Wow - read this re: Film versus Digital debate!

[rowland_mowrey]

Daniel, Mark;

 

First off, silver is not black. Spectrophotometric curves easily show that it comes in a variety of "colors" from reddish

to blue black. This is, of course demonstrable by preparing colloids of silver in varying colors.

 

Now, the electron micrograph above is developed silver! That is fact, and many other electron micrographs exist to

show the same thing as the ones above show. Silver is analog. An easy way to demonstrate this is to draw a line

on paper with a pencil very lightly. Repeat doing it harder to get a denser line. This appears to be digital, but the

density gradient is analog. Magnification of this graphite deposit shows that it is made up of tiny dots of abraded

graphite on the paper. The combination of the visual impact is either digital or analog depending on the way you view

it or maybe we should say the magnification.

 

An even better example is the resistor. We would all agree that a resistor is an analog device but at the atomic level

it may appear to be digital if we consider individual electrons. A variable resistor produces an analog signal that can

be measured by a voltmeter, but an electron count can show its digital nature. This is Einsteinan physics (macro) vs

Quantum physics (atomic) scale in a way. That might be a rough analogy.

 

Now an electronic D/A converter does not produce a smooth gradient, it produces a jagged gradient, but film

produces a smooth gradient. An A/D converter changes film images into a smoother gradient than a D/D image is

possible of producing.

 

So, silver deposits in film can be shown to be having a smooth gradient with all possible tones from Dmin to Dmax,

but a digital image cannot be.

 

I'm adding #9 to my post above.

 

9. All of the above will be ignored or dismissed or not really even read. The proof of this is that some of you cannot

even spell my name when you try to criticize my post.

 

Having analyzed both silver and digital output, in both image and electronic forms for many years, I find this thread

continues to be packed with misstatements and myth.

 

Now, on to the color aspect and the side by side nature of the pixels.

 

In digital, a sensor is of a given receptivity to color - R/G/B etc. Many schemes exist to form proper digital images.

In film, the color receptors - grains, are stacked and in most cases are transparent to wavelengths of light to which

they are not sensitive. Therefore a red light in a digital scene striking a green sensor does not cause exposure, but

with film it causes exposure in the layer underneath at the correct spot. The one causes aliasing and the other does

not. In digital imaging, aliasing is what causes moire patterns to appear in motion picture or in stills with fine lines.

 

Now if you think this is not a problem, many small objects represented on a sensor of any type can be on the order

of 1 micron. This is far smaller than most pixels in digital sensors, but can impact and cause imaging on silver

halide crystals. I have done the epxeriments to show this as many have in the industry. This tiny colored image can

vanish totally or create discontinuities in the image. A colored thread seems to appear and disappear as it passes

over a row of pixels whereas in film, it does not. This is another example of aliasing.

 

Now, I know you will ignore this or try to refute it somehow. All I can do is present the facts. Remember that on the

atomic scale you can prove that anything is digital. But, this does not mean that it is true. Sorry, but unless you

go into the lab and do some measurements yourself, your arguments are baseless.

 

BTW, it took years for them to go from the high contrast (on/off) digital nature of the early electronic sensors to those

of today. Early Xerox images were essentially totally digital, whereas today they represent the whole gamut of V/Log

E (Voltage vs Log Exposure) in a curve, but only as 8, 16, 32 or whatever... steps.

 

Ron Mowrey

[rishij]

Mark, you write:

 

Grains are photon counters, less photons and the lattice structure is less dense, more photons mean the lattice becomes potentially denser right up to the whole grain.

 

If that were the case, then when I take a new roll of film, and roll out the film, place it under a light for 10 minutes, shouldn't the entire thing turn black? Instead (I just tried it), it turns darker, but not that much darker. Just a tiny shade darker than the unexposed film next to it which I can see by rolling out the film a little more after holding it under a light for 10 minutes.

 

Now, you keep asking how, in that infamous image you first posted, is the outer rim of that triangle black, but not the inner core (which remains clear)? Here's one hypothesis: That's an entirely (mostly) exposed grain *prior* to development; the rest of the grain (inside) doesn't turn black because the outer rim is already metallic silver, so any more photons hitting it don't penetrate into the crystal to knock any more electrons off halides buried within the crystal, because the metallic silver (already reduced from exposure) around the edges of the grain are essentially blocking the light. Precisely why it becomes harder and harder to expose film the more you expose it, giving it that wonderful logarithmic response that keeps film from 'blowing out'. Now, when you develop this grain, it'll turn completely black.

 

Basically, what I'm saying is, with that hypothesis, the picture doesn't preferentially support *you* OR *Reichmann*. Either of you still could be correct; that picture, to me, proves neither one of you absolutely correct.

 

I think what we need to talk about is the chemistry of what happens.

 

Mark, despite touting your theory vehemently, you haven't address my fundamental questions regarding the kinetics of the chemistry that goes on in development. I quoted a Chem. Rev. paper that says: "In this way an invisible speck of a few silver atoms adheres to the surface of the silver halide crystal. This speck, composed of more than three atoms of silver, is a latent image site and serves as a conductor through which electrons are transferred from the developing agent to the entire silver halide crystal."

 

Let's say I buy your argument Mark. Then are you saying that the number of such specks of a few silver atoms (adhered to a sensitivity center) around the surface of the grain, in the end, determines the rate of the development reaction, and thus, the amount of silver atoms reduced within an individual grain? If so, what is the maximum number of tones representable by such a grain? Well, it'd depend upon the total number of sensitivity centers holding reduced silver atoms, wouldn't it? That is:

 

Let's say only 1 sensitivity center gets 3-4 silver atoms clustered around it. Arbitrarily, I'll say that that means, upon development, only 1/100 of the grain is reduced to black metallic silver.

 

Now let's say 2 sensitivity centers gets 3-4 silver atoms clustered around it. When developed, let's say 1/50 of the grain is reduced to black metallic silver.

 

Now let's say 10 sensitivity centers gets 3-4 silver atoms clustered around it. When developed, let's say 1/10 of the grain is reduced to black metallic silver.

 

Do you see what I'm getting at here? Basically, the final 'blackness' of the grain must be determined by the number of sites on a given crystal that have at least 3-4 silver atoms (reduced from photon exposure). And how many such sites are possible per grain will determine the number of tones possibly represented by a grain, according to your theory.

 

And I seriously doubt there are that many such possible sites on a grain, thereby reducing the number of tones possibly represented by your grain. I would argue that the number of tones representable by the clustering of fully developed (100% black) grains, within a layer, and across layers, would give you many more tones than the number of tones possible according to your theory.

 

Because, remember, your theory hinges upon the RATE OF THE CHEMICAL REACTION during development being controlled, very finely, by the number of initial sites & extent of reduced silver atoms. And I'm just not sure how fine tuned this chemical reaction is such that you can generate thousands of tones (thousands of different levels of *amount of reduced silver* within a grain) just by controlling the rate of the reduction reaction based on your initial conditions of how many reduced silver atoms exist per grain. Chemical reactions proceed extremely fast at the atomic level!

 

Rishi

[photo_smith]

Rishi

Silver atoms do not come in your choice of any of one of millions of tones. Mark agrees.

Silver grains do not come in your choice of any of one of millions of tones. Mark disagrees.

 

 

I agree period and have consistently stated that silver ATOMs are black, where I disagree is that I believe that those

atoms form structures that pass light.

If they pass light in varying degrees they cannot be binary.

 

Rishi

Mark:

While I do wish for you to continue arguing your point, please try & present some new evidence for your argument,

because at this point you are just wasting time repeating yourself ad nauseam. And I don't mean that in an offensive

way; I'd just really like to see you present some new evidence that supports your case :)

 

Why do I need to present a 'new argument'?

 

Here is how film works.

 

Pairs of silver bromide ions are held together by an electrical charge. The silver ions are positively charged because they

lack one electron.

The bromide atoms are negatively charged because they have an extra electron.

Specks of silver sulphide, and some free ions complete the crystal structure.

 

When a photon of light strikes the crystal, it gives extra energy to the electron of the bromide ion allowing it to 'roam'

though the crystal, it then attracts and bonds to a positively charged free silver ion.

 

Specks of impurity (normally silver sulphide) attract this new bonding these are known as 'sensitivity specs'

 

As more photons hit the crystal more electrons are released, these and more silver ions migrate to the many sensitivity

specks.

This combination of ions creates silver metal which at this point is invisible (latent) so we need a developer to reduce the

latent silver to black silver.

The lattice structure created has a density directly proportional to the amount of photons that strike the grain, the denser

the filamentary structure the more photons have hit the grain.

 

These developed silver grains are like a wire wool pad light can pass through them, and it is the effect of many of these structures piled on top of each other that give the illusion of 'graininess' and tone which are optical effects.

 

I think I have proved my point, and have spent many months researching, I don't know why it so hard to accept the

above for some and they still cling to the belief that grain is either totally black or clear when the structures clearly

transmit light in proportion to their exposure/development

[patrick_mont]

Wow...I can't belive all of the posts on this forum! 151..mine will make 152

[benny_spinoza]

"People, I just want to say, you know, can we all get along? Can we get along?"....Rodney King, May 1, 1992.

[rishij]

Vijay & Mark,

<p>

You know what the biggest problem with your argument is?

<p>

Here:

<p>

<a href="http://findarticles.com/p/articles/mi_m1511/is_8_21/ai_63583781/print?tag=artBody;col1">This article</a> says: "There are 10 billion crystals in a frame of ordinary film--the equivalent of 20 million digital pixels."

<p>

I actually disagree and say it's more the equivalent of 10-12 million digital pixels. But I digress.

<p>

If there are 10 billion silver grains/crystals per 35mm frame, and if each one of those grains can represent thousands of tones, then <b>each one</b> of those grains would be the equivalent of a pixel. <b>Each one</b> of those grains could represent an image element. Which would then give you a 10 billion pixel image. But that's just ridiculous. C'mon. From many (fine, subjective) tests, we've seen that a 35mm frame of film really doesn't hold any more than 10-12 MP worth of information.

<p>

So let's start an intelligent argument here. Let's say that a frame of 10 billion grains gives you a 10 million pixel image. So, 10 billion/10 million = 100 grains that collectively make up an 'imaging element', or analog equivalent of a 'pixel', in film. Now, since there are 100 grains which can all either be black or clear (on or off), one could argue that there are a 2^100 tones that can be generated. I doubt that's true, since if exposure is such that 50 of those grains are black, while 50 are clear, I doubt it really matters WHICH 50 are black... from a distance (low magnification), it'll just look gray (50% black). So, let's say, in the worst case scenario, 100 tones can be represented by this cluster of 100 grains.

<p>

Before I proceed any further, is that reasonable? How many different tones do <i>you</i> think can be generated by a cluster of 100 grains?

<p>

Rishi

[rishij]

Ron:

 

"Now an electronic D/A converter does not produce a smooth gradient, it produces a jagged gradient, but film produces a smooth gradient. An A/D converter changes film images into a smoother gradient than a D/D image is possible of producing."

 

Huh? An A/D converter changes film into a smoother gradient than a D/D image is capable of producing because film itself has a smooth gradient? So you're arguing that the 'real world', or 'nature', that the digital camera is shooting is not as smooth as film??

 

The only manner in which your argument makes sense is if you're saying that interpolation from the Bayer pattern results in less smooth gradients (D/D), whereas the A/D conversion process on a scanner does not need a Bayer pattern, so therefore can give you smoother results. Which I agree with.

 

Is that what you meant?

 

Rishi

[bernardwest]

I'm loving this debate! I keep changing sides depending on whose answer I have just read. But I can't get past one inescapable truth as posted by Daniel: That at VISIBLE light levels and magnifications, a location on a negative is one of two states - either black or clear. There are no grey tones visible. Until someone explains how this inescapable FACT can be reconciled with the assertion that that a negative's tones are made up of tiny different toned areas, I'm going to have to believe what my eyes are telling me is true.

[photo_smith]

Rishi

 

If that were the case, then when I take a new roll of film, and roll out the film, place it under a light for 10 minutes,

shouldn't the entire thing turn black? Instead (I just tried it), it turns darker, but not that much darker. Just a tiny shade

darker than the unexposed film next to it which I can see by rolling out the film a little more after holding it under a light

for 10 minutes.

 

Eh? you do realise what latent means? and the fact it is changing at all shows you a reaction has taken place, as I

stated in my previous posts you need a developer to magnify the action.

 

Now, you keep asking how, in that infamous image you first posted, is the outer rim of that triangle black, but not the

inner core (which remains clear)? Here's one hypothesis: That's an entirely (mostly) exposed grain *prior* to

development; the rest of the grain (inside) doesn't turn black because the outer rim is already metallic silver, so any

more photons hitting it don't penetrate into the crystal to knock any more electrons off halides buried within the crystal,

because the metallic silver (already reduced from exposure) around the edges of the grain are essentially blocking the

light

 

That image is of developed silver as Ron points out above. So if grain is binary how can it be black and clear at the

same time?

 

And I seriously doubt there are that many such possible sites on a grain, thereby reducing the number of tones possibly

represented by your grain. I would argue that the number of tones representable by the clustering of fully developed

(100% black) grains, within a layer, and across layers, would give you many more tones than the number of tones

possible according to your theory.

 

Why do you doubt? Mees and James suggest there are many hundreds of thousands of sensitivity specks in each grain

what makes you think there are only a few?

 

Because, remember, your theory hinges upon the RATE OF THE CHEMICAL REACTION during development being

controlled, very finely, by the number of initial sites & extent of reduced silver atoms.

 

Yes and development is crucial, time temperature agitation all play their part if grains were only 1 state than only one

development time would be needed as the grains would just develop to completion.

 

In photography that stae exists with line (lith) negs, extreme contrast is possible because very high p.H > 11 developers

with high activity are used normally a formaldehyde-hydroquinone based developer is used which gains maxiumum

density very rapidly (often called infectious development) and a gamma of 10 is not unusaual, that is the closest film

gets to being binary as the whole point is to rapidly turn any exposed silver to metal.

 

Normal development is a slower affair with low energy low p.H <9 often using sodium metaborate (D76) this gives us

very fine control over tonal values, as can dilution with developers like Rodinal which give lower gamma and more tones

as the filamentary structures develop slowly and are more defined.

 

But honestly I can tell you are sceptical so [shrug] i'm going to bed, you should read Rons post above he is one of the

leading experts in the field and has 15 or so patents to his name, if he says film is analogue- you can take it as read.

[rishij]

Mark:

 

"As more photons hit the crystal more electrons are released, these and more silver ions migrate to the many sensitivity specks. This combination of ions creates silver metal which at this point is invisible (latent) so we need a developer to reduce the latent silver to black silver."

 

OK, I think we've uncovered a serious misunderstanding here.

 

'silver metal which at this point is invisible... we need a developer to reduce the latent silver to black silver.'

 

What? Uncharged Ag (0) is metallic silver. Which is black. It's not reduced any further to anything. Metallic silver is metallic silver. There is no 'latent silver' vs 'black silver'. What are you talking about??

 

The speck of metallic silver (charged 0) serves as an initiator site (catalyst) because it is CONDUCTIVE, which means it allows the developer molecule to channel electrons through this site to the silver IONS (charged +1) within the crystal that have not yet been reduced. This is a radical process that involves one electron abstractions/donations.

 

Please tell me you understand that.

 

And as for the posts about us 'getting along', we ARE getting along. This is a HEALTHY DEBATE, something that occurs all the time in science. It's necessary to arrive at an accepted conclusion. We don't hate or disrespect one another; we're just trying to collectively work this out. Please participate! For the sake of knowledge... this is very interesting & I really want to unequivocally come to a conclusion.

 

Rishi

[photo_smith]

Rishi

What? Uncharged Ag (0) is metallic silver. Which is black. It's not reduced any further to anything. Metallic silver is

metallic silver. There is no 'latent silver' vs 'black silver'. What are you talking about??

Well this is simple:

here is a quote from Michael Freemans 'Film technology'

The combination of silver ions creates silver metal, this is invisible and needs the action of a developer to make it

visible.

 

You cannot see a latent image it needs to be 'magnified' by the developer.

Possibly I should have stated convert to rather than reduce.

[rishij]

Mark or Ron:

 

Please explain to me why a 35mm frame of film doesn't give me a 10 gigapixel image, if each silver grain is capable of displaying the entire dynamic range of film.

 

And for the sake of science, I'm posting this review on the chemistry of color photography... if you're interested, please read it & see if you can come to a conclusion. I'm still chugging thru it.

 

http://staff.washington.edu/rjsanyal/Photography/Chemistry&Process_of_Color_Photography.pdf

 

Rishi

[rishij]

Silver metal is invisible?? So then why on earth do I see my film darken when I take out a new roll and pull some film out and expose it?

 

It's because SOME of the silver ions get reduced to silver metal (uncharged) for some of the grains, and this is BLACK, with or without developer, it's BLACK, not INVISIBLE.

 

Which is why I see it.

 

Are you still trying to argue that there such a thing as a 'latent Ag (0)' vs a 'black Ag (0)' atom? They're one and the same thing.

[photo_smith]

I think trying to equate grain to pixels is wrong they are different technologies. Pixels are fixed in a grid zoom in you can

see this.

Film grains are stacked in 3 dimensions many layers deep and are random in size and dispersion, I don't think there are

any sensors out there that fit that description

 

In the end only those who wish to 'prove' how many pixels it take to out resolve 35mm will worry I'd guess we are close

but the two techs take a different approach to the same end, film will be percieved to have more grain and some will

object.

I like it! graininess is a product of the eye, my eyes like it.

going to bed....

[photo_smith]

It's because SOME of the silver ions get reduced to silver metal (uncharged) for some of the grains, and this is BLACK,

with or without developer, it's BLACK, not INVISIBLE.

You misunderstand silver halide is not black.

 

Here again is some info from Mees.

With the help of the developer, a single crystal of silver halide is CONVERTED to black metallic silver.

 

All the texts I have agree why not do some research?

try this because I have to go to bed, and I've got to drive a long way tomorrow.

http://aic.stanford.edu/sg/emg/library/pdf/vitale/2007-04-vitale-filmgrain_resolution.pdf

[vijay_nebhrajani]

<i>Please explain to me why a 35mm frame of film doesn't give me a 10 gigapixel image, if each silver grain is capable of displaying the entire dynamic range of film.</i>

<p>

Why do you keep confusing tonal range with resolution?<p>

In the digital world, I could have a phototransistor with area 1 inch by 1 inch that produces a current proportional to the light impinging upon it; I could use a 256 bit analog to digital converter to get a 256 bit representation of this current - with that I could represent 2^256 tones (or values of current, or values of light impinging on the phototransistor), yet I can't resolve any detail finer than an <b>inch</b>.

<p>

If I made an 8"x10" digital sensor with 80 of these phototransistors, I could at best get an 80 pixel image, but the range of tones would be nearly continuous (2^256 = 1.1579 x 10^77).

<p>

Please, please try to make this distinction clearly.

[rishij]

"You misunderstand silver halide is not black."

 

Mark, tell me you don't purposefully misinterpret what I write... I never said silver halide is black. I said the silver metal atom, which became charged 0 AFTER accepting an electron from a halide (or from the gold sulfide which was holding the electron that was donated by a halide), becomes black.

 

So I ask you again: are you saying that a 'latent silver atom charged zero after accepting an electron from a halide and/or gold sulfide' is any different than a 'black metallic silver atom'? Because they are one and the same thing.

 

And FYI your quote from Mees: "With the help of the developer, a single crystal of silver halide is CONVERTED to black metallic silver." argues against you. Read it again... it says 'a single crystal... is converted to black metallic silver'. It doesn't say 'a single crystal... has a proportion of its silver ions converted to silver metal, proportional to the amount of metallic silver atoms that were there to begin with at the sensitivity sites'.

 

OK reading your linked article. Agree you should probably stay away from this forum for now if you have a long drive tomorrow :)

 

Rishi

[vijay_nebhrajani]

Please consider this scenario:

<p>

Lets say that I take exactly four grains of silver halide - and these are R-grains (for Reichmann grains - that

are binary; i.e., they can be either completely opaque or completely transparent after processing). That is,

either they will convert to silver, or remain halide which will be cleared away.

<p>

Lets say I need one unit of light energy to "tickle" one grain such that it will eventually turn black. Let us

assume I expose these four grains with three units of light energy.

<p>

This must imply that three grains will eventually turn black, and one of them will not.

<p>

<b>Remember, the four grains are isolated in space by the gelatin emulsion, and luminance is continuous, meaning

that 3/4 of the light energy falls on each grain.</b> Each grain is identical to each other, meaning that its

"propensity" to turn black or remain clear is the same as all the other three grains (inviolate symmetry laws).

<p>

What mechanism would apply that would make one of these R-grains remain clear and three turn black? Did the grain

that remained clear realize that the three others have "decided" to turn black? Could the grain "measure" the

total light energy impinging on all four grains and figure out that this is only 3/4th the energy required for

all four

grains to turn black? How would it know what to do?

<p>

If it knew what to do, <i>film would be sentient</i>. If it didn't know what to do, what could be the possible

explanation for the four grains creating the five possible tones - or for film creating greyscale images?

<p>

Rishi, Daniel, please try to answer these questions - before quoting the rather arcane literature.

[bernardwest]

<i>Why do you keep confusing tonal range with resolution?</i><p>

 

I may be out of my league here, but I will give it a shot anyway. If the situation is a Michael Reichmann says it is, then the two are linked vis-a-vis: It takes a clump of film grains to allow the production of enough tones to match a typical DSLR pixel, such that the size of that clump is far greater than the size of a dslr pixel. Hence the resolution of film isn't say 2 microns, but more like say 60 microns.

[rishij]

Wait, Vijay, you're kidding me right?

 

You do know about the wave vs. particle theory of light, correct? In this case, we evoke the particle theory of light, and call each discrete packet of light a 'photon'.

 

Let's say, for argument's sake, one photon is enough to render one grain 'develop-able' (i.e. 3-4 silver ions are reduced to metallic silver atoms charged 0). In your scenario, the aperture/exposure would have to be such that within the given exposure time, 3 photons hit this cluster of 4 grains, and each encounter was 'productive'. Three photon 'absorption' events occurred. On 3 of the 4 grains. Because 4 grains can't absorb 3 photons.

 

Need I argue any further?

 

And all this talk of 'film being sentient' is really getting on my nerves. When you first brought it up, it made no sense within the context you brought it up in, and it is just as irrelevant now. Grains don't have to be sentient to clump together because THEY DON'T MOVE to clump together; it's just that there are a lot of grain particles to begin with within a given area and an area that experiences a lot of exposure has a lot of its grains turn 'develop-able' and subsequently 'black'... the more the exposure in a given area, the greater number of such grains that actually productively absorbed photons... therefore the more such grains within such an area that turn black upon development. I.E. a 'clump' forms. Not because grains moved to form said clump! But even within these 'clumps' there are grains that DON'T get developed because they didn't experience enough productive collisions with photons so they didn't have enough silver ions reduced to silver metal so these grains don't turn black and are washed away, leaving clear film base. The ratio of black metallic grains to clear film base within these 'clumps' then determines how black said clump is.

 

That is how clumps achieve tonality.

 

Clear?

[rishij]

Bernie - yes! Thank you!

<p>

Vijay: "Why do you keep confusing tonal range with resolution?"

<p>

I don't confuse them at all. In our scenario, they are intimately related. Because if Reichmann is right, then

theoretically many silver grains need to be used to represent a reasonable tonal range, thereby limiting your

ultimate resolution FOR A FIXED FRAME SIZE (e.g. 35mm). Why? Because you can only have X number of silver halide

crystals per 35mm frame. If 1 grain itself can represent 256 tones, and if X = 10 billion, then, theoretically,

if you had a lens capable of resolving that much detail onto a 35mm frame (probably impossible), you'd have a 10

gigapixel image. If, on the other hand, you needed 500 grains to represent 256 tones, then that region of 500

grains needs to be used to resolve any meaningful details for whatever given image element is falling on that

region. Thereby limiting the resolving power of the film to something more like 10 billion/500 = 20 megapixels.

<p>

<b>Hmmm</b>... which is near the calculated resolution of film (well, ok greater, but at least on the same order

of magnitude).

<p>

Coincidence?? <i>I think not!</i>

<p>

Rishi

[rishij]

I need to correct myself.

 

Earlier I wrote: "Let's say that a 35mm frame of 10 billion grains gives you a 10 million pixel image. So, 10 billion/10 million = 100 grains that collectively make up an 'imaging element', or analog equivalent of a 'pixel', in film."

 

I was off by a zero, obviously.

 

In other words, 10 billion grains/10 million pixels = 1000 grains that collectively make up an 'imaging element', or analog equivalent of a 'pixel', in film.

 

With three layers in color film, if we can generate a tonal range of 1000 per layer, that's 1000^3 colors that can be generated (in an additive model, yes, I realize... I don't know if this number changes for a subtractive color model), or, 1 trillion colors.

 

It has been argued that when scanning film, one should scan at a bit depth of 12-bits per color channel to get all the color information off the film. 2^12 is 4096. 4096^3 is 68 trillion.

 

So, we are off only a little over 1 order of magnitude here. Besides, in A/D conversion you need to sample at a higher 'resolution' (in this case, bit depth) in order to accurately represent all information because doing this avoids interpolation problems (when elements, or in this case colors, fall in between two bits).

 

I seriously doubt more than a 1 trillion colors are represented by slide film.

 

So, my point is: I think 1000 grains working together to form 'one resolving unit' of film (by resulting in clumps of varying densities) is reasonable, as it gives rise to a boatload of colors or tonal range.

 

I think that each grain being capable of displaying the entire tonal range is ridiculous, because then, theoretically, you could have a 10 gigapixel image on a 35mm frame (if you had a lens capable of resolving that sort of detail, which is impossible).

 

Please point out any flaws in my argument.

 

I'm still not entirely convinced by my argument, and I do still wonder if it could be a combination... i.e. silver grains are capable of displaying *some* tonal variety (like in the image Mark Smith posted), but ultimately it's the combination of the tonal variety of each grain AND the density of such developed/exposed grains vs. the density of clear film base within a given 'clump' (smallest 'resolving element' of film, equivalent to a 'digital pixel' in that it, this clump, can represent the entire tonal range exhibited by the film)... that gives rise to the final product.

 

Rishi

[rowland_mowrey]

Gentlemen;

 

There is such a thing as a continuous density wedge without steps! Yes, it is evaporated nickel onto glass. As

such, I have used it many times to evaluate images. With silver, when you trace a film curve, it has a smooth

continuous gradient from 0 - 6.0 (well 3.0 in silver and 6.0 in nickel)......

 

With a digital product, the steps are jagged. They look like a staircase. This is incontrovertable fact due to the

nature of analog vs digital. However, OTOH, at the atomic level, everything is done at the particle level, silver halide

involving 3 atoms of silver as a minimum for normal ET (electron transport). Here, with digital, you still see the stair

step effect, but with silver you see a "random walk" of particles.

 

Now, it is clear to me that these are gut arguments you all are presenting, not based on anything anyone has done

in a lab. I have spent most of my life measuring films and working with digatl people in R&D. Among other things,

all you digital guys ignore aliasing which exists in digital but not in analog. This interests me as it shows either a

lack of understanding or a wish to avoid a major problem in digital.

 

It is plain to me that everyone in the digital arena here seems to have a closed mind to the possibility that digital is

not yet perfect. Analog has been maturing over 100 years, but digital is the new kid on the block. It has lots of

potential, but isn't quite up to the task yet IMHO and based on measurements that I have made in the lab and

personally.

 

Best of luck to you all, but I can make 20x24 enlargements from 35mm and have proofs to show it. I cannot do that

with digital and I have proofs to show it. The data was obtained using a Nikon D70 vs a Nikon 2020 with Portra

160VC. The photos were side by side comparisons. Too bad. Digital lost! It has improved a great deal since 10

years ago, but you are using gut arguments to justify a move you really have no reason to have made. Many pros

are moving back to film. The data is shown in current Kodak and Ilford data that film sales of most analog products

is leveling off or increasing in the pro area.

 

Eventually, you will need stacked sensors with about 5 micron sides to produce what film can produce, or you need

MF or LF sensors. It can be done. I do not disagree but where we are now is not where film is.

 

Lets not forget the selenium, lead, arsenic and other pollutants in digital imaging products. (no mention of that here

so far either :D ) that amuses me a bit. Current B&W and color processes can be quite environmentally benign and

the film and paper manufacturing is quite benign as well.

 

Ron Mowrey

[vijay_nebhrajani]

<i>Wait, Vijay, you're kidding me right?

<p>

You do know about the wave vs. particle theory of light, correct? In this case, we evoke the particle theory of

light, and call each discrete packet of light a 'photon'.

<p>

Let's say, for argument's sake, one photon is enough to render one grain 'develop-able' (i.e. 3-4 silver ions are

reduced to metallic silver atoms charged 0). In your scenario, the aperture/exposure would have to be such that

within the given exposure time, 3 photons hit this cluster of 4 grains, and each encounter was 'productive'.

Three photon 'absorption' events occurred. On 3 of the 4 grains. Because 4 grains can't absorb 3 photons.

<p>

Need I argue any further?

</i>

<p>

Rishi, don't go off on a tangent. We are talking huge grains, around 10x10 microns in area. A single photon can't

do a thing. We are talking about a macro phenomenon, adequately addressed by luminance, no need for wave particle

duality. Gazillions of photons are hitting each grain simultaneously in my example. Yet one R-grain magically

decides to be unaffected by these photons, because after all it has to be binary, i.e., perfectly clear, since

the other three are going to be perfectly black - after all this must occur to get to 75% density, right?

<p>

If this were the case, by logical extension, this grain "knew" what to do and also knows what the other grains

will do in the future, with no physical connection to them. Sentience is the wrong term - fantasy is the right one.

<p>

Understand what I am saying before presenting the counterargument, please.

[hugh_templin]

I have been reading this thread for a few days and it has turned into an interesting theoretical discussion about the

resolution of 35 mm film. I have produced the best demonstration I have seen of how good a particular 35 mm picture

actually is and is in my gallery at http://www.photo.net/photodb/member-photos?user_id=698549 .

Starting at the right hand picture is the full frame scan of the Kodachrome slide, then a full width crop, then a crop

at the end of the path, then getting into the pixels, and the last is an enlargement of the actual pixels of the scan.

The slide is of the Public Gardens in Halifax, Nova Scotia which I took in the 1980's with my Pentax Spotmatic F

with 55 mm SMC Takumar lens on Kodachrome 64. I had it scanned for $25 with a CREO scanner at 4800 BPI, 16

bit TIFF, which produced 3957 x 5881 pixels (23.3 megapixels) and the file size is 136 megabites.

The enlarged pixels show that the heels of the man and woman are one pixel wide which means that the 35 mm

slide resolved at least the equivalent of a 23 megapixel digital camera. The grain is not even that obvious.

I hope the new Ektar 100 is this good.

 

Hugh