Reversal film

As slide film, slide film (Greek δια - "by" ) or reversal film is called a photographic film showing in a natural view of its development gray values ​​or colors.

After the development, and the cutting of the film results in individual slides which are often used for the projection.

Heyday

In the second half of the 20th century, the slide film was mass distribution. He noted at the time for amateur photographers an option for establishing a beneficial way color images. Despite the possibility of color photographs from negatives - and photos from digital data at the present time - be able to produce, the slide film has can always claim. His strength is - compared to the paper print - high dynamic range.

The preferred form of presentation slides is the projection. This characteristic is so typical that it is used in the form of the "slide show" in the computer presentation. From slides and paper prints are possible, however, the projection optimized for high contrast color slide circumference which can often be very limited reproduced on paper.

In 2001 had slide film to the 187 million -selling movies in Germany a share of 7%. The demand was, however, already declining in the years before.

The slide was in the cinema at home. Long decades was the ideal format in use on the Kinodiaformat 85 × 85 mm. Was projected with the same light as for the motion picture, so there was image projectors with the lime light, clean coal and Beck- carbon arc lamps.

And more portable

Black -and-white reversal films have a mixed of two different emulsions image layer. One approach is highly sensitive, mostly panchromatic sensitized and unsensitized the low sensitivity others. When taking pictures of the low-sensitivity silver salt by about ten times remains underexposed. After the development of a negative of the more sensitive silver salt that is bleached, i.e., converted into a soluble compound, and then removed from the image layer. The remaining salt undergoes complete it through exposure, blackening in a developing and the more usual treatment. The addition of the negative is now a fine-grained positive.

Color reversal films today are constructed as multi-layer films that are processed according to a chromogenic method. The dyes formed during processing with color couplers in the light sensitive layers. Color slide films are now developed in the standardized E-6 process.

Another film structure had the Kodak Kodachrome slide film: The color couplers here were not in the light-sensitive layers. Rather, the three emulsion layers were subjected in the course of processing in the K-14 process individually reversal development, with appropriate color couplers for each color in each with its own developer solution are. This method, which remained unchanged in the Broad since the introduction in 1935 in use, allows very thin photosensitive layers, which leads to greater focus - for decades Kodachrome slide films were sharper than other slide films. Kodachrome slide film could be developed due to the complicated K-14 process de facto only with Kodak. Kodak offered this service by the end of 2010.

In recent years, other movies have caught up. Currently ( 2012) apply the Fujichrome Provia 100F (normal color matching, extremely neutral gray balance ) and Fujichrome Velvia 50/100/100F (color enhanced for nature and landscape photography ) as the sharpest and finest grain slide film in the world. Noteworthy is the fine grain, sharpness and color saturation of Fujichrome Provia 400x, the same draws of these parameters with the 100ASA emulsions in the late 1990s.

The basic structure of reversal films and negative films is the same. This is basically the reverse development of a negative film or slide film negative development of a possible ( cross-processed ). The achievable results, however, are more likely to be described as "experimental". So you can develop a slide - reversal film with the C-41 process as for special applications and effects, which is really meant for color negative films. The result is high-contrast negatives with overly saturated colors. However, the negative development of black and white reversal films is likely to provide any useful results, since these films as well as the color reversal films usually have an existing colloidal silver anti-halation layer, which is removed only in the bleaching of a color process.

Most black and white films are negative films, not slide films. Exceptions were the black and white reversal films Agfa Scala, Fomapan R and the long gone -produced Agfa DD (Dia - Direct). In principle, you can indeed any black and white negative film by reversal development to make slide film ( cross-processed ), good results are achieved only with movies that have a colorless base. But black and white films for negatives have a gray colored layer support ( Grey base), which prevents the formation of halos. Meanwhile, there are methods for producing black and white slides, can elicit the appropriate films up to 800 line pairs per mm resolution, and therefore far more than color slide.

Diabetrachtung

The size of a small picture slides (24 mm × 36 mm ) is too low to be able to see it easily without any tool can. There is therefore slide viewer in which the slide is viewed through a magnifying glass. Here the ambient light or a small light bulb for lighting is mostly used. In such viewers usually both mounted slides and uncut film strips can be considered. Slide Viewer is also available in versions as Stereodiabetrachter.

With the help of slide projectors, the slides can be projected on a screen or matte screen. In general, the single slide must be framed so.

Slideshow

In the years of the millennium, the mass distribution of digital photography began. Along with this came the opportunity to view digital photos in a convenient way on the computer screen; example, as a self running sequence. For this type of image presentation, the name "Slide Show " prevailed. As a symbol of a stylized slide is often used. The stylization usually shows a framed slide with internal triangle ( = " playback ").

Advantages and disadvantages of slide film

Basics of the contrast range

The largest contrast difference in our everyday exist between the darkest of nights and blazing sunshine. One speaks here of a large dynamic range. There is no picture system that can fix the full contrast range of nature in an image. Therefore, the natural contrast range when shooting in the image storage must be reduced.

From all - not digital - imaging methods a slide has the largest range of contrast and the largest contrast differentiation. A standard comparison with the digital imaging methods is difficult as there is no benchmark comparison test.

The practical advantages of slide film are mainly in the high sharpness and color fidelity as well as the great tonal range of the slide. These properties of the slide film occur in the projection evident. The image quality of a projected mm slides has a high contrast ratio and differentiation.

Transfer by reducing the contrast range

The reduction of the natural contrast range in the slide and the negative film is tailored to the specific purpose ( projection or photo). If a photo (contrast 1:100) from the slide (contrast 1:1000) are made, the contrast range of the slides must be significantly reduced. For this, various technologies exist:

• The special white and black make for a much higher contrast ratio. While this is still below that of a slide, but above that of normal photographic paper.
• The contrast behavior produces a very good effect optimization.
• An additional compression of the tone values ​​can be achieved by contrast masks. Here, a black and white negative in the contact process is exposed so that the later addition with the slide results in the desired contrast range.

• Agfa- Digiprint was a self-contained process. It could be used only for input side and output side slides only photos on photo paper supply ( the Scan on a disk store was not possible). Digitization, however, is an open procedure.
• The scanner and optimization software is now much more sophisticated and omnipresent; Slide scanners are also available for the home user at moderate prices. Technologies such as Multi-Exposure help to get as much of the contrast range of the original.

If high-quality slides projected properly, you can get a very good impression of the natural color and brightness while shooting situation. The quality of this visual impression marks still a quality standard for other imaging methods.

In professional fields, slides were used until the 1990s, as their quality to be assessed was less complicated than the negatives.

Archiving

Most slides are unique; rarely duplicate slides are used. Generally uniques are exposed to a relatively high risk because of damage caused by dust, fingerprints, scratches, light and moisture are irreversible. Since slides have a gelatin layer, they are, like all other photo materials also against fungi and bacteria -prone. So may form holes in the course of years, the slide is destroyed.

It is possible to duplicate slides or digitizing. Problems here:

• The slide - duplication is a method analogous so always associated with a loss of quality.
• If high quality slides scanned with most other information, fast file sizes of a few hundred megabytes ( at 16 bit color depth) can occur. It is also difficult, a suitable imaging method for the preparation of these masses of data to find ( contrast range, contrast differentiation, color gamut ). With the progress of computer technology, but it is now also possible for home users to use slide scanner to create a digital archive of your own slide collection.

Decline by the digital photography and present situation

All manufacturers of chemical materials Photo suffered since the turn of the millennium more or less by the fall in demand in favor of digital photography. Of the former three major Diafilmherstellern Kodak, Agfa and Fuji only the Japanese Fuji could restructure their business model successful. Other manufacturers were ORWO, Konica, Foma and Ferrania.

Agfa -Gevaert broke up in November 2004 by the film and photo paper division; the then newly formed AgfaPhoto, in the production of photographic materials has been outsourced had already sign insolvency in May 2005. The not affected by the insolvency of AgfaPhoto Holding GmbH has since worked as a licensor of trademarks, rather than a producer. Thus there is produced on site since 2005 no Agfachrome Diafilme more.

In March 2007, the Japanese company Konica Minolta production of photochemical film and paper a completely. Thus disappeared the Konica slide films ( Konica Chrome, Konica Sinbi ) from the market.

In 2004 and 1996, the 3M Group subsidiary Ferrania Italian company went into bankruptcy. However, the production could be maintained until 2011, when Ferrania had to stop the film and photo production (eg Solaris slide films as well as many commercial brands) and fully adopted by the photochemistry.

Kodak had to stop the famous Kodachrome slide film because of declining demand and the high cost involved in June 2009. In January 2012, Kodak to file for bankruptcy, followed by the cessation of production of all remaining Kodak slide film ( Ektachrome, Elite Chrome) in March 2012.

So today is only the Fujifilm Corporation operates as a manufacturer of color slide. In July 2012, there was a consolidation of the Fuji- Diafilmsortiments, which still (as of November 2012) a good choice for professional and amateur Diafotografie offers ( Fujichrome Velvia and Fujichrome Provia ).

A black and white slide film by Czech manufacturer Foma is available under the name Fomapan.