Wow - read this re: Film versus Digital debate!

Bernie: <i>"Surely if you had of scanned your film in at 78MP, you would see the same thing but with multiple pixels representing the heels"</i>

<p>

Yes but if it had multiple pixels representing the heels, then we'd not call it 78MP of resolution. We'd look elsewhere in the image to see if we could find a detail represented by one pixel. If we could find one, then we could say that film resolved on par with a 78MP sensor. For a 35mm frame of film, I doubt you'd ever find any feature represented by 1 pixel (assuming you could get a 78MP scan!). I actually believe that Hugh is spot on with his analysis, though I think he's giving the film too much credit by saying the heel is resolved by 1 pixel... more like 2 :) Making it more of a 11.5MP resolution frame.

<p>

But in essence his analysis is right.

<p>

Rishi

Rishi: What I meant to say is that you'll start to have diffraction effects when you have gaps, amongst opaque material, whose size are on the order of the wavelength of light. So light won't just happily transmit thru as if the gap were much wider.

 

So as light passes through these "gaps", you'd expect to see interference patterns, then? Or polarization perhaps? What would make that light "unhappy" as it passes through that gap?

Vijay, remind me why this is relevant. Because I think we have much more to argue over. I'm trying to draw an image that is going to reconcile both what you and Daniel are arguing... wouldn't that be amazing :)

 

Rishi

Rishi: I actually believe that Hugh is spot on with his analysis, though I think he's giving the film too much credit by saying the heel is resolved by 1 pixel... more like 2 :) Making it more of a 11.5MP resolution frame.

 

The limiting factor you see here is the scanner, not the film. Ask yourself this: If the scanner could resolve four times as much linear detail, would the heel - as represented by sixteen pixels - show more information? Since you (or I) don't know, we can't draw any conclusions. Sorry.

Vijay, you're right. The limiting factor is the scanner here. I agree. But, an Imacon is capable of 80MP scans of 35mm film. And I've yet to see a detail resolved by 1 pixel in such a scan. I'll keep looking though :)

 

Even when I make an 80MP scan and resize to 20MP, the smallest detail I see takes up ~2 pixels... I should probably try and scan a frame, though, that has like the smallest detail in the frame that I have on any of my slides... that'd give me a better idea.

Rishi: Vijay, remind me why this is relevant.

 

I dunno man, you brought it up. The rest of us were trying to point out that opacity is not an atomic property. A 20 micron thick film of gold is transparent, for instance, as Rich pointed out (grains aren't even that thick, I assume) and I pointed out that any thickness of diamond is transparent and graphite is opaque; both being pure carbon.

 

So the argument that because grain filaments cannot be seen with wavelengths in the visible region, grain must be solid and perfectly opaque holds no water. Carbon atoms can't be seen with wavelengths in the visible region either, but they can form perfectly transparent, or perfectly opaque substances (diamonds, graphite).

Rishi: Vijay, you're right. The limiting factor is the scanner here. I agree. But, an Imacon is capable of 80MP scans of 35mm film. And I've yet to see a detail resolved by 1 pixel in such a scan. I'll keep looking though :)

 

Yeah, but there are two different things here: one is practical - the actual resolution you see with some lens, some film and some camera (think shutter etc vibrations) - and the other is the limit of resolution of film. We are talking about the latter, and trying to derive some theoretical upper bound. That you haven't hit this resolution (because several factors could have derailed you - like poor lens resolution, vibration, etc) doesn't lower the upper bound, see?

Sorry Jorge, I didn't mean to come across as arrogant. Apologies again - as far as this concerns me, I

pre-apologized for myself (and others) that this thread was becoming arcane and that I was contributing to the

arcane-ness. I also requested that we be "please please" allowed to continue, in all humility.

 

I don't claim to be too smart to answer a simple question - I have been, on pain of being intolerably repetitive,

trying to explain the binary thing, without losing patience, without name calling, and without any ad hominem

attacks. I have agreed that this has nothing to do with the art of photography, but photography is both an art

and a science. I have also pointed out that this discussion has some relevance to the original question.

 

I shouldn't have said I find Philip's attitude "somewhat arrogant" - I think I find it "somewhat ungracious" -

poor initial choice of words on my behalf, and for that I apologize again. I was a little frustrated that after

such such an excellent discussion, the original poster didn't even see value in it, or be happy that he had

started such a good thing.

<i>So the argument that because grain filaments cannot be seen with wavelengths in the visible region, grain must be solid and perfectly opaque holds no water. Carbon atoms can't be seen with wavelengths in the visible region either, but they can form perfectly transparent, or perfectly opaque substances (diamonds, graphite).</i><p>

 

Why are we arguing about this?!? I've already stated that it's not the atom that matters, it is the distances between atoms that allow light through. And besides, as Vishi agrees, we have our heads in the wrong frame of reference. We should be getting to the bottom of whether Adams, Daniel, and Kodak used brightfield microscopy to see black clumps on the negative. If they did, this argument is over. If they didn't, well we need to see some new examples.

re. the heel thing. I see what you are saying Rishi about the 1 pixel detail needed. But like I said earlier, it is clearly more than 1 pixel wide. And besides, anti-aliasing, sharpening and noise reduction will fudge this result so much it can't be considered relevant evidence.

@ Bernie West, Nov 13, 2008; 06:04 p.m.

 

Re: Your hummingbird analogy.

 

Sure, the threshold will be "tripped" by the falling hummingbird, but only if the trap is set. If the trap is already sprung, the hummingbird's fall produces no output.

 

This means that on real film, exposed silver grains will immediately turn black (on first contact with developer), and increasing development time would have no effect. Try this: take a roll of film and pull it out of the cannister and expose it to direct sunlight for 10 minutes. At this point you should be fairly sure that all mousetraps have sprung with the mice, right?

That means the hummingbirds can't do anything further to spring the traps.

 

Now keep the film in the developer for its full development time, you should see all black, right? Now go half development time, you should still see black, correct? I mean, all mousetraps have already sprung. Go for quarter development time; once again, same result, black. All sprung traps. Same for an eight development time, etc... which means that at first contact, the film will be developed. Meaning no push or pull can be possible.

 

Does this really happen? Maybe grain isn't like mousetraps at all. But that is like saying (gasp) grain is not binary.

Bernie: I've already stated that it's not the atom that matters, it is the distances between atoms that allow light through.

 

This means that:

 

1. Atoms are solid - light can't pass between the nucleus and the electron orbitals.

 

2. Diamond should be completely opaque, since there is actually no space between the atoms - after all a C-C bond implies that electron orbitals overlap, or at least touch.

 

Man Bernie, don't go turning physics on its head.

<I>Now keep the film in the developer for its full development time, you should see all black, right? Now go half development time, you should still see black, correct? I mean, all mousetraps have already sprung. Go for quarter development time; once again, same result, black. All sprung traps. Same for an eight development time, etc... which means that at first contact, the film will be developed. Meaning no push or pull can be possible.

 

</i><p>

 

I haven't developed my own film since high school, so once again, I can't comment too deeply on what you are saying. But I would like some terms clarified so that I might. Is the filamentous structure we see in Daniel's Kodak pdf - figure (e) - one or many 'grains'? Or from another angle, can one single grain look filamentous, or is a single 'grain' that triangular shaped thing that you highlighted yellow in the electron micrograph above? If a single developed 'grain' is filamentous, what is the filament (chemically/physically speaking) comprised of? Is it a string of bonded silver atoms that started at the 'ear' of the grain, or is it actually a string of many grains? If I can get my head properly around these things I hope then I might be able to answer your questions a bit better.

<i>This means that:

 

1. Atoms are solid - light can't pass between the nucleus and the electron orbitals.

 

2. Diamond should be completely opaque, since there is actually no space between the atoms - after all a C-C bond implies that electron orbitals overlap, or at least touch. </i><p>

 

I'm not familiar with how the carbon bonds in a diamond. But in other materials, the molecules form crystal structures which presumably have a large amount of 'nothing' in between, and which the light is able to pass through.

And I should have added to the list of explainations to give me: What does happen when you only partially develop a fully exposed roll of film?

Found this in Wikipedia:<p>

 

<i>Reduction potential of the developer<p>

A developer solution must have a reduction potential that is strong enough to develop sufficiently exposed silver

halide crystals having a latent image center. At the same time, developer must have reduction potential that is weak

enough not to reduce unexposed silver halide crystals.<p>

 

In a suitably formulated developer, electrons are injected to the silver halide crystals only through silver speck (latent

image). Therefore it is very important for the chemical reduction potential of the developer solution (not the standard

reduction potential of the developing agent) to be somewhere higher than the Fermi energy level of small metallic

silver clusters (that is, latent image) but well below the conduction band of unexposed silver halide crystals.<p>

 

Generally, weakly exposed crystals have smaller silver clusters. Silver clusters of smaller sizes have higher Fermi

level, and therefore more crystals are developed as the developer's reduction potential is increased. However, again,

the developer potential must be well below the conduction band of silver halide crystal. Thus there is a limit in

increasing the photographic speed of the system by boosting the developer potential; if the solution's reduction

potential is set high enough to exploit smaller silver cluster, at some point the solution begins to reduce silver halide

crystals regardless of exposure. This is called fog, which is metallic silver made from non-imagewise (exposure-

nonspecific) reduction of silver halide crystals. It was also found that, when developer solution is optimally

formulated, the maximum photographic speed is rather insensitive to the choice of developing agent (James 1945),

and there exists a limit for the size of silver cluster determining the developability of the crystal.</i>

In the late 1970's Kodak got alot of data packed into a 35mm piece of film too at their San Diego skunk works. Now if only if we could get Joe Six pack and Joe the plumber to realize that their pictorial images are not good and they must except pure Backs and whites to get these fantastic high megapixel equalavelent numbers for a piece of film.<BR><BR> This debate is now 3 decades old. <BR><BR>Folks till prefer pictoral images. Few folks really get even 50 line pairs per mm on film best cases typically 30 for an average great image. <BR><BR>Its been now 6 decades since loons have quoted high line pair per mm numbers with 1:1000 test objects; but few if any really have the adulthood to test at say 1 to 1.6; since then results would be just fair; ie ;like reality of shooting a portrait, scenic, ie a real commercial job that REQUIRES some actual MARGIN; ie one has some design margin so the image is known to work; ie not best caseing all data to give childish fairy tale numbers.<BR><BR> In printing;the inputs we get that are by digital versus film worrywarts are typicially the worst in quality; they want you to scan way beyond what their crappy blurred holds; they have drunk the Koolaid and believe that their 35mm slides holds a fantastic amount of data; when its bettered by a Walmart 3 megapixel P&S<BR><BR>Most folk do NOT drum scan their film. Most folks do no have friends that look like 1:1000 contrast bars unless they are football or hockey refs. <BR><BR>Folks who want an exact megapixel per square cm figure probably are confused about how to make coffee; ie what ratio? :)

@ Bernie West [Frequent poster] , Nov 13, 2008; 09:13 p.m

<p>

<i>I'm not familiar with how the carbon bonds in a diamond.</i>

<p>

No problem, its irrelevant. 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>

Once again, the thrust of my argument is this: <i>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>

This should actually be self evident by now, ref. Rich's example and mine are simple proofs.

<i>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>

 

Once again, I don't care. Like Rishi, I'm not sure why we are talking about this.

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.

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

 

So you've both lost focus. As have I :)

 

Rishi

 

P.S. OK no not really. I'll be back with my diagram when I can get around to it. In the meantime, how come I haven't heard anyone corroborate or challenge my assertion that maybe it's not even the grain that is the elementary image-forming element, but, rather, the filamentous growths (black) that grow outward from a sensitivity centers on the grain? In this view, the grains are there to provide the silver atoms & the sensitivity centers, but in the end, after development and washing away of silver ions, it's just the filamentous growths that remain. Who cares what the grain itself looked like to begin with? (of course, the filamentous growths can only grow inward in a grain, since they can't grow into the gelatin).

 

Attack it, tell me if you like it, etc. etc.

<P>I don't have a whole lot of energy tonight as I'm still fighting a nasty head cold so, again, I'm not going to

try and reply to everything, just select quotes.</P>

<P></P>

<P>Bernie - the microscope I use is a neighbor's. They only live a couple doors down and they're good friends,

but I don't think they would appreciate me coughing and sneezing near their kids. If there's still interest when

I'm well I'll try and digiscope some shots.</P>

<P></P>

<P>I think all these quotes are from Vijay...</P>

<P></P>

<P><i>You also seem to be saying that you can't see anything other than a black grain in a microscope at 400x and

you show that image to prove it - the source content in the image is binary - which means you can draw no

conclusion whatsoever, but that doesn't seem to bother you.</i></P>

<P></P>

<P>That is an absurd claim. There's a range of gray tones in the magnified area. Look at the 20x frame. Yes

there's the black of her pupil and the white of the light in her eye (opposite on the negative of course), but

there's also clearly light, mid, and dark grays forming her iris and skin surrounding her eye. It's obvious that

in print there will be gray tones. The image is most definitely not monochromatic or "binary." By 60x the binary

nature of grain tone (there or not) is evident, but we're still looking at areas which will print in grays.</P>

<P></P>

<P>Yes or no: have you tried studying B&W film under a microscope? I assure you, the most perfectly smooth mid

gray region is the same at sufficient magnification: black specks on clear base. Try it.</P>

<P></P>

<P><i>You do not truly understand the nature of binary, non-linear, switching systems because if you did, you

would even be imagining such a thing.</i></P>

<P></P>

<P>Nobody ever said that film was an example of a complete <i>binary system.</i> So arguing about that is

pointless. Michael Reichmann's statement was that film grains are <i>binary in tone.</i> If they're there,

there's black. If they're not, there's clear. This is obviously true from microscope views.</P>

<P></P>

<P>An important consideration in understanding how tone is formed in film is that they are not binary in size.

Grains grow in proportion to exposure and development time. But a grain, big or small, still appears as black.

Tone is formed by density in film. It is directly measured and encoded in electronic sensors. That doesn't mean

one wins or loses, it's just a description of image structure. And it does explain why digital is so competitive

at resolutions lower than one would assume they would need against film.</P>

<P></P>

<P><i>I've been repeatedly saying that at the visual scale, you may see black specs but there is no information

at that scale that tells you that several black specs are not part of just one grain.</i></P>

<P></P>

<P>The image series I've posted twice explains that the filament structure of a single grain (silver halide

crystal reduced to silver), which is seen under an EM in E, is perceived as a single particle at optical

magnifications. Even at 400x most of those black specks are larger than the average size for a single silver

halide crystal, meaning the speck is more than one grain clumped. The spaces between are also larger than

individual silver halide crystals, so it's hard to imagine that a speck-space-speck sequence could only involve

one crystal.</P>

<P></P>

<P><i>If the grain were a switching system,</i></P>

<P></P>

<P>Nobody ever said it was a switching system, and that is the error in your logic. Too much of this thread,

especially since I last viewed it, has been focused on a strawman, arguments that film could not be a binary

system. Neither a silver halide crystal nor the overall development process is a binary switching system. And

neither Reichmann nor Adams claimed they were. But they don't have to be for the resulting silver to be a single

tone.</P>

<P></P>

<P>Silver is silver. Why would we expect it to assume a range of tones? We wouldn't. So achieving tone using a

single material which is necessarily of a single tone requires changing the density of said material. Does the

filament structure of silver as viewed under an electron microscope matter? Again I ask how a structure that

requires an electron microscope to image could possibly have an impact on viewer perception. And if it does, why

is it not observable at magnifications greater than those for an average print?</P>

<P></P>

<P>Re: "molecular" resolution</P>

<P><i>If you could create a case wherein exactly one AgBr molecule got converted to Ag, and if you had the

equipment to precisely observe this, you could. </i></P>

<P></P>

<P>No you couldn't because an individual molecule/atom is not perceivable. Remember we're talking about a visual

system to be perceived by human eyes under some level of relatively minor enlargement. If you had a precision

system to deposit a single grain of silver or a single dye cloud on a piece of film, and then removed one silver

atom or dye molecule, it would not make any difference in the tone perceived by the viewer, even under extreme

magnification. Therefore you cannot do as Ron did earlier, treat each atom/molecule as a "bit" in a formula and

theorize that film must be able to record some absurd astronomical number of tones.</P>

<P></P>

<P>Heck, under normal enlargement a single grain or dye cloud would not be perceivable at all. You need to have

and change a cluster of the things to impact viewer perception of a detail or tone.</P>

<P></P>

<P></P>

 

<P>Re: Your hummingbird analogy.</P>

<P></P>

<P>I kind of skipped over the posts where this started but I'm going to take a bite at this particular post.</P>

<P></P>

<P><i>This means that on real film, exposed silver grains will immediately turn black (on first contact with

developer), and increasing development time would have no effect.</i></P>

<P></P>

<P>It's not a matter of turning black. It's a matter of silver halide converting to silver in a chemical reaction

which is not instant. The exposure of an individual silver halide crystal, the developer, the temperature, the

agitation, and the time all affect the odds of said silver halide crystal converting at all, and the degree to

which it converts once the reaction has started.</P>

<P></P>

<P>But silver will appear black whether it's a small deposit of silver or a large deposit. Silver is silver.

During the reaction it's not going from "light gray silver" to "middle gray silver" to "dark gray silver" and

then finally "black silver." It's silver. Shine a light behind it and it's opaque, black. During reaction it's

growing in size until, if conditions are right, the entire crystal is converted. That just means you have a "big"

deposit of silver relative to what you would have had if some condition were different (less exposure or time).</P>

<P></P>

<P><i>Try this: take a roll of film and pull it out of the cannister and expose it to direct sunlight for 10

minutes. At this point you should be fairly sure that all mousetraps have sprung with the mice, right? That means

the hummingbirds can't do anything further to spring the traps.</P>

<P></P>

<P>Now keep the film in the developer for its full development time, you should see all black, right? Now go half

development time, you should still see black, correct? I mean, all mousetraps have already sprung. Go for quarter

development time; once again, same result, black. All sprung traps. Same for an eight development time, etc...

which means that at first contact, the film will be developed. Meaning no push or pull can be possible.</P>

<P></P>

<P>Does this really happen?</i></P>

<P></P>

<P>No, but not because silver can be something other than black in this context. As you decrease development time

you decrease the odds that a particular silver halide crystal will begin to react, as well as the degree of

conversion of molecules in said crystal to atoms of silver. The example is pretty extreme (10 minutes of full

sunlight might cause the film to darken before development) so you would have to really slash development time to

go from black to a gray tone over the frame. But if you found a time which achieved this you're not producing

"gray silver", you're decreasing the number of crystals which react and the number which react completely. The

resulting silver deposits are fewer in number and smaller in size, so your density is lower and some light gets

through the frame to your eyes.</P>

<P></P>

<P>But under a microscope you will still find black specks on clear base.</P>

<P><i>P.S. OK no not really. I'll be back with my diagram when I can get around to it. In the meantime, how come I haven't heard anyone corroborate or challenge my assertion that maybe it's not even the grain that is the elementary image-forming element, but, rather, the filamentous growths (black) that grow outward from a sensitivity centers on the grain?</i></P>

<P></P>

<P>This is essentially another way to state Mark and Vijay's opinion. We've been arguing over it forever now ;-)</P>

<P><i>Since were are on this topic....can anyone tell me how many angels can dance on the head of a pin?</i></P>

<P></P>

<P>What you should really be asking is whether angels shoot Canon or Nikon.</P>

<P></P>

<P>And what their opposition shoots ;-)</P>