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There was an article a few years ago entitled "Analog is Not the Opposite of Digital".

Film is not analog, period. I used to shoot film on a Canon AE-1 from the ’70s. Now I have a digital SLR from Canon, and they’re obviously extremely different. But we have to be careful not to confuse ‘old’ and ‘new’, with two very specific terms like analog and digital.

The word digital, to most people, refers to a device that can capture, store, or display data in a binary fashion. Ones and zeros, on and off, digital is all about numbers. Digital shouldn’t be confused with binary, of course, as digital simply means concrete values. Any system that utilizes solid values (or digits) is digital, binary is simply the most common system. Digital cameras capture light with a sensor, that light is converted into data (numbers), so the use of the word ‘digital’ for your cell phone camera or DSLR is accurate.

Analog, however, is a very abused word. I would venture a guess that the significant amount of readers have used the word ‘analog’ to refer to film cameras. If the new, fancy robot cameras are ‘digital’ then our aging film cameras are ‘analog’, right? Not at all. Older cameras capture light with film, which is basically plastic, gelatin, and silver halide. When you take a photo (perhaps of your dog drinking a beer), photons hit this material and produce a latent (invisible) image, that can later be brought into view by bathing the film in various chemicals. You could write hundreds of blog posts on film development alone, but the point is that film photography is a chemical process.

I understand the author's point about this misuse of the word "analog" in general, but it seems as though chemical film possesses many of the characteristics of an analog medium, in that it can capture a continuous spectrum of color values over a particular range.

Does this characteristic (or any other) of chemical film make it directly comparable to other analog media such as a record or a cassette, or does the fact that the method of storage of the light information is not a continuous wave like a phonograph record preclude it from being classified as such?

Since I know it will likely show up in a search for these topics, I had found Analog Photography appears to be a subfield of the art of photography, in which "progressively changing [the] recording medium" creates the image, regardless of whether chemical film or digital capture is used. The technique itself seems to be the analog process in that case, and not any sort of statement about the photographic medium.

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My Meta question regarding this topic. –  jonsca Jan 29 '13 at 6:43
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This is a very narrow definition of "analog". There aren't many analog devices if we use this definition. e.g. if a device uses charged particles (cassette tape) or mass (vinyl record), the possible values that can be stored are discrete. You'd have to go back to flywheels and cogs to have truly continuous values. –  nikie Jan 29 '13 at 7:39
    
@nikie How about in terms of the range of frequencies that tapes or records can represent? Or is that the "narrow" portion of the definition? In any case, if you expand on your points a bit, it might make a good answer. –  jonsca Jan 29 '13 at 7:50
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For someone attempting to split hairs about "analog," he or she doesn't understand "digital." Words like "concrete" and "solid" have no meaning. Digital is discretization as well as quantization. However, data may be quantized but not discretized and vice versa. I wouldn't put much stock into an article from a photographer with no background in EE/Physics. –  Bryan Jan 29 '13 at 22:00
    
@Bryan The word "concrete" also bothered me in this article, where he probably meant "discrete". –  Deve Jan 30 '13 at 7:03

1 Answer 1

up vote 5 down vote accepted

Film isn't absolutely "analog", as in continuous. Every individual silver halide molecule, after exposure and development, is either metalized or not; and there are a finite number of these molecules in every frame of film, thus quantizing the exposure measurement. However the density and location of the film grains and silver halide molecules is semi-randomized, which helps noise shape or dither the sampling, quantization and aliasing noise more than if they were in a regular grid with fixed step values.

So some current differences are not that film is in some sense a truly continuous measurement system (at least down to the Planck level), but more might be that the "sampling" is dithered, and also that the dynamic range may be higher than in the most common digital formats (8 bit integer per channel).

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