Why do you call Film Analog?

[Bob Bell]

So as I read more and more threads on this site I keep reading the term Analog in reference to Film. I am very confused by this as I am an IT Professional and Analog is the opposite of Digital (1's and 0's) only in the sense of data transmission or capture. Like how a Vinyl record has continously changing quantities (bumps in the grooves) and a CD is an organized collection of 1's and 0's.

Film is not electronic in nature but rather chemical so I do not understand why someone would use Analog?

I'm sure there are other words that are inherently confusing as it seems to be a trend in photography lately, such as crop factor :)

[roteague]

Just the way people like to label things. It is something we all do.

You are right, film isn't analog, it is chemical. And digital, really starts out as analog. The term "analog" came to be used for film only after digital cameras came out, and then used to mean "not digital". Digital cameras, really are signal processing devices, which capture an analog signal, then convert them to digital.

[Alan Davenport]

There is no technical reason why "digital" must contain only 0's and 1's. It could as easily contain 1's, 2's and 3's, or any other number base. However, what is important is that digital can only have certain discrete values -- a bit can contain a 0 or a 1, but nothing in between, such as 1/3.

Film is not limited to discrete quanta; a point on a negative can contain not only the exact values that correspond to the digital values 0, 1, 2 ... 255, but also any value in between. Film is analog.

Now that "crop factor" thing is just insanity rearing it ugly head...

[Helen Bach]

The image on a piece of film isn't an analogue of an image, it is itself an image. That, to me, is a defining property of film. The discrete/continuous argument appears to be irrelevant. Just my opinion, of course.

Best, Helen

[N Dhananjay]

You could build an argument for film actually being digital - any grain of silver is either on or off (0 or 1). In contrast, a pixel on a monitor can be a larger number of shades of grey (e.g., 256 shades of grey) - that is, of course, still a discrete number of values.
I hink the analog thing is just a carryover from vinyl versus CD days - if something is not digital, it must be analog. So, if digital photography is digital, film photography must be analog.
And so the tiger chases its tail...;-)
Cheers, DJ

[Robert A. Zeichner]

The use of the word analog to describe older technology in general was almost unheard of before the advent of digital technology. Digital became the new way to express certain values in such simple terms (those ones and zeros) that it made possible, recording and transmission of that simple data so we could later convert it back to something that closely resembled the original picture, sound, whatever. Exact copies of things digital could be made and so reproductions of the original were now possible without the degradation associated with the old ways.

Before the digital age, we almost never needed a label to describe phonograph records, photographs, written words, etc., we didn't seem to need the word analog. Now it appears we need it to contrast things that are relatively new (digital this or that) to the things that were.

Why analog? Something that is analogous is something that changes in ways very similar to other seemingly unrelated things. An example: Sound which is mechanical energy, wavelike in nature, can vary in frequency (pitch), amplitude (loudness) and phase. Those changes can be expressed as electrical values (appropriate since electronics are used to capture, record and reproduce sound) that follow every change in the original sound very closely. The electrical values are analogous to the original mechanical energy.

In photography we deal with light of different intensities and colors of different hues and saturations. All these things are what we perceive when we observe a subject in real life. Film is designed to capture these attributes in a constantly variable fashion. The intensity of the light will determine the density of the negative, which will in turn determine the tones reproduced on the final print (subject to our darkroom manipulations, of course). The negative density is analagous to the original subject.

We never needed to make mention of this before we had a new way (digital) to express these values.

[Stan. L-B]

Interesting thread, excellent answers.

[Helen Bach]

...

In photography we deal with light of different intensities and colors of different hues and saturations. All these things are what we perceive when we observe a subject in real life. Film is designed to capture these attributes in a constantly variable fashion. The intensity of the light will determine the density of the negative, which will in turn determine the tones reproduced on the final print (subject to our darkroom manipulations, of course). The negative density is analagous to the original subject.

...

Doesn't that just land you back to DJ's tail-chasing, because such an analysis could just as easily be used to prove that B&W film was digital? It is not continuous, it is discrete. Than you can debate whether your tail is chasing you, or you are chasing your tail. Is the thing on film a representation of the subject, or a representation of the final image?

All this seems completely remote from my concept of 'the image on film'. Film appears to have been called analogue for no better reason than it is not that which is commonly known as digital photography. The lame and lazy way. Defined by what it is not, rather than what it is. No thought necessary. But it is brief, and its meaning can be guessed at quite easily. Damn.

Best,
Helen

[Steve Kefford]

...You are right, film isn't analog, it is chemical. And digital, really starts out as analog....

<<of or pertaining to a mechanism that represents data by measurement of a continuous physical variable>>

The key is that digital measures discreetly, whilst film measures contiuously. Therefore, film is analog.

Steve

[Ken Lee]

Straight lines (digital), when examined under magnification, are seen to be composed of many short curves (analog). Curves, when examined closely, can be seen as a series of many short lines.

There is a Buddhist term: "dependent co-arising". It suggests that in Nature, qualities define one other, and never appear alone. Tall and short, hot and cold, up and down, etc. are relative to one another. The same is true of analog and digital.

There is no such thing as a point, and no such thing as a line. Similarly, there is nothing that is purely analog or purely digital. Like points, lines, and curves, nobody has ever seen one - but they are helpful abstractions.

[Robert A. Zeichner]

Doesn't that just land you back to DJ's tail-chasing, because such an analysis could just as easily be used to prove that B&W film was digital? It is not continuous, it is discrete. Than you can debate whether your tail is chasing you, or you are chasing your tail. Is the thing on film a representation of the subject, or a representation of the final image?

The grain stucture of film might seem to be a case for classifying it as digital, but in most photography, grain is not terribly visible until very large magnifications are made in printing or if we examine the negative under high magnification. Where does one stop and differentiate between something that appears to be continuous and that which has some particulate structure. Is everything digital because matter is made up of atoms or further, sub-atomic particles?

It seems to me that the concept of digital technology as it relates to photography, relies on sampling things that are continuous (or appear that way to us) and expressing them with a quanitity of data that is far less than needed when using traditional, analogous methods of recording and transmitting that information. This, for the purpose of data economy, the thing that makes it possible for me to sit here, write this stuff and then send it out to the LF world via a very bandwidth-limited twisted pair of copper wires.

I suppose that one could also argue that when sampling rates approach enough times more than highest frequency of a particular sound as an example, then the data needed to express that sound digitally could exceed what's needed to record it with an analogous method. Is that the point at which digital reverts back to analog?

And while we are at it, how many angels can dance on the head of a pin?

[BrianShaw]

And while we are at it, how many angels can dance on the head of a pin?

It depends... are you referring to traditional analogue angels, or the 'new and improved' digital angels?

[Bill_1856]

Calling traditional film photography "Analog" is purely a sign of ignorance, and irritates me when I see it used that way. But I guess that I'll get used to it.

[Dave_B]

The term analog in photography is scale dependent and somewhat arbitrary but it is a convenient shorthand way of speaking. For example, whether we call film analog depends on how closely we look at our negatives. At the atomic level, single atoms are either chemically bonded in a certain way or not. A photon has hit it and created a certain chemical reaction or not. Atoms are digital, on or off. However once one starts to get collections of atoms in a grain or across a sheet of film then one can have a gray scale response that has very fine levels of resolution. You can have two sheets of film that each have 10 to the twentieth power numbers of silver atoms on them and one sheet can in principle have one more atom transformed by a photon than the other one.

The term digital usually gets used to describe systems that have a finite (and small) number of allowed values and analog systems those that have an infinite (or very large) number of allowed values. A digital camera has an analog to digital converter that takes the numbers of electrons generated in the CCD and sorts them into a certain limited number of output bins, like 8 or 16 bits. An 8 bit D-A can only have 256 allowed output values. However, film can in principle have two images that differ in intensity by only one part in ten to the twentieth power-a pretty fine scale that is many orders of magnitude finer resolution than a CCD and an A-D converter. I think that is why we call film "analog" and CCD based imaging "digital". Now if we convert the film to a digital image by digitizing the nearly infinite numbers of allowed intensity values and lump them into a finite number of bins, we have digitized it. The file is no longer analog. By doing this we have files that our computers can work with but clearly have lost a lot of the original information captured by the analog piece of film.

So the use of digital and analog is somewhat sloppy, because everything is digital at some level because quantum mechanics is the correct microscopic theory for how the universe works and things like photons and electrons are quanitized. However ten to the twentieth power is sufficiently close to infinity in comparison to 256 that we can use analog as a convenient shorthand for the latter and digital for the former kinds of imaging systems.
Cheers,
Dave B.

[Sal Santamaura]

Debate over "digital" vs. "analog" will achieve nothing. Marketers succeeded in convincing the public that "digital" is sexy. Those who lamented the move away from traditional methods adopted "analog" in resistance, probably hoping to benefit from the cachet it bestows in audiophile circles, e.g. tube amplifiers and vinyl records. APUG's very name is built around "analog."

As one who prefers silver-based black and white photography, I try to make young people aware of what they are missing. Rather than seeking an equally sexy term to counter "digital," I simply take away the marketers' weapon. The words I use are "chemical" and "electronic" imaging. Neither one sexy.

Among those non-snapshooting photographers who've grown up knowing nothing but electronic imaging, chemical imaging seems almost universally embraced. Sure, they captiulate to market forces and conduct their commercial workflow electronically, but are enthusiastic about the traditional approach for their personal projects.

In my opinion, marketing is about the illusion of choice. Many so-called choices all essentially the same. While currently available electronic cameras differ somewhat from each other, as a group the results they produce are far removed from what film cameras can provide. Perpetuation of chemical imaging is about real choice.

[tim atherton]

Apart from the slightly varied available definitions of the term analog/analogue (interestingly non of my dictionaries show the "electronic" use as the primary use of the word - even the fairly recent ones - though no doubt that will change), I think it's use in photography predates the "digital" camera and goes back to the wild days of the 1970's and the advent of the "digital" watch. Of course, it was digital because it used digits... opponents and watch nuts chose the classy word "analogue" to counter this Visigoth invasion of their timepiece gentle world.

I think photography just picked picked up on this (remember how electronic cameras had "digital" displays even though they weren't digital cameras...) and slowly adapted the terminology as convenient

which, of course, is generally how language works. (we all know how over time a term can easily come to have the absolute opposite meaning of it's original use - no right or wrong about it - just the way it works)

[Marko]

So the use of digital and analog is somewhat sloppy, because everything is digital at some level because quantum mechanics is the correct microscopic theory for how the universe works and things like photons and electrons are quanitized. However ten to the twentieth power is sufficiently close to infinity in comparison to 256 that we can use analog as a convenient shorthand for the latter and digital for the former kinds of imaging systems.

Except that those 256 levels are measured per each channel of the three for an 8-bit RGB file. And except that if we were only limited to 8-bit files, we wouldn't be having this discussion, at least not seriously.

But we are not limited to 8-bit files, so we mostly use 16-bits per channel, which gives as 2 to the power of 16 instead, or 65536 discrete levels of information, again per channel.

Then there is also the fact that channels do not add up, they multiply, so a 16-bit file is in reality a 48-bit file. That's 2^48 as the number of discrete levels of information, aka shades of color. I think that the resulting number is sufficiently close to infinity compared to 256 as well.

I wonder if there are any independent measurements of real-world film grain limitations in this respect?

[roteague]

Calling traditional film photography "Analog" is purely a sign of ignorance, and irritates me when I see it used that way. But I guess that I'll get used to it.

The same way I get irritated by the term "digital darkroom".

[Marko]

Apart from the slightly varied available definitions of the term analog/analogue (interestingly non of my dictionaries show the "electronic" use as the primary use of the word - even the fairly recent ones - though no doubt that will change), I think it's use in photography predates the "digital" camera and goes back to the wild days of the 1970's and the advent of the "digital" watch. Of course, it was digital because it used digits... opponents and watch nuts chose the classy word "analogue" to counter this Visigoth invasion of their timepiece gentle world.

I think photography just picked picked up on this (remember how electronic cameras had "digital" displays even though they weren't digital cameras...) and slowly adapted the terminology as convenient

This is an excellent analogy :)

Isn't it interesting that today the great majority of watches are electronic inside but still use the old-style hands display?

The language is, in the end, just a reflection of the way the brain works and that's why we will continue to have both digital watches and digital darkrooms.

[Scott Knowles]

It's used as the opposite to digital, and in many inappropriate ways. Why is an old style mechnical watch analog? It's like a cross over from the music industry which did use the distinction between analog tape and digital tape recording, mastering and producing. It applies to the recording of the original signal (or image) in a nondigital format. It's inappropriate for film, except one could argue the color is translated by the film's characteristics than being the original signal/image, and is, in that way, an analog conversion and recording. But still I'll vote against its use for film.

[roteague]

The language is, in the end, just a reflection of the way the brain works and that's why we will continue to have both digital watches and digital darkrooms.

The same reason people now call their cars "rides".

[tim atherton]

Why is an old style mechnical watch analog?

I believe it's because watches are an of analogue of passing time. i.e. the movement of the hands is an analogue of the movement of the sun (or the movement of the earth depending on where you stand...) etc

(this is analogue used in its main meaning, not the narrower secondary technical/electronic sense)

[Doug Kerr]

Hi, Bob,


So as I read more and more threads on this site I keep reading the term Analog in reference to Film.. . .
Film is not electronic in nature but rather chemical so I do not understand why someone would use Analog?

An analog representation is one in which some continuously variable physical property varies with, and thus represents, the value of another continuously variable property. For example, in a mercury thermometer, the height of the mercury column (a continuously variable phyiscal property) varies with, and thus represents, the temperature (a continuously variable phyiscal property). The one property is the analog of the other (thus the name). A mercury thermomenter is an analog instrument.

In an audio waveform, the instantaneous voltage on the circuit (a continuously variable phyisical property) varies with, and thus represents, the instantaneous pressure of the acoustic wave (sound wave). The waveform is an analog representation of the acoustic waveform.

By "continously-variable property" we mean a property that can take on any value over its allowable range. For example, the instantaneous voltage on an audio circuit at some instant, stated to to a precision of 18 decimal places, can be 0.200000000000000000 volts, or 0.200100000000000000 volts, or 0.200100000000000001 volts, all of which are different. And in fact it can be 0.200100000000000001000000000000001 volts, or any other value we can imagine (over the allowable range). We may not be able to distinguish them by practical measurement, but that doesn't change the fact that they are distinct.

By contrast, in a basic digital representation of an acoustic wave, a number represents the instantaneous pressure of the acoustic wave at a particular instant.

Now, to your question: in conventional negative photography, the density of the negative at a spot (a continuously variable physical property) varies (for a given lens aperture and exposure time) varies with, and thus represents, the luminance (brightness) of the corresponding spot on the scene (a continuously variable physical property). Thus a photographic negative is an analog representation of the luminance of the scene.

[George Kara]

Digital/Digitizing when used as a verb or adverb describes a sampling of wave amplitude using a binary unit of measurement. The "digital" in digital watch is used as an adjective modifying the noun "watch". The term "digital watch" holds no more meaning as a description than "shiny watch". There are all sorts of digital watches that are not only numeric.

To digitize an input or output is always a conversion to a finite binary unit of measurement. In other words the verb or adverb shouldn't be confused with the adjective.

When the doctor gives you a "digital rectal exam" the word digital is being used as an adjective. He/She most certainly won't be putting a camera up your ass. That may happen on the next visit. For this next exam your doctor may digitally photography your prostate. Perhaps if the doc is interested in astronomy he/she may also digitally photography Uranus!

In the proctologist office, separating your adjectives, verbs and adverbs may be significant.

George

[Marko]

The same reason people now call their cars "rides".

I prefer to think of it as the same reason they still call their image-taking devices "rooms (http://en.wikipedia.org/wiki/Camera_obscura)", a thousand years later, give or take.

;)

[roteague]

I prefer to think of it as the same reason they still call their image-taking devices "rooms (http://en.wikipedia.org/wiki/Camera_obscura)", a thousand years later, give or take.

;)


Yea, I suspect we won't even be able to understand the language spoken in a thousand years, just like we have trouble understanding the King James english today. ;)

[Marko]

Yea, I suspect we won't even be able to understand the language spoken in a thousand years, just like we have trouble understanding the King James english today. ;)

Probably not - a thousand years ago, English as we know it was non-existant and the Lingua Franca was Latin. Who knows which is it going to be in yet another thousand years... Chinese, maybe?

But in all fairness, I wouldn't blame our failure to understand each other on the language. ;)

[Dave Parker]

But I guess that I'll get used to it.

Well at least you admit there is hope!

LOL

:)

[David A. Goldfarb]

I don't usually use the term "analog" myself to describe traditional photographic processes.

As far as "APUG" goes, well, I wish it were called something else, but at least APUG is easier to pronounce than TPUG, FPUG, GSPUG, GSPTPDPUG, EtcPUG.

[Dave Parker]

As far as "APUG" goes, well, I wish it were called something else,

And all he said was "Hmmmmmm!"

LOL

:D

[tim atherton]

As far as "APUG" goes, well, I wish it were called something else, but at least APUG is easier to pronounce than TPUG, FPUG, GSPUG, GSPTPDPUG, EtcPUG.

the A stands for Analog?

[Marko]

the A stands for Analog?

I thought it was an indefinite article... :D

[Dan Ingram]

I call film "film." I've called it that for so long I think I'll stick with it. I do have a friend that refers to it now as "emulsion." I think that's silly, but then again I'm still using film, so who am I to say what's silly? As for analog, it stills makes me think of the old science fiction magazine of that name. Analog=science fiction? Hmmm -- I think I'll go shoot some "film."

Dan Ingram

[walter23]

Film is not electronic in nature but rather chemical so I do not understand why someone would use Analog?

Photochemistry is an electronic process (reduction of silver salts). And it's not digital (binary).

[kjsphotography]

Calling traditional film photography "Analog" is purely a sign of ignorance, and irritates me when I see it used that way. But I guess that I'll get used to it.

What is even more ignorant and irritating is digital users calling their work traditional and trying to pass it off as such.

[naturephoto1]

Unless, mistaken, Analog was first used for music where vinyl (and the original master tapes) was referred to analog soon after the introduction of digital which included CD and Digital recording and tape machines. During this period, there were also Direct to Disk vinyl recordings made as well.

Film photography was then equated with vinyl (records) in comparison with digital which was binary whether it was used for music CDs or for digital recording of the images.

Rich

[Struan Gray]

There has been a distinction in electronics between analogue (where the voltage level always means something) and digital (where, crudely, the voltage level only has to be above or below a threshold) since at least the 1940s, and probably before that. In the early days of computing, there were analogue computers, with circuits hard wired to solve a particular problem or equation.

Digital watches were called 'digital' because they counted discrete oscillations rather than slowly running down a battery in a controlled way. The essence lies in the idea of discreteness or countabillity. Or as your old English teacher would tell you, between less and fewer, some and many.

[David A. Goldfarb]

I remember "digital" watches and clocks being called "digital," because they displayed the time in numbers instead of requiring the ability to tell time.

[tim atherton]

I remember "digital" watches and clocks being called "digital," because they displayed the time in numbers instead of requiring the ability to tell time.

I know, the techies and manufacturers may have called them digital because they counted discrete oscillations, but only the ones with flashing number were called digital. Electronic watches with quartz crystals were still considered analog. It's the joy of the language that it twisted the term to a more obvious use I think...

[Struan Gray]

True David. I think both happened at the same time. 'Digital' counter-timer circuits with hot-filment number displays were a common novelty in post-war laboratories. They existed before then, but it was the post war surplus boom that put them in the hands of regular lab people.

A purist would note that when you feed an analogue signal to a display with discrete numbers on it you are digitising it in the discretisation sense in the display control electronics, even if the clock supplying the timing signal is analogue. I doesn't hurt the marketing that both senses of the word 'digital' are satisfied at once.

The UK railways now have digital analogue clocks, where the second hand sweeps smoothly, but the minute hand lurches forward with an audible clunk. Given the state of the trains and the timetabling, it's an appropriate dogs-dinner approach to the problem.

[Ralph Barker]

. . . The UK railways now have digital analogue clocks . . .

Interesting. I would have thought the UK railway clocks would have moved only after the train arrived, so the train would always be "on time". ;)

[Marko]

Struan,

At least they appear to have a thoughtful if not quite thought-out approach to the problem. Not to mention that they do realize it is a problem, of course. :) I remember the time when there was no problem with timetables, or at least nobody recognized it as such, but that's only the sign of how the times change regardless of the schedule.

As for analog and digital - the easiest way to visualize the comparison would be using an oscilloscope. An analog signal will show as a smooth curve while a digital signal will show a curve comprising of a lot of small steps.

It is in essence an issue of sampling. Any electrical signal, or to be more precise, any electromagnetic signal is discrete by nature, but the individual discrete steps are so small - i.e. the sample rate is so much finer than our ability to resolve the individual steps - that we see it as continuous spectrum.

Musical CD became mainstream the moment the sampling rate became so much better than our ability to detect the individual steps that most of us could not perceive the difference any more. Given that it was easier to maintain, harder to damage and cheaper to produce, it was only a matter of saturating the market with reproduction devices. That happened in the early 1980's and today, the phrase "skipping like a broken record" makes no sense to most anybody born after 1980.

Well, the first years of this century seem to be photography's 1980's, as the sensors have approached the level of imperceptible sampling steps at "standard" magnifications and viewing distances and the market saturation has obviously happened at the consumer level as well as small format professional levels, and it is now happening in high-end medium format level.

Speaking of terms, what represents "standard" and "imperceptible" may be arguable, but I think it is obvious that they follow the classic distribution curve, with the top portion representing the majority the target population.

As for "analog", "traditional" and such - if a name absolutely must be given to it, I prefer to simply use the terms "film" for the medium and "chemical" for the process. They still provide a clear technical description but are not loaded with ideological concerns. "Analog" is basically a nonsense, as even the most ardent film fans seem to begin to realize, while "traditional" is very obviously a shifting target. What was traditional yesterday is considered "alternative" or even "historic" today, and what is traditional today is in the process of such transition as we speak.

[Emmanuel BIGLER]

I also refuse to speak about "analog vs digital" in photography.

To me the battle is silicon (as a spatially sampled photodetector) against photochemistry.


Photochemistry rules in terms of lateral resolution : think about 0.1 microns linewidth pattern in a photoresist. No photochemistry, no silicon technology !
Now that silicon can be sampled with a sufficiently fine grid with many pixels, silicon rules in terms of detection efficiency : about 1&#37; for best films vs. 15%, for example in the KAF-39000 Kodak "645-sized" sensor. (OFF-TOPIC here of course ! )

And, for sure, digitizing things for post-processing is nice but is not proper to silicon. Film can be digitized as well !
Digital enlargements or prints vs. analogue enlargements or prints, however, do make sense to me.

From Robert A. Zeichner:
The use of the word analog to describe older technology in general was almost unheard of before the advent of digital technology.
See below the remark by Struan Gray about the good old days of analogue calculators.

From Struan :
In the early days of computing, there were analogue computers, with circuits hard wired to solve a particular problem or equation.

Since we love top class lenses here, it is worth mentioning that such a dedicated analogue computer was in use at Institut d'Optique in Paris just after WW-II for lens design and optimization. An image of the beast can be found in the classical textbook by Fran&#231;on & Mar&#233;chal 'Diffraction, structure des images' (Masson, ed. 1970, out of print for a long time now !)
In order to compute an integral, you could do it by analogue means with a mechanisms made of cams and various "roulettes" and analogue counters ;-)
After that there has been an era of analogue computers without mechanical parts, only operational amplifiers, they were good at solving differential equations.

From Marko
Isn't it interesting that today the great majority of watches are electronic inside but still use the old-style hands display?

Living in the heart of the watchmaking country, my 0,02 euro about a watch being analog or digital.

Conventional mechanical wrist-watches cannot display intervals of time
shorter than half the period of the oscillator. So actually if you look a the movement of the second hand with a good loupe, is is not analogue, it is "quanticized" ;-)

Many modern mechanical wrist-watches have a 3 or 4 hertz oscillator. But the figure is too small an does notfeel 'rich' enough in the quartz era (f=32768 Hz), so "they" refer as : 21600 or 28800 alternances per hour ;-) the quantum is the alternance i.e. half the period. Same for good old clocks with a pendulum length of about one metre and a period of about two seconds, one alternance, one second. Exactly the quantum in a quartz watch be it of analogue display or digital display, the stepping motor rotates 1/2 turn each second, 2 seconds per 360&#176; turn ;-)

However, the last "spring-drive" Seiko electro-mechanical movement is closer to a true analogue machinery.
A spring-driven electrical generator rotates at a certain frequency and this frequency is synchronised to the frequency of a quartz oscillator by a feed-back system acting as an adjustable brake. So the second hand does not jump at all. The display is really analogue ! Note that the source of energy is an oscillating mass that tensions a barrel spring like in any classical automatic watch. But there is no anchor escapement at all, no digital counter to generate the 1Hz frequency, no stepping motor.

[Michael Graves]

So as I read more and more threads on this site I keep reading the term Analog in reference to Film. I am very confused by this as I am an IT Professional and Analog is the opposite of Digital (1's and 0's) only in the sense of data transmission or capture. Like how a Vinyl record has continously changing quantities (bumps in the grooves) and a CD is an organized collection of 1's and 0's.

Film is not electronic in nature but rather chemical so I do not understand why someone would use Analog?

I'm sure there are other words that are inherently confusing as it seems to be a trend in photography lately, such as crop factor :)

Even from an IT standpoint, a photographic image can be considered analog. Nowhere in the literature that I've read does it state that analog is specific to any particular data source. The origin of the "analog" signal from your LP records that you convert to digital is the grooves in the record and not the electronic signal that is generated by the conversion technology. Likewise the "analog" signal from the photograph is the range of electromagnetic wavelengths that are reflected from the surface of the paper. Both the LP and the photo eventually have to be converted to electrical signals prior to digitizing.

[Ken Lee]

It is in essence an issue of sampling. Any electrical signal, or to be more precise, any electromagnetic signal is discrete by nature, but the individual discrete steps are so small - i.e. the sample rate is so much finer than our ability to resolve the individual steps - that we see it as continuous spectrum.



http://www.kenleegallery.com/images/forum/emerson.gif

Perhaps I am in over my head here, but don't concepts like the Wave/Particle Duality and Heisenberg's Uncertainty Principle suggest that neither discrete nor continuous measurements can ever be perfectly obtained ?

The edges of the steps can never be made perfectly sharp, nor can they be said to be round. Under magnification, aren't they revealed to be neither discrete nor continuous ?

[Terence McDonagh]

I prefer the term "unplugged". Sounds more rock-and-roll. But then, none of my cameras use a battery of any sort. I don't even tend to use a light meter.

[Marko]

http://www.kenleegallery.com/images/forum/emerson.gif

Perhaps I am in over my head here, but don't concepts like the Wave/Particle Duality and Heisenberg's Uncertainty Principle suggest that neither discrete nor continuous measurements can ever be perfectly obtained ?

The edges of the steps can never be made perfectly sharp, nor can they be said to be round. Under magnification, aren't they revealed to be neither discrete nor continuous ?

Hey, I never mentioned "perfect"!

I think we can safely agree that all the quantum stuff is way too fine grained for the fat we're all collectively chewing here. But speaking of, there are cynics who would say that the Uncertainty Principle was simpy Heisenberg's way of admitting that even his perception of physics was not limitless... :D

Changing the topic here, I like the stairway image. Or am I? :) Either way, why don't you post a bigger version?

[Ken Lee]

The stairway image is an old Platinum print by Peter Henry Emerson - I believe it is Wells Cathedral in England, and the photo is named "Sea of Steps". This photo is the only one I could find on the web in a quick search. I have seen an original, and it is a real gem.

According to www.leegallery.com (http://http://www.leegallery.com):

"The English photographer, P. H. Emerson was a major influence in late nineteenth-century photography. A champion of a "naturalistic" aesthetic Emerson fought to have photography recognized as an art form in its own right. He rebelled against the "high art" photography of the day that was typified by the work of H.P. Robinson and O.G. Rejlander. Emerson found this work to be sentimental and artificial. At a time when many photographers were struggling to imitate painting and painterly styles, Emerson devised his own standard for photography stressing natural settings and spontaneous poses. He also believed in focusing sharply only on the central object of a scene and allowing the rest to be slightly blurred. He believed this to be closer to the way the eye sees, rather than sharp on all planes as a camera lens can "see".

He bought his first camera in 1882 and spent the next several years studying and experimenting in photography. By 1885 he was exhibiting his work and winning prizes widely. In 1889 Emerson published Naturalistic Photography a handbook detailing his approach and the theories he believed supported it. Although he did not publish or exhibit his work after 1900, Emerson's influence on photography was profound. He is often called the father of art photography and supported and recognized talent in other photographers. Alfred Stieglitz was first recognized by Emerson, who awarded him first prize in a competition. He also produced a book on Julia Margaret Cameron who was widely regarded as a photographic crank by many of her contemporaries.

Life and Landscape on the Norfolk Broads a book containing 40 platinum prints was published in 1886. He subsequently published several more books that reproduced his photographs in high quality photogravure. Influenced by the arts and crafts movement, and in response to the industrial revolution, he frequently photographed farmers and fisherman at work practicing old trades and crafts that were rapidly becoming outdated. His landscapes recall a simpler time before the industrial revolution."

[David A. Goldfarb]

The famous image of the "Sea of Steps" in Wells Cathedral is by Frederick Evans--

http://www.moma.org/collection/browse_results.php?criteria=O&#37;3AAD%3AE%3A1774&page_number=1&template_id=1&sort_order=1

I found myself in Wells Cathedral once and photographed the steps with the sign now displayed in the lower left hand corner along the lines of, "Caution: Extremely Worn Steps!" I called it "The Sea of Steps in the Age of Liability." I printed it up as a postcard, but I think I have a scan somewhere.

[tim atherton]

The stairway image is an old Platinum print by Peter Henry Emerson - I believe it is Wells Cathedral in England, and the photo is named "Sea of Steps". This photo is the only one I could find on the web in a quick search. I have seen an original, and it is a real gem.


Frederick Evans

[tim atherton]

http://www.moma.org/images/collection/FullSizes/20113004.jpg

[Ken Lee]

Oh yes. That's it !

Evans, not Emerson.... Pardon my confusion.

Here's an image by Emerson:


http://www.kenleegallery.com/images/forum/emerson2.jpg

[artedetimo]

To jump in after the fact:

I use the terms silver, non-silver, and digital to refer to the capture sensor. All sensors are "digital" in the sense that they are generating what amounts to a histogram of photons hitting spots on the sensor. Sure they travel as waves, but they are particles when they strike a sensor, and that is what is tallied. Whether we are actually creating digits of those tallies with a computer or not is irrelevant.

After that, whatever the process for turning photon tallies into images, you end up with a photograph which is definitive in nature. Anything in between is just recipe. Just like there are a million ways to cook a duck, there are many ways to go from capture histograms to photograph. Lump them how you will but the results are all cooked ducks :)

[Struan Gray]

Interesting. I would have thought the UK railway clocks would have moved only after the train arrived, so the train would always be "on time". ;)

They have changed the definition of 'on time'. The clock is only there to give you hope, in a momento mori sort of way.

Emmanuel: love the tidbits.

Baby physicists are sometimes taught that Heisenberg's uncertainty principle is just another example of what happens if you try to mimic a sharp change with smooth waves: with the right assumptions it drops out of the wave equations unbidden. To me, that's like saying the length you measure in inches with an imperial yardstick is the same as the one calculated in millimeters by the laser interferometer. It ignores the fundamental nature of 'length', as well as the specific qualities of the individual measuring devices.

It is still an open question if space and time are truly quantised, in the sense that charge comes in discrete chunks if you look closely enough. One problem is that a proper digital description of the world *and* a proper analogue or continuous description of the world are both what mathematicians call 'complete'. You can describe anything with either of them if you work hard enough. The only thing constrained by the tools is the thinking of the person using them.

Digital photographs are different from digital clocks in one important way. Time, as a one-dimensional number, only needs to be sampled. A scene to be photographed needs to be both sampled and quantised: i.e. you need to define pixels, and fill them with values. The tradeoffs start to mix when you get down to the fine detail, just as grain muddies both tonality and resolution on a piece of film, but in principle you have two axes of quality to worry about.

A final nit: silver emulsions are not digital, even the Black and White ones. True, a grain is either developed or it is not, but the shape of the resulting silver speck admits an infinity of possibilities. Film photography is continuous, even if it is not analogue.

[Michael Alpert]

There seem to be two components to the definition of analog as used in photography: (1) "Correspondence in some respects between things otherwise dissimilar," and (2) "Data presented or collected in continuous form, as temperature variation or voltage measurement." Integrating these two components, one can say that a film-based photograph is Analog (or, more accurately, an analog) in that it is a direct optical representation of a specific subject which is in continuous (i.e., non-digitized) form.

[Marko]

Be that all as it may, I am quite certain that if I had a cat, it would still be a cat even if I named it Heisenberg instead of Schr&#246;dinger...

:D

[Michael Alpert]

Marko,

Are you responding to my post of a few minues ago? If so, I don't understand what you are objecting to. If the name doesn't matter to you, why object to Analog (which, come to think of it, might be a great name for a cat!).

[Marko]

Michael,

No, we just happened to post at roughly the same time. That was just a (lame) physics joke.

As for the name, if I really had a cat, I think I would name it Pixel.

:D

P.S.

Sorry, I am really in the joking mood this morning, so don't take me too seriously. I am a dog person, after all.

[Andy Eads]

Film based photography captures the image by a stochastic process. It is not digital. The image is an analog of the original scene. Digital photography uses an analog detector which is fed to an analog to digital converter (ADC). An ADC quantitizes the image into a number of discrete levels coresponding to the output of the detector. These numbers are stored for later editing, printing or display. I can view film directly, therefore it is a proper analog of the original scene. I can hold a memory card in front of my eyes and see nothing except a small flat piece of plastic. To be sure, both forms of the image are real enough. One is analog the other digital.

[Marko]

Film based photography captures the image by a stochastic process. It is not digital. The image is an analog of the original scene. Digital photography uses an analog detector which is fed to an analog to digital converter (ADC). An ADC quantitizes the image into a number of discrete levels coresponding to the output of the detector. These numbers are stored for later editing, printing or display. I can view film directly, therefore it is a proper analog of the original scene. I can hold a memory card in front of my eyes and see nothing except a small flat piece of plastic. To be sure, both forms of the image are real enough. One is analog the other digital.

That's interesting... Whenever I tried to view film directly, I saw nothing. Then someone told me it had to be developed (processed) first...

:D

[Alan Davenport]

Earlier, a couple of posters equated grains in the film emulsion, with digital pixels. That analogy :eek: fails on a couple of fronts: First, film grains are not simply "on" or "off;" grains change size, shape and density with exposure, development, etc. Also, unless the film emulsion is so thin that it becomes literally just one grain thick, there will be overlapping grains at various depths through the emulsion; light transmitted through that emulsion will be affected by different grains in different amounts. The result is that the light passing through any point on the film can have any of an infinite range of intensities upon exiting the emulsion.

Digital signals can only take on rigorously defined, discrete values within their range. A stairway has a definite set of elevation changes as you go up or down. You can stand on one tread at a particular height, or go up or down a set amount and stand at the next height, but you can't stand between the set positions of the stair treads.

Analog signals are continuously variable, and can have any conceivable value between the function's minimum and maximum. The comparison to our digital stairway would be a smoothly sloping ramp. The person on the ramp can stop at any height along the way; there are an infinite number of elevation values available.

So, because film can have an infinite number of tones between maximum and minimum, and thus is continuously variable over its range, we choose to call film "analog." It wasn't necessary to use the term "analog" before digital photography came along, but film was then, and is now, storing an analog signal. Film is analog, and that is a correct and accurate use of the term.


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Here are a few definitions of analog (thanks to Google!) from the web:

* Continuous and variable ... waves that represent an infinite number of values. Opposite of analog is digital.
http://largebande.gc.ca/pub/technologies/bbdictionary.html

* Continuously variable signals or data.
http://www.incredible.co.za/services/glossary/glossary.asp

* refers to a type of measurement in which the "line of measure" is continuous as compared to one which is discretely incremented.
http://www.notepage.net/wireless-messaging-glossary.htm

* A signal that can take on any value in a range. Contrast with Digital.
http://allinternetnow.com/allnow/ain_terms.htm

* Continuously changing, rather than jumping from one numerical value to the next. See digital.
http://www.mumbaicyber.com/glossary_com_hardware_micro.asp

* A signal that represents continuously variable information.
http://www.florite.com/support/terminology.htm

* A type of signal ... that takes on a continuous range of values.
http://www.zetex.com/12.0/12-1-3.asp

* Pertaining to measurements or devices in which the output varies continuously. Compare to digital.
http://www.novalynx.com/glossary.html

* An analog or analogue signal is any continuously variable signal. It differs from a digital signal in that small fluctuations in the signal are meaningful. Analog is usually thought of in an electrical context, however mechanical, pneumatic, hydraulic, and other systems may also use analog signals.
http://en.wikipedia.org/wiki/Analog_(signal)

[Gordon Moat]

Marko,

Are you responding to my post of a few minues ago? If so, I don't understand what you are objecting to. If the name doesn't matter to you, why object to Analog (which, come to think of it, might be a great name for a cat!).

Analog seems more like something the cat would leave in the litterbox.:D

[Marko]

Analog seems more like something the cat would leave in the litterbox.:D

Yeah, what with all that grain... :D

[Gene McCluney]

Well, I'm convinced. I am now going to call my film-based photography "Lincoln-Log Photography" rather than Ana-Log Photography.

[artedetimo]

To the quasi-science prone (or jargon prone if you are scientists): are biological eyes digital or analog? Waves hitting chemical receptors generating on or off impulses. Sounds digital to me...

[Struan Gray]

To the quasi-science prone (or jargon prone if you are scientists): are biological eyes digital or analog? Waves hitting chemical receptors generating on or off impulses. Sounds digital to me...

Most biological sensors give out a pulse-density modulated digital signal. I think eyes are no exception.