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Industry Terms – Film Terms

Many of you would have heard the terms slide and slide film. Some may have heard the terms transparency or reversal. But what do these terms stand for, and what’s their correct usage?


Back in the days when film was king most people shot negative film (e.g. Kodak Gold 100 film or Fuji Reala 400 film) to record the original image. The original negative image was then converted to a positive during the printing process. So the print that you looked at wasn’t really the original, but a reproduction from the original negative film image.

It’s a little like when you’d buy a record (vinyl). The only way you could play it in your car was to copy it onto a cassette tape. The trouble was that this process of reproduction resulted in a loss of quality from one generation (e.g. vinyl) to the next (e.g. cassette tape). Interestingly, although most folks don’t know this, a loss of quality also occurs when a negative is reproduced as a print. In the audio example the loss occurs in the bass and treble. Similarly, when a negative is printed, shadow and highlight detail is likely to be lost in the resulting print, particularly when the original image was shot under relatively high contrast conditions.

The word Transparency can be used to describe a roll of film designed to record and process the original scene into a positive film image. The word transparency was also widely used to describe a single, unmounted positive film image. The term Trannie is actually a slang word for transparency, for which the correct abbreviation is trans.


While some photographers substituted the word Reversal for transparency, the word Reversal actually describes the process under which E6 compatible transparency film is processed. We can outline that process, in its current form, as follows:

Camera Exposure

During exposure silver halide crystals, contained with the film’s emulsion, are activated by light forming a latent (invisible, potential) image.

First Developer

During this step the film’s exposed silver halides are converted into metallic silver to produce a visible black and white negative image.

First Wash

Helps to stop the fist developer step and prevent chemical carryover into the Reversal Bath.

Reversal Bath

This step includes a chemical reversal agent that is absorbed into the film’s emulsion preparing it for the Color Developer step.

Color Developer

Any unexposed silver halides are converted into metallic silver. As the color developing agent is oxidised color dye is formed in each of the Red, Green and Blue sensitive layers. As a consequence of these two processes a positive color image is formed.


Contains formaldehyde that minimises fading of the color dyes over time.


The metallic silver is converted into silver bromide, which is easily dissolved by the Fixer. All that remains is the color dye image.


This step is recommended for low volume processors. It removes any remaining Bleach from the emulsion and extends the life of the Fixer.


The film is stabilized (e.g. fixed) to help prevent colors from fading.

Final Wash

The film is washed to remove chemical residue and promote longevity

Final Rinse

A Wetting Agent / Photo-Flo, to promote even drying, as well as an anti-fungal agent is included in this solution.


Excess water is removed as the film dries, within a dust-free environment



A Slide is simply a transparency that has been placed into a card or plastic mount, referred to as a slide mount, to provide easier and safer handling and allow it to be viewed through a slide projector.

We can summarise the above differences between these terms as follows:

  • Transparency = Film
  • Reversal = Process
  • Slide = A mounted transparency


© Copyright All Rights Reserved

Glenn Guy, Blue Sky Photography


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