It may come as a shock with such a surprisingly bold claim, and skeptics will be the first to disprove of it. But if you really go down to the fundamentals, the suspension of silver halide molecules on the emulsion layer of the acetate film does indeed behave exactly like a modern image sensor would. But before we discuss further about this, let’s take a look at what does Analogue and Digital really mean.
There is no such thing as Analogue Photography ~ Solarex Imaging
Analogue Vs. Digital
Analogue means a continuously variable value, stretching between the two extreme values. This simply means that it can be anywhere along the value line between the two extremes at any given time. Let’s take the example of the two extreme ends as being 0 (zero) and 1 (one) – Being of a continuously variable value means that at any given time, the reference point can be 0.0027, 0.1005, 0.2226, 0.4896, 0.7775, or 0.9986, and a whole lot more… Here, we’re only limiting to four decimal places only. Now, imagine that we have ten decimal places… Or even 20 decimal places… Can you think how big the variable is right now?
In contrast, Digital means a distinct value of either extreme values. Let’s take a look at the same example, where the two extreme values are 0 (zero) and 1 (one) – The reference point can only either 0.0000 (zero) or 1.0000 (one) at any given time.
So how does this relate to image capture in a camera? How is it similar to film?
How Digital Camera Works
Digitally captured image on an image capture sensor means recording either image area (one) or non-image area (zero) as a series of dots that line the whole image sensor area. The combination of these image area (dots) and non-image area (no dots) will artistically create an image out that series of dots that the human eye can relate to as a photo. Now, we all know that to be recorded as an image area (dot), that particular point of sensor must be “activated” and will this record as “on”, while the non-image area (no dot) will not be “activated”, and thus recorded as “off”. This is easy to comprehend, since there’s only two possibilities – either “on” or “off”, a distinctly digital value.
How Film Camera Works?
So now let’s take a look at what happens to film instead. As we all know, film consist of transparent acetate “film”, coated with a layer of emulsion of light sensitive silver halide molecules. Image is recorded when the individual silver halide molecule is exposed to light, elevating that individual silver halide molecule to a higher energetic level. The unexposed individual silver halide molecule will remain in its natural state of lower energetic level.
And when this “exposed” film is processed, the developer will chemically reduce the “excited” silver halide molecules more readily than the “non-excited” silver halide molecules. So by undergoing the developing stage, the “exposed” silver halide molecule will be reduced to metallic silver, which is opaque (image area). Elsewhere, the “non-exposed” silver halide molecule isn’t readily reduced by the developer, and will still remain as light-sensitive silver halide molecule within the emulsion layer.
At the fixing stage, the “non-excited” silver halide molecules will be removed by dissolving into the fixer and being flushed away, thus stripping the film from any remaining light-sensitive silver halide molecules. As a result, the unexposed area where the silver halide molecules were flushed away are now void, thus transparent.
Revelation – Film Really Is Digital
So let’s take a step back, and look at the overall picture – The exposed area (image) are now dotted with opaque metallic silver, while the non-exposed area (non-image) are transparent.
Well… What do you know?… The film image is actually made up of areas of opaque metallic silver (ones) and areas of transparent film (zeros). And it that doesn’t make film digital, I don’t know what does…
