camera yet.
The side image shows an extra bit of felt glued to the back of the enclosure near the projector. This prevents some of the reflections generated by the prisms from getting out and reduces the light spill onto the walls. An additional piece of felt is actually glued to the back of the box with just a circular cutout for the projector lens. You can see the wing nuts on the bottom of the enclosure box that are used to adjust the prism angles. You can also see the wing nuts on the side which are used to attach the bracket to the box, and the slots where the bracket is bolted to the white sled. If you look closely, you can see the plexiglas that is epoxied to the top of the prism. You can also see the black electrical tape that covers the wide end of the prism (on the right side of the prism in the first image).
Here is the enclosure moved to the side of the projector:
This gives a better view of the 'sled' which is attached to the ceiling using two drawer slides. To move the lens out of the way, I simply push the entire lens assembly to the left. The ceiling is low enough that it is easy for me to just reach up to move the lens. If you had a higher ceiling, then you could attach a cord to the sled to drag it left or right. The drawer stops prevent the sled from being moved too far in one direction or the other. You can actually build the sled even better and can completely hide the drawer slides even when the lens is moved out of the way. I got my upside-down directions messed up, which is the only reason the drawer slides show. But at least it makes the picture easier to understand.
Notice that the bracket is designed to allow the lens box to tilt up and down. A slight tilt is needed to improve the geometry of the image. You will get pin cushioning in the corners of the image, and by tilting the entire lens you can minimize this geometry distortion and make it more uniform on the top and bottom of the image. I actually zoom my image out just a bit so that the pin cushioning is masked by the black felt around the outside edge of myscreen.
Performance Tests
Uniformity
When watching movies, you will be amazed at the performance of this lens. The last Star Wars image shown above is an actual picture using this lens. However, if you connect a computer to the projector and start playing with test images, then you will learn a bit more about the potential short-comings of this DIY lens. But before I discuss these details, I can't stress enough how minor they really are. It's easy to get depressed when looking at test images. The test images are useful to try and improve the design, but the overall result of watching movies is much more positive than you might think looking at the test images.
The first issue is the uniformity of the aspect ratio. Converting a 16:9 image to a 2.35:1 image requires a 133% stretch. However, if you put a grid onto the screen and actually measure the rectangles, you will discover that the rectangles in the center of the screen are 127%, and the rectangles on the right and left edges of the screen are 142%. The perfect 133% stretch only occurs in the left-center and right-center of the screen. It is uniform from top to bottom. It is only left-to-right that shows the aspect ration change.
Fortunately, the human eye is not sensitive to these kind of changes in aspect ratio. Even when moving an animated circle around the screen, it is very difficult to detect the aspect ratio changes to the circle as it moves left and right on the screen from the normal viewing distance (about 10 ft from the screen in my case, which is closer than most for a 124'x53' screen).
Also, according to reports from people who own commercial Anamorphic Lenses, the commercial lenses suffer from the same aspect ratio non-uniformity.
Chromatic Aberration (CA)
A larger problem is the color problems at the edges of the screen. As we know, the first prism is splitting the light beam into a rainbow. If the second prism can't precisely undo this, then you won't get a white beam on the screen. And in fact, it is impossible for a flat prism surface to perfectly correct the rainbow from the first prism because the light beam is actually a spherical wave and not a flat wave. So, as you move towards the right and left edges of the screen, the light beam starts to get split more into a rainbow. This gives a slightly colored edge to some objects. Here are some very close up pictures of the test grid in the middle of the screen, and then on the right edge of the screen:
Notice how the horizontal lines are still perfectly black in both images. However, the vertical grid lines are black in the left image, but look like rainbows in the right image. If you look closely, you will see that the black line is blue and has a yellow edge on the right side of it. This makes the image look blurry. Notice that you can actually see the DLP pixel structure in these images, and that the rainbow is about two pixels wide. Now here is a full view of the same grid on the entire screen:
(click for larger image)
Note that the geometry pin cushioning and the change in brightness across the screen is caused by the digital camera and not the lens or projector. But you can still tell that the left-most and right-most parts of the screen are a bit blurrier than the center of the image.
This chromatic aberration can be reduced by using four prisms instead of two. You essentially 'double' each prism by putting another prism next to it in the exact same orientation. Essentially you are making two prisms with a larger internal angle. This allows you to reduce the angles of the prisms relative to the light beam, resulting in less bending of the light. The less the light beam is bent, then the smaller the rainbow on the edges.
At normal viewing distance, the eye cannot really detect the rainbow itself. Macbooster pro 8 0 2. It's very hard to see any color edges on objects in movies. The only real effect of this problem is that it makes the image on the left-most and right-most parts of the screen slightly blurrier. While this is noticeable when using a computer image, it really isn't very noticeable during movies. However, this is certainly something to be improved in these lenses and something the commercial lenses do a better job of correcting.
Reflections
As mentioned before, each time a beam of light hits a surface, it is both refracted (bent) and reflected. In a dark theater, these reflections can be quite visible and quite distracting if you don't do something to get rid of them. Fortunately, the majority of reflections are at angles that can be easily blocked by the enclosure. When you first play with the prisms without an enclosure, however, you will be able to see all of the different reflections around the side and back walls of your room.
Fortunately, all we need to worry about are reflections that end up on the front screen. As it turns out, there is a single reflection from the 2-prism lens that can appear on the front screen. This reflection occurs just as the beam of light is exiting the final surface of the final prism. The light reflects internally within the prism, then reflects again on the first surface of the same prism, resulting in a beam that hits the screen near the first beam. Fortunately, since this is a double-reflection, it's intensity is approximately 0.1% of the main beam intensity. Also, given the geometry of the lens shown in this article, only the right-most part of the image is reflected onto the left-most part of the screen. Given the low intensity, you can only see this reflection when there is a bright object on the right side of the screen and the left side of the screen is very dark. In some cases, you might see a dim reflection of credits at the end of some movies, since they are moving (making the reflection easier to detect) and are typically bright white letters on a black background. However, this reflection is so dim that I wasn't able to get a picture of it in my camera. And most movies do not show this reflection at all. The best test case I have for demonstrating the reflection is the very opening of the James Bond Goldeneye movie, where the white spot light moves from left to right (the trademark James Bond opening where the white spotlight turns red and then zooms into the actual first action scene). When the white spotlight is on the right-most part of the screen, you can see a dim reflection on the left side of the screen.
Using more prisms to reduce chromatic aberration unfortunately provides more surfaces to generate reflections. A 4-prism lens has several other reflections that can hit the screen. I find myself more sensitive to reflections and less sensitive to chromatic aberration, so I prefer the 2-prism lens. But you might want to play with four prisms to see what you think yourself.
Unfortunately, the only way to reduce this reflection is to coat the prisms with some sort of non-reflective coating, without effecting the optical clarity of the prism. Such coatings are very expensive and are something you can expect on commercial lenses, but difficult to achieve for DIYers.
Conclusions
I cannot stress enough how immersive a constant-image-height (CIH) theater can be. If you can remember your first thrill at having a large 'movie theater' in your home, going to a 2.35:1 screen with CIH will give you that same thrill all over again. I had thought for the past five years that just zooming the projector was good enough (and it was certainly better than just a 16:9 screen). But using an Anamorphic Lens instead of just zooming the projector is simply an amazing difference in picture quality. When I tell people about CIH, I always warn them that it's almost a curse: once you have experienced a CIH theater, then you never want to go back to a simple HDTV or 16:9 screen again.
Fortunately, thanks to many DIYers, it is possible to construct your own Anamorphic Lens fairly easily and inexpensively. It has certainly been one of the most satisfying projects I have ever done for my theater. I'll leave you with an image that just seems to express my happiness with this lens.
Acknowledgements
I owe my thanks to many people who have contributed ideas to this project. Most of these people have contributed to the very long forum thread on the DIYAudio.com site. If you are serious about a DIY Anamorphic Lens, then you own yourself to spend the hours it will take to read this entire thread. Mostly I want to thank Mark Techer and his Aussiemorphic Lens blog, not to mention his many early posts about building water and oil prisms before the crystal wedges were discovered. Then I should thank Steve Scherrer for his discovery and post of the U.S. source for these prisms, and for his ideas on attaching screws to the prisms to make them adjustable. Also, thanks to dvarma who posted a PDF link to his description of an enclosure that used a drawer slide to attach it to the ceiling, which was an inspiration to my own enclosure bracket.
I wish the best of luck to anyone who attempts this project. Rather than contact me directly, I encourage you to post questions and your own experiences to the DIYAudio.com thread mentioned above so that you can get help from everyone in that forum and help inspire others to built their own CIH Theater.
MikeP