Wow - read this re: Film versus Digital debate!

<i>Because if a grain is not entirely clear and not entirely opaque, then it is not binary. Then Reichmann is wrong,

and his resolution estimate is wrong. Don't lose focus, Bernie.</i><p>

 

Without speaking for the others, I've never really been arguing the whole binary thing at the "grain" level. It's true I

have been attracted to Daniel and Rishi's reasoning and the literature Rishi has cited. But the main point I have been

exploring is the evidence that at 400x magnification (or roundabout) that negatives are clumps of black and clear. If

this is the case, then the reproduction of tones (and therefore the interpretation of tonal resolution) is clearly a binary

process. But as Rich has brought up a query regards to this interpretation, I am really going to have to wait to see

what comes of this. I might look for holes in your arguments, but I can't really argue the minutiae. But I would like to

get those definitions I was seeking though - it would help with my understanding.

Once again I find Daniel's reasoning hard to go past. I think that is a good point you made about reaction times (and a point I think(?) Rishi may have made earlier as well). Vijay seems to be thinking that the reaction must be instantaneous. Reactions, like the quantum shot noise I mentioned 4000 posts ago, follows some sort of distribution if I recall rightly. To think that the reaction should occur the instant developer contacts a sensitivity site is ridiculous.

Now the binary camp seems completely irrational:

 

Rishi says: "Right, but you also can't prove that grain is NOT binary by proving that light *can* pass thru it."

 

And here we were talking about "completely clear" and "completely opaque" - everyone has shown so many pictures

of "completely opaque" grain. If light can pass through it, you got three states - clear, midtone and opaque.

That is not binary. Ternary is not binary. What you are saying amounts to "binary = not binary".

 

Daniel says: "Nobody ever said that film was an example of a complete binary system." and "Neither a silver

halide crystal nor the overall development process is a binary switching system."

 

There are binary systems, ternary systems, n-ary systems (with n states) or there are continuous analog systems.

There is no such thing as an incomplete binary system. If you assert that the final states of a grain are either

clear or opaque, and you assert that the process to get from one to the other is not instantaneous, then you

assert that you can stop that process midway and get a value other than the two states (as the change from one

state to the other is happening), which means intermediate values are possible which negates the notion that it

is a binary system.

 

You don't seem to understand that the mere notion of having only two states in a physical system MUST imply

instantaneous (or happening in a vanishingly small time) switching. Stated differently, you CANNOT have exactly

two states for a system and at the same time have the system transition from one state to another in anything but

zero (or at least vanishingly small) time.

 

Again: binary (two values) implies switching. Not switching implies middle values are possible. If you think of

this in terms of 1s and 0s - if you can go from 0 to 1 in say 1 second, then I can stop the process of going from

0 to 1 at the 0.5 second mark and get a value between 0 and 1, which means the entity is not binary (as it can

have a value other than 0 and 1). I can also stop the process at the 0.25 second mark and get a value between the

0 value and the 0.5 value - ad infinitum - making all intermediate values possible. Meaning an analog system.

 

This is neither a strawman nor is it some kind of hypothetical logical argument. It is the nature of reality and

the universe around us. If a grain has to be binary (i.e., have only two values), it must switch from clear to

opaque in zero time (or vanishingly small time). If it can't do that, then it is not binary, and must have values

between clear and opaque.

 

This is exactly the same as water changing state to ice - a sudden process, and there is no intermediate state

between water and

ice. If you draw a graph of state vs temperature, as you linearly vary the temperature (decrease it slowly, and

no matter how slowly you decrease it) there is still a sudden transition point at 0 degrees C, when the water

suddenly becomes ice. Understand that "binary" (in terms of final states) and "switching" (as in state change in

infinitesimal time) are inseparable.

 

Now please explain to me, in the context of grains as a switching system, how images get formed on photographic

film and how developers work. Remember, once again, that if your explanation requires grain to not be a switching

system, it can't be binary (in terms of its final state - all opaque or all clear) either.

 

Clear? Or still opaque? (I think I'm rather pleased with that pun. Been meaning to do it for some time.)

<i>Now please explain to me, in the context of grains as a switching system, how images get formed on photographic film and how developers work. Remember, once again, that if your explanation requires grain to not be a switching system, it can't be binary (in terms of its final state - all opaque or all clear) either. </i><p>

 

I am not sure of your argument. You are saying that the conversion from clear to opaque must happen effectively instantaneously. I can't remember exactly, but has anyone said this can't happen? Do you think it can't happen? Like I said, I am not that familiar with the process, but I imagine it goes something like this: developer contacts latent image site; reaction follows the standard physical laws and possibly occurs at some point in the future; if reaction occurs, electrons are transferred (<b>effectively instantaneously</b>) to the grain where silver starts precipitating; if according to the laws of physics the reaction doesn't occur, the grain stays clear.<p>

 

What's so strange about this process?

Bernie: "What's so strange about this process?"

 

Nothing per se. So if it is true, then

 

A) There must exist a threshold for the state change in terms of exposure to light. (Like zero degrees to water, like the weight of a mouse to a mousetrap, etc.). It has been said that this is four silver atoms on a sensitivity speck.

 

(I forgot to mention this in my previous post about "binary" and "switching" being inseparable, but "binary", "switching" and "threshold" are all inseparable.)

 

B) If you put film in bright light, such that the threshold for ALL grains is met and they trip:

 

then

 

C) The final density of the film after development is no longer controllable by development time, because all grains have tripped, and the process to "develop" the film is instantaneous.

 

We know that statement C is untrue, so something is wrong: we made only one assumption - that the development time is instantaneous - so only that assumption must be wrong. Therefore, the development process must be continuous (analog). Meaning that the grain must go from clear to opaque non-instantaneously, meaning the process is "stoppable" (stop bath anyone?). Thus, a grain must be in some intermediate state between clear and opaque, ergo it is not binary.

<P>Another comment caught my eye...</P>

<P></P>

<P>Vijay, Re: carbon bonds in diamond</P>

<P></P>

<P><i>The point is that the distance between two atoms is 0.000154 microns. Even if the atoms had zero size,

0.000154 microns (the "gaps" between the atoms) is smaller than the wavelength of visible light - 0.4 microns by

a factor of over two thousand, five hundred (2597.4). But visible light passes through these gaps just fine.</P>

<P></P>

<P>Once again, the thrust of my argument is this: You can't prove that a grain is opaque (to visible light) based

on the statement "gaps between silver filaments in grain are smaller than the wavelength of visible light."</i></P>

<P></P>

<P>The analogy to a diamond is a false one. In a diamond the organization of atoms allows photons to pass with

little interference. The substance is said to be transparent. But silver atoms in a solid state interfere with

passing photons, hence silver is considered opaque.</P>

<P></P>

<P>If you have a material which is opaque to a given wavelength of radiation, and that material has a hole that

is smaller than the wavelength of said radiation, it will effectively block the radiation. You can experimentally

prove this by standing in front of your closed microwave while it's heating coffee. The metal in the window is

opaque to both microwave radiation and visible light. The holes are much smaller than the wavelength of the

microwave radiation generated inside, but much larger than the wavelengths of visible light. This means visible

light can get through the holes to your eyes and you can observe your coffee warming up without being fried by

the microwave radiation warming it, which cannot pass through the holes.</P>

<P></P>

<P>This is admittedly a simplified view that doesn't account for evanescent waves or the new experiments showing

that for some materials under certain conditions it is possible to pass specific wavelengths of electromagentic

radiation through holes smaller than the wavelengths. But it's a simplified view that works for what we're

discussing. For all intents and purposes, gaps between filaments of silver in a single grain will not pass

visible light if they are smaller than the wavelength of said light.</P>

<P></P>

<P>So do gaps larger than the wavelengths of visible light occur? Let's say, for the sake of argument, that some

do. They still would not pass enough light to affect viewer perception, and that's key in this discussion of the

scale at which tonal dithering occurs. Let's say one filament gap forms in one grain of silver which is large

enough to pass visible light. Does that mean the speck of silver will appear as less than fully black? Not to a

human observer, not even at 400x magnification. It's like taking one dye molecule away from a dye cloud and

claiming a distinct tone. No observer would actually be able to tell the difference.</P>

<P></P>

<P>Let's say, for the sake of argument, that the growth of silver filaments could be precisely controlled in an

experiment such that half the area of the silver speck were composed of gaps large enough to pass light. Would

you see a 50% gray grain? Maybe at high enough optical magnification. Would you see a 50% gray spot in a 10x

print? Nope.</P>

<P></P>

<P>Tonal rendition just does not occur at the scale of a single grain of silver deposited from a single silver

halide crystal. The scale is too small to affect perception at normal print sizes. An entire single grain is too

small to affect perception at normal print sizes! That is to say if you had two prints and precisely removed just

one grain of silver from the negative before making the second print, no human could tell the difference, even if

you pointed them to the region where the grain had been removed. Details and tones are formed by clusters of

grains. The size of a single grain contributes, but the grain itself is not anything other than black. Most, if

not all, gaps between filaments within a single grain are too small to pass any light at all

which is why we image them with electron microscopes.</P>

<P></P>

<P>It's just pointless to keep arguing that in some way individual grains render tones. They don't. Tones are

rendered through clusters of silver deposits or grains.</P>

 

Daniel said: "Tonal rendition just does not occur at the scale of a single grain of silver deposited from a single silver halide crystal."

 

What if we make a single silver halide crystal 1mm x 1mm? What if we make it 10mm x 10mm? It is a crystal, we can grow it, can't we?

 

Then do you propose that the entire crystal will suddenly turn opaque on first contact with a developer? If not, then what is the threshold above which the crystal behaves linearly, and below which it behaves binary?

<P><i>There are binary systems, ternary systems, n-ary systems (with n states) or there are continuous analog

systems. There is no such thing as an incomplete binary system. If you assert that the final states of a grain

are either clear or opaque, and you assert that the process to get from one to the other is not instantaneous,

then you assert that you can stop that process midway and get a value other than the two states (as the change

from one state to the other is happening), which means intermediate values are possible which negates the notion

that it is a binary system.</i></P>

<P></P>

<P>Developer converts silver halide to silver. How much silver depends on the original exposure of the silver

halide crystal and the development parameters. The tone of silver is never in play during the reaction. Silver is

silver and appears black in this context. The amount of silver is what's in play.</P>

<P></P>

<P>Saying that silver grains always appear as black specks on photographic film does not in any way imply or

require a binary system. You're arguing a strawman.</P>

<P></P>

<P><i>You don't seem to understand that the mere notion of having only two states in a physical system MUST imply

instantaneous (or happening in a vanishingly small time) switching.</P></P>

</i></P>

<P>There aren't two tonal states for silver, there's one. If silver exists on film, it's black. Period. The only

way you don't get black is if there's no silver deposited on that particular spot. Development produces silver.

Conversion of the entire grain takes time, and can be stopped midway. But that only alters the amount of the

silver created. Any silver that is created is the tone of silver.</P>

<P></P>

<P>If you must have a binary flip, I would say that at the scale of a single atom, the conversion is for all

intents and purposes instant or unstoppable. You won't ever end up with "half" of a silver atom. Silver atoms are

there or not. If they're in a cluster large enough to observe, they're black. If they're not, then one perceives

the clear base the film rests on. But tone is never in play. There's no mid gray silver in photographic film.</P>

<P><i>The final density of the film after development is no longer controllable by development time, because all

grains have tripped, and the process to "develop" the film is instantaneous.</P>

<P></P>

<P>We know that statement C is untrue, so something is wrong:</i></P>

<P></P>

<P>What is wrong is your assumption that all silver halide crystals will react equally to the developer. Silver

halide crystals are not uniform on film. Some take longer to develop out than others. If you cut the time enough,

some crystals will not develop out or will partially develop out. This reduces the density of silver on the film,

producing less than solid black when viewed at low magnification. The production of a single atom of silver is

effectively instant, but developing out an entire crystal of billions of molecules to silver atoms takes time.</P>

<P></P>

<P>But the tone of the silver is never in play, only the amount. Silver is silver. It has the tone it has.</P>

<P></P>

<P><i>Thus, a grain must be in some intermediate state between clear and opaque, ergo it is not binary.</i></P>

<P></P>

<P>Silver atoms on film are never in an intermediate state between clear and opaque. They are always opaque. The

size of a silver deposit from a single silver halide crystal changes over time in developer. The intermediate

state would be a smaller grain speck than full development would produce. But silver is always opaque.</P>

<P></P>

<P><i>What if we make a single silver halide crystal 1mm x 1mm? What if we make it 10mm x 10mm? It is a crystal,

we can grow it, can't we?</P>

<P></P>

<P>Then do you propose that the entire crystal will suddenly turn opaque on first contact with a developer?</i></P>

<P></P>

<P>I propose that it will take some time for the developer to convert the billions upon billions of molecules

into silver atoms. The silver atoms that will be produced will be opaque because silver is opaque. The number of

atoms produced will depend on development time. In this example you will have gaps large enough to pass light and

potentially have something you can call a grain which appears "gray" at sufficient distance, but only because you

scaled the crystal from a micron scale to a mm scale. There aren't mm sized crystals in photographic film.</P>

OK, Daniel, now I seem to be making some headway.

<p>

<i>How much silver depends on the original exposure of the silver halide crystal and the development parameters.</i>

<p>

Question: So then a grain of size 10um x 10um that has 10% of its silver halide molecules converted to silver

will look exactly the same optically as a grain of size 10um x 10um that has 90% of its silver halide molecules

converted to silver?

<p>

<i>Saying that silver grains always appear as black specks on photographic film does not in any way imply or

require a binary system.</i>

<p>

Yes it does. Saying that an optically observable speck of silver is a grain (A) is not the same thing as saying

that a silver halide crystal, isolated from other silver halide crystals in an emulsion (B) is a grain.

<p>

B is the accepted definition of grain and that is what I have been talking about. B can't be binary.

<p>

If you want to stick to the definition of grain as A, then you have to admit that such a speck can be of any

size, must necessarily be smaller than a crystal B (because B is isolated in emulsion), and many of such specks

could reside in a single crystal B.

<p>

If many of these specs reside in a crystal, then see my question at the beginning of this post. Would a crystal

as defined by B of size 10um x 10um with 10% specks look like one of the same size with 90% specks?

<p>

<i>There aren't two tonal states for silver, there's one. If silver exists on film, it's black. Period.</i>

<p>

What if there's just one atom of silver there? What is its tonal state? What if there are 100 but they are 1 atom

width thick?

What if they are 10 atoms thick? Would they go linearly from transparent to opaque as the thickness of the silver

film increased? Or is that binary too - as soon as an atom is present, it is opaque? Is opacity a property of the

atom? Diamond vs graphite?

<p>

<i>If they're in a cluster large enough to observe, they're black.</i>

<p>

Observe by what mechanism? What is the threshold of "cluster large enough to observe"? So if I take a silver coin

and keep dividing it in half, at some point in time it will suddenly go transparent to the eye? At what size?

Daniel: "Silver atoms on film are never in an intermediate state between clear and opaque. They are always opaque."

 

Then that is the absurdity in the reductio ad absurdum proof. I rest my case. Opacity is not an atomic property.

Daniel: "What is wrong is your assumption that all silver halide crystals will react equally to the developer. Silver halide crystals are not uniform on film. Some take longer to develop out than others."

 

Two crystals, both made of the same matter, both with the same density of "sensitivity specks" etc., will react differently to the same developer? Unless you can point to something that is different about the crystals, you are breaking fundamental cause and effect laws (causality, or identical inputs to identical systems results in identical outputs). The crystals are on the macro scale no less, so you can't do the probability theory thing - that only applies at quantum scales.

 

I mean you can make finer crystals by the process of mechanical crushing - say from the same huge 10 kg crystal - and those finer crystals are not identical in terms of properties?

Or ask yourself: if I created a manufacturing process such that every silver halide crystal is exactly identical to every other, then the photographic film I produce with that silver halide will behave differently than a "regular" film?

This is farcical...<p>

 

<i>A) There must exist a threshold for the state change in terms of exposure to light. (Like zero degrees to water, like the weight of a mouse to a mousetrap, etc.). It has been said that this is four silver atoms on a sensitivity speck.</i><p>

 

Of course there is a threshold. We've been trying to explain that all along. The threshold is number of silver atoms at sensitivity site <b>AND</b> the developer. If both the conditions are met, then the threshold is met. ONce the threshold is met, the reaction at the atomic level proceeds <b>instantaneously</b>. It should be so simply clear that this is the case. I feel that you have bogged yourself down in inumerous thought experiments that simple thinking has become foreign. Please explain your reductio ad absurdum argument to me again (as I have lost where it originally started in the above theses), and I will finally put this to rest for you.

<i>Two crystals, both made of the same matter, both with the same density of "sensitivity specks" etc., will react differently to the same developer?</i><p>

 

Yes, if they are different shapes and sizes. 'Cause and effect' doesn't exist in a vacuum. It is dictated to by the same physical laws as the rest of us.

<P><i>Question: So then a grain of size 10um x 10um</P>

<P></i></P>

<P></P>

<P>Grains range from 0.2-2 microns. As I pointed out earlier most of the specks we might call a "grain", even at

400x, are actually clumps of grains. Many individual grains are not large enough to even be observable if they

were standing alone, much less convey a tone based on filament gaps (most of which can't even pass light). But

multiple crystals in a region develop out and you see the black clump. The largest crystals developed out would

be just observable at 400x.</P>

<P></P>

<P>Your hypothetical increases the grain size so that you can attempt to argue that it might develop out in a way

that leaves light-passing gaps so as to appear gray at some magnification. Maybe that would happen sometimes if

grains were 10 microns wide, though the possible tonal states would be quite limited as compared to a sensor. But

grains are not 10 microns wide. And they're just not observed as anything other than black.</P>

<P></P>

<P>You keep trying to argue from logic and theory. <i>Theory must bend to observation.</i> I don't see any gray

grains under a microscope. Do you? It's on you to explain why. And if you insist that tonality is rendered at the

level of the individual grain, then you must explain how that tonality impacts observation at 10x yet is

invisible at 400x, because everything I see (that's in focus) at 400x is either black or clear.</P>

<P></P>

<P><i>Saying that silver grains always appear as black specks on photographic film does not in any way imply or

require a binary system.</P>

<P></P>

<P>Yes it does. Saying that an optically observable speck of silver is a grain (A) is not the same thing as

saying that a silver halide crystal, isolated from other silver halide crystals in an emulsion (B) is a grain.</P>

<P></P>

<P>B is the accepted definition of grain and that is what I have been talking about. B can't be binary.</i></P>

<P></P>

<P>It is what I have been talking about as well. But A vs. B is not relevant. Silver is silver. It is opaque. On

film it appears black. One tone. <b>This does not imply a binary system.</b> If you have silver on film it's

opaque because that's the nature of the material.</P>

<P></P>

<P><i>What if there's just one atom of silver there? What is its tonal state?</i></P>

<P></P>

<P>It's not optically observable because it's not large enough to interfere with enough photons of visible light

to be observed, so there's no such thing as a "tonal state".</P>

<P></P>

<P><i>What if there are 100 but they are 1 atom width thick? What if they are 10 atoms thick?</i></P>

<P></P>

<P>You're playing games at this point. If a deposit of silver (from a single silver halide crystal) is optically

observable on photographic film, it appears black.</P>

<P></P>

<P><i>Or is that binary too - as soon as an atom is present, it is opaque?</i></P>

<P></P>

<P>Once a cluster of them becomes large enough in both length and width to be optically observed it will be

observed to be a single black particle even though electron microscopes reveal a more complicated structure. That

structure is at too small a scale to be optically observable. </P>

<P></P>

<P><i>Is opacity a property of the atom? Diamond vs graphite?</i></P>

<P></P>

<P>A property of the arrangement of atoms.</P>

<P></P>

<P><i>Observe by what mechanism?</i></P>

<P></P>

<P>Visible light through an optical microscope.</P>

<P></P>

<P><i>What is the threshold of "cluster large enough to observe"?</i></P>

<P></P>

<P>I don't know because I don't know off hand what the maximum possible magnification is with optical equipment

in the visible spectrum.</P>

<P></P>

<P><i>So if I take a silver coin and keep dividing it in half, at some point in time it will suddenly go

transparent to the eye? At what size?</i></P>

<P></P>

<P>At the size that is just below the human observer's ability to resolve detail for the given distance from

his/her eye to the theoretical silver coin, taking into account lighting conditions. This will vary from human

observer to human observer. The size will be much, much larger than what can be seen with the aid of an optical

microscope.</P>

<P></P>

<P><i>"Silver atoms on film are never in an intermediate state between clear and opaque. They are always opaque."

Then that is the absurdity in the reductio ad absurdum proof. I rest my case. Opacity is not an atomic

property.</i></P>

<P></P>

<P>Silver <b>atoms</b> (plural) on film are in a solid state, and solid silver is most definetly opaque.</P>

<P></P>

<P><i>"What is wrong is your assumption that all silver halide crystals will react equally to the developer.

Silver halide crystals are not uniform on film. Some take longer to develop out than others."</P>

<P></P>

<P>Two crystals, both made of the same matter, both with the same density of "sensitivity specks" etc., will

react differently to the same developer?</i></P>

<P></P>

<P><b>Silver halide crystals are not uniform on film.</b> They vary greatly in size, shape, available sensitivity

specks, etc. Neither is the time or nature of their exposure to developer uniform (why do you think you

agitate?).</P>

<P></P>

<P><i>Unless you can point to something that is different about the crystals,</i></P>

<P></P>

<P>They vary in size, shape, orientation, position in the gelatin, available sensitivity specks, exposure to

light, and exposure to developer.</P>

 

<h2><u>My Final Conclusion (for now...)</u></h2>

<p>

Vijay: <i>"You don't seem to understand that the mere notion of having only two states in a physical system MUST

imply instantaneous (or happening in a vanishingly small time) switching."</i>

<p>

Folks, I think we should allow Vijay to continue arguing with himself. I think I can safely say that neither Daniel nor I,

nor Reichmann nor Adams, are of the 'binary camp'. We're of the 'binary in tone' camp. Grain itself is not a binary

switching system... I think we're all starting to reach that conclusion and, Vijay if you actually paid more attention to

what we wrote, you woulda seen this by now and you woulda stopped jumping at the first opportunity to attack us

when we say anything that remotely resembles saying that anything in film is binary. I mean, did you just <b>gloss

over</b> what I said when I wrote:

<p>

<i>"At any rate, I don't think this is relevant because we should probably shift the discussion from talking about

whether a 'grain' itself is binary to whether or not the filamentous growths growing out from a sensitivity center is

binary (which I think it is in terms of opacity, but is analog in terms of size). The grain, then, just becomes an

element in the film that presents sensitivity centers for filamentous Ag outgrowth. which means now we're asking 'is

the sensitivity center' binary? To which I say, probably not, because the number of initial reduced silver atoms at a

sensitivity center, determined by photon exposure, determines the final size of the resulting filamentous

outgrowth."</i>

<p>

So, Vijay, quit explaining <i>ad nauseam</i> what binary is. It's condescending, and we're all well aware of what

binary is. Daniel has already admitted to filaments growing from reduced silver nuclei (at sensitivity sites) at some

rate. The initiation of this reaction is contingent upon at least 3 reduced silver atoms clustered at a sensitivity site,

more likely to initiate if there are more, but only up to a certain point (I remember reading somewhere '50' reduced

silver atoms)... probably because whether or not you have 20 or 40 reduced silver atoms at the sensitivity site, the

developer will easily pass electrons through these reduced silver atoms to nearby AgBr. This is why there's a cap on

how much you can increase the sensitivity of emulsions.. you can increase size, therefore sensitivity, up to a certain

point, beyond which you have diminishing returns because you've increased the number of 'ears' from which the

reduction reactions can proceed to a point where, for any reasonable development time, you'll reduce all the AgBr in

the grain. It's a surface area/volume ratio optimization... keeping volume down reduces apparent grain in the final

negative... but as you increase this ratio, you have more points, on the surface, from which the reduction reactions

can initiate and proceed toward the center of the grain (containing all the unreduced silver ions, as AgBr). Hence, the

overall grain is more sensitive to becoming exposed upon illumination, because with the increased number of

sensitivity sites, more encounters with photons are 'productive' (resulting in latent sensitivity centers), and so the

easier it is for more AgBr salts to be reduced within the crystal because there are more sites from which the

reduction reactions can initiate when soaked in developer. Now, this reduction of AgBr salts within the grain occurs

at some rate. Stop the development process earlier, not as many electrons make it from developer through the

cluster of reduced metal silver atoms, and less of the AgBr within the grain become reduced. Let it go longer,

electrons keep channeling through the metallic silver at all the sensitivity sites of a grain, and the whole grain goes to

black.

<p>

So does that mean that the grain can have more states than just opaque or undeveloped? Yes! Does that mean it is

not binary? Yes! Vijay, you should be rejoicing. Do a little dance.

<p>

Now, to rain on your parade, do I <i>care</i> if the grain is binary or not? Nope. Here's where I shift the discussion to

what I think is more relevant.

<p>

After the reduction reactions are allowed to proceed, eventually the remaining AgBr in the grains (not reduced) are

dissolved and washed away. So, effectively, I imagine the 'grains themselves' are now gone... i.e. they are no longer

autonomous structures of AgBr. They have now been reduced (pun intended) to a bunch of sensitivity ears and the

filamentous growths growing from these sensitivity ears. The more 'latent' (exposed to photons) sensitivity centers a

particular grain had, the more the number of filamentous growths resulting. The more the reduced silver atoms

each 'ear' had before development, the larger the resulting filamentous growth, because the higher the probability that

the reaction was initiated earlier on in the development process (& therefore the longer this filamentous growth had

to, er, grow).

<p>

Now, let's take a step back. Who cares what the overall tone of the initial 'grain' is now? What's important now is

these filamentous growths of reduced silver, nucleated with a sensitivity center. These growths are black, opaque.

They vary in <b>size</b>. When one filamentous growth from one end of the grain grows large enough to contact

another filamentous growth from a sensitivity center on the other end of the grain, they 'clump' together. The size &

number of these clumps, separated by portions of clear film base (or not, for a very exposed area... well except for

where there's gelatin of course), when viewed at a lower magnification level, then determine the tone of that spot.

<p>

How's that? It pretty much reconciles all camps. Everyone should be happy now :)

<p>

OK it's never that simple, so bring your criticisms & critiques!

<p>

Rishi

Bernie: "Yes, if they are different shapes and sizes. 'Cause and effect' doesn't exist in a vacuum. It is dictated to by the same physical laws as the rest of us."

 

See my post at Nov 14, 2008; 02:13 a.m.

I want to modify what I just said. I now notice that Vijay you are talking about same density (I assume you really mean number?) of sensitivity sites. Perhaps in this case the reaction will proceed the same in both (if they have the same number of silver atoms at each sensitivity site), or perhaps not (I can't be sure). But the point DAniel has been trying to make is that they DON"T all share the same properties. HEnce the variance in development.

Bernie - I can't believe I'm defending my theory (er...Adams and Reichmann's) when observation supports the theory, and Vijay is not defending his when observation contradicts his!

 

If individual silver grain particles on film can appear gray, why have I never seen one? Neither did Adams who spent more time with B&W film than I will in my life. Neither has Reichmann. Is there any evidence of these gray grains? Any evidence of tone being rendered at the level of the individual grain? If not why can't we observe them? And if we can't observe them at 400x or even 60x, why would they impact viewer perception of tone in a region on a print, say 10x?

 

I want Vijay to play defense for a while since observation matches Reichmann's theory ;-)

Bernie: "I now notice that Vijay you are talking about same density (I assume you really mean number?) of sensitivity sites."

 

Yeah, same number per unit volume of the crystal. Double the crystal, double the sensitivity sites etc. Hence, density of sensitivity sites. Easy to achieve by crushing a large crystal to get smaller sizes.

 

Bernie: "But the point DAniel has been trying to make is that they DON"T all share the same properties. HEnce the variance in development."

 

OK, so if I somehow take identical crystals and make film out of it, it will behave differently than regular film then? We must have crystal variance to make photographic film?

Rishi - I couldn't have typed it better myself :-)

 

Nice summary conclusion. Can we argue Canon vs. Nikon now? ;-)

<P><i>OK, so if I somehow take identical crystals and make film out of it, it will behave differently than

regular film then? We must have crystal variance to make photographic film?</i></P>

<P></P>

<P>I would argue that you need it to make good photographic film. If by some miracle of modern nanotechnology you

could coat a film base with truly identical crystals, all orientated the same exact way towards the light, I

would think that you would end up with a film with much more contrast, closer to monochromatic than we would want

film to be. It might not be perfectly monochromatic...exposure will determine the degree to which crystals

develop out into silver, hence yielding different densities...but it wouldn't have the nuance of a film with

variable crystals.</P>

<P></P>

<P>At least that would be my guess. Not having the chance to actually work with such a material I couldn't say

for sure. Perhaps if you had such nanotechnology you could perfect each crystal so that all the density range and

nuance you need can be achieved with one crystal size.</P>

<P></P>

<P>Keep in mind that, at least with today's technology, B&W films often incorporate multiple layers, each layer

having a different average crystal size, to increase dynamic range. (Or so I've read.)</P>

Rishi - I'm sorry - I didn't intend to gloss over what you said - I missed it altogether in the heat of things.

 

Whatever you have been saying in your last post (Rishi Sanyal , Nov 14, 2008; 02:31 a.m.) has been exactly what I have been saying all along. That those silver specks you see under a microscope must be subgranular structures - that a single crystal site isolated by gelatin could have several of these - thereby creating a "halftone grain as in halftone in the same AgBr crystal site" - therefore resolution can't be determined by 40-60 grains (as in original AgBr crystals) together, but by 40-60 of your subgranular, nucleated filamentary structures.

 

Thereby making Reichmann's estimate of film resolution incorrect - because he talks of 5 micron grains for determination of size (this size estimate comes from AgBr crystals) and then jumps to tone being generated by 40-60 microscopically observable grains (grain definition at this time has changed to your subgranular, nucleated filamentary structures) but without revising the size estimate for these grains.

 

At this point, Rishi, you and I are in agreement about everything except that you haven't said that Reichmann is wrong. So do you agree then that Reichmann's film resolution estimate results in too low a number?

Daniel: "It might not be perfectly monochromatic...exposure will determine the degree to which crystals develop

out into silver, hence yielding different densities..."

 

I know that the argument is probably over, but that is exactly the point I've been trying to make - you could get

different densities, and that would make grain (as in the B definition) not binary. Tada!

 

See I've been trying to disprove Reichmann's estimate of film resolution all along (I can now gloat that I never

lost focus) - and hopefully you all see Reichmann's error too.

 

That may make Ken Rockwell right (much to the horror of some, I know).