Wow - read this re: Film versus Digital debate!

[rishij]

Daniel:<i>"Man may be able to direct the arrangement of silver atoms to produce a translucent coating, but this very precise and specific arrangement is not observed to occur in the random, natural silver structures in B&W film."</i>

<p>

This is a very good point. I think the electron reduction process occurs quite stochastically (duh!) at a 'latent site', so AgBr salts are reduced left and right within the crystal, not just along one filamentous thread in one direction separate from another filamentous thread (of the same silver deposit/sensitivity center, mind you) -- separated by a gap large enough to pass visible light. This is unlikely. Which is probably why most filamentous clumps look opaque, and, under the EM, don't seem to have huge gaps anyway.

[bernardwest]

Gentlemen, after much soul searching, I have decided to choose my marriage and job over this thread. Good luck in

further chasing your tails around endlessly, as I believe Vijay will never concede his position. Before I retire to the

sidelines, I thought I might venture to introduce some more worldly numbers into the discussion. I am not one to

have ever fussed over resolution, hence the reason why I don't have much of an inclination to learn the terminology

involved in measuring resolution. So I will keep my calculations simple, if only for the reason that I can't be more

detailed. You guys can ammend, modify, or totally disregard the figures. I only hope it might take the discussion to

a more realistic frame of reference. So here goes (*disclaimer - these figures are somewhat guestimates. You guys

can replace and argue over more accurate figures if you have them):<p>

 

Human hair varies quite a bit in thickness, but can average from about 50 - 120 microns in Caucasians and Asians.

Let's take an average: 85 microns. <p>

 

I choose to assess resolution with the eye 1 metre from a print (whatever it's dimensions). <p>

 

At 1 metre, what sized object can a human discern? I am going to say that a human can discern something half the

thickness of a strand of hair. So I put human resolution at about 40 microns.<p>

 

How big are we going to enlarge a 35mm negative? I am going to say 1 metre in length (I've really got no idea how

large someone would or could enlarge a 35mm neg to, so please substitute more realistic figures if you want). This

is approximately 30x magnification.<p>

 

B&W film grains: Daniel has stated a range of 0.2 - 2 microns. For the sake of some form of agreement, let's say

the smallest grain that can be imaged optically is about the wavelength of light. Therefore we assume a grain size

of .5 microns. 0.5 x 30 = 15 microns. That is the size of a grain in a 1m print.<p>

 

Humans, I have assumed, can discern an object of 40 microns. Therefore about 3 adjacent grains are needed to

become visible to human sight.<p>

 

This, of course, is where it gets ugly. If grains are binary, then only 4 tones (clear, 33%, 66% gray, and opaque) will

be discernable. If individual grains have infinite tonal variation then, well, the 40 micron section of the print could also

have infinite tone (well, at most the maximum number of tones able to be printed).<p>

 

How does this compare to digital? First let's assume a 5 micron pixel size. If we are talking about most dslrs, then

we have the bayer interpolation and the anti-aliasing filter to throw into the mix. So, whilst a dslr pixel is 5 microns, it

could not resolve <b>real</b> detail at this level (These figures would change with a foveon sensor as it ofcourse

doesn't need bayer interp and has no anti-aliasing filter). It's a guestimate but probably in the range of 3 to 6 pixels

would be needed to represent real detail. That's a figure of 15-30 microns. Regardless of the exact figure, as long as

it stays below the human resolving limit of 40 microns, then a dslr will be capable of representing 2^14 tones in a 40

micron area on a 1 metre print.<p>

 

What would film need to represent this many tones. Clearly it would need for it's grains to have infinite tonality. If

they indeed do, then this debate would be over. So far, though, we haven't seen any objective evidence which states

that they do have infinate tonality. And I believe until we get a physicist in here, we aren't going to get an answer by

arguing with each other. If grains are binary, then, well, I think the answer is quite possibly absurd (if I could be

bothered to work it out). <p>

 

So where does this leave us? I don't know. But please try to play with the figures using numbers percievable in the

<b>real world</b> by humans. I'll watch from the sidelines and see where this big mess ends up. It's been very

educational. Cheers, and thanks for a good discussion.

[vijay_nebhrajani]

Rishi: "Which is probably why most filamentous clumps look opaque"

 

I just got back from work after eighteen grueling hours resolving a problem. I have no energy left right now, so

I'll take the thread up tomorrow.

 

But I just wanted to comment on Rishi's statement.

 

You got that right. Because of the word "most". There will be others, that never achieved the dimensions needed

to make them visible under a microscope, or remained thin enough to act like a thin film. This is merely a

consequence of the random nature of formation of the silver clumps. Like all chemical reactions, the reduction of

AgBr will follow some rate (I forget the calculations for rate of reactions) but for developers, we know it is in

the order of several minutes, allowing you to increase/decrease the time to adjust contrast and effective film

speed. (Actually this last point should trigger some thoughts in your mind, but we'll talk later.)

 

And because we are talking a slow rate, you'll have some random mixture of macroscopically visible silver specks,

some smaller ones, and some really tiny or thin ones. A lot of this could happen inside a single crystal as it

gets reduced, since it has multiple sensitivity sites, randomly distributed impurities, odd crystal shape etc.

And as Rich Evans tried to point out several times, there will be diffraction effects as light bends around

silver specks and forms fringes - even these contribute to a variation of tone - meaning that even if you had

black specks on a clear film and you could print these on paper, diffraction alone would ensure that instead of

printing black specks on a white paper, you'd print black on very, very light gray. That is how it affects tone

(adversely, in this case, reducing contrast).

 

So a what silver is left behind by a single crystal has the ability to form a vast variety of shapes and sizes.

As far as tone generation is concerned, the situation is simple. Large specks of silver will obviously contribute

the most to tonality at the macro level - but those other unmentionable effects - such as partially transmissive

silver specks, diffractive effects etc will fine tune the tonality; like increasing Dmax or reducing clumpiness

(densitometric granularity measurements) for midtones - or reducing sharpness or increasing base fog, for

diffractive effects.

 

Remember that much tinier silver crystals are also added in layers to film - these layers, because they have much

smaller crystals (and consequently MUCH LOWER FILM SPEED) will be grossly underexposed for any given exposure at

the film's rated speed (which like the resolution limit, is determined by the largest crystals in good part -

yes, there are other

factors for efficiency, but grain size is a huge one). I mean that if you exposed correctly for the smallest

crystals, the huge crystals would be overexposed and simply black. You expose for the largest crystals - thereby

underexposing the smallest ones, which would then largely get washed away, right? So why even bother to add extra

layers, making a thick film and reducing sharpness?

 

Because whatever silver does get left behind, helps to increase Dmax (i.e., enhance the tonal range) and smoothen

out other midtones. How can this be possible with silver specks from really tiny crystals that are largely

underexposed, leaving behind silver deposits too tiny to be seen with microscopes? Yet, we know it is possible;

we know it is actually DONE by companies like Kodak and Ilford.

 

You should ask - since those large, macroscopic grain particles that do get seen with a microscope are much

larger compared to those teeny weeny translucent silver specks, wouldn't the effects of those specks be too small

to make any difference?

 

Well, if you call extending the dynamic range of film too small... or smoother midtones too small... Besides, in

people's minds such effects are not observable under a bright field microscope at 400x so they obviously can't

affect perception of "brighter whites, blacker blacks and smoother midtones". That must, in their minds, be an

advertising gimmick anyway. (And I am sure the advertisers can't exaggerate ;-)

 

So you should ask yourself - you have these soccer balls lying around on the sand, with a thin layer of sand

above them or below them. You're seeing this from a hundred feet away and thinking there is no sand, since it is

all smooth anyway and you can't see the sand particles. So all visual phenomena from a thousand feet away must be

explainable by the arrangement of those soccer balls - the sand can't play any part, even if the sand particles

existed, because it wasn't visible at 100 feet, so at 1000 feet it will make an even lesser difference. But those

sand particles may be reflecting light back at you better than say, rubble. But since you couldn't see them from

100 feet away, and normally you anyway don't go nearer than 1000 feet... they might as well not exist.

 

This is like not seeing the moss for the trees.

 

But you get what I mean.

 

At this point I feel so incoherent that I'd better crash. See you guys later. This debate is addictive. Man. I

thought I'd crash 45 mins ago. But here I am.

[vijay_nebhrajani]

Bernie: "I believe Vijay will never concede his position"

 

I will absolutely do so when I'm convinced that I'm wrong. At this point I'm just not. Its not like I have been right about everything in my entire life. If you knew how much money I lost in the 2000 tech crash, you'd puke.

[danielleetaylor]

<P><i>You got that right. Because of the word "most". There will be others, that never achieved the dimensions

needed to make them visible under a microscope,</i></P>

<P></P>

<P>Which means they cannot impact visible perception <b>at all.</b> You cannot seem to grasp this point. To claim

that there is a thing which is visually observable at 10x but not at 400x is absurd. <b>Magnification does not

work in that direction.</b></P>

<P></P>

<P><i>or remained thin enough to act like a thin film.</i></P>

<P></P>

<P>I would question whether this is even theoretically possible given the fact that it's not observed. A

physicist more familiar with the interaction between matter and light would have to check me on this, but I would

guess from the random, 3D nature of grain shape and silver formation that you effectively never get a silver

formation of the proper dimensions to appear translucent in B&W film. I don't think you realize just how precise

real world examples of such coatings are, or how little difference there is between these delicate designs and

either full transparency on one end or full blocking on the other.</P>

<P></P>

<P>But, again, even if they occurred occasionally, they clearly are not the basis for tone.</P>

<P></P>

<P><i>Large specks of silver will obviously contribute the most to tonality at the macro level - but those other

unmentionable effects - such as partially transmissive silver specks, diffractive effects etc will fine tune the

tonality;</i></P>

<P></P>

<P>If they fine tuned the tonality at 10x, they would be even more readily observed at 400x.</P>

<P></P>

<P><i>Because whatever silver does get left behind, helps to increase Dmax (i.e., enhance the tonal range) and

smoothen out other midtones. How can this be possible with silver specks from really tiny crystals that are

largely underexposed, leaving behind silver deposits too tiny to be seen with microscopes?</i></P>

<P></P>

<P>If they're "underexposed" they won't leave behind any silver. That's actually the point. If large crystals are

exposed and develop out but small crystals between them don't hit that threshold and wash away, you have an

effective halftone pattern for a very bright area, i.e. you have some detail in a very bright area. If all

crystals in all layers were of the same average large size, the film would have less DR. (Didn't we cover this

eons ago when you asked what would happen with a grid of identical crystals?)</P>

<P></P>

<P><i>Besides, in people's minds such effects are not observable under a bright field microscope at 400x so they

obviously can't affect perception of "brighter whites, blacker blacks and smoother midtones".</i></P>

<P></P>

<P>These translucent gray grains you believe exist are also not observable under a grain focuser. Are you going

to suggest that the enlarger renders them as opaque yet they still must exist and influence the final print? The

problem there is that they're not observable in very large prints from small format film either. (You can print

35mm to the point that it breaks down in terms of tonality, i.e. up close you see grain clumps and the illusion

of gray is broken, something that shouldn't be possible if tone is formed by gray grains.) So are they both

observable and not observable on the same print at the same time?</P>

<P></P>

<P>I have to admit I have not tried this combination, but if I magnify the center of a 35mm frame, as much as

possible using an enlarger, onto 8x10 paper, then study that print under a loupe, will I then see these gray

grains? Where are these elusive gray grains that they cannot be found yet they supposedly influence our

perception of gray tone in a final print? Am I the only one who thinks such an imaging element is absurd?</P>

<P></P>

<P><i>So you should ask yourself - you have these soccer balls lying around on the sand, with a thin layer of

sand above them or below them. You're seeing this from a hundred feet away and thinking there is no sand, since

it is all smooth anyway and you can't see the sand particles. So all visual phenomena from a thousand feet away

must be explainable by the arrangement of those soccer balls - the sand can't play any part, even if the sand

particles existed, because it wasn't visible at 100 feet, so at 1000 feet it will make an even lesser

difference.</i></P>

<P></P>

<P>False hypothetical and false analogy.</P>

<P></P>

<P>The fault in the hypothetical: a thin layer of sand which is as large as the soccer ball arrangement in

height/width will be observable at the same distances where the soccer balls are observable, just not as discrete

particles.</P>

<P></P>

<P>The false analogy part: as you use instruments to magnify the scene the sand will become more apparent, more

easily observed, until finally its structure as discrete particles is clearly seen.</P>

<P></P>

<P>But that's not what you're suggesting. You're suggesting that the sand layer will be observable at 100 feet

but suddenly disappear upon instrument magnification. This would be absurd.</P>

<P></P>

<P><i>I will absolutely do so when I'm convinced that I'm wrong.</i></P>

<P></P>

<P>A scientific theory is falsifiable (or should be). So what observation would be required to falsify your

theory?</P>

<P></P>

<P><i>At this point I feel so incoherent that I'd better crash. See you guys later. This debate is addictive.

Man. I thought I'd crash 45 mins ago. But here I am.</i></P>

<P></P>

<P>And I make fun of my friends who play World of Warcrack. If they only knew...</P>

 

[rich_evans]

DLT: And I make fun of my friends who play World of Warcrack. If they only knew...

 

LOL! Could you imagine if this were a political debate?

 

Oh yeah - remember we were discussing the chemical make-up of the grains? Well x-ray elemental analysis of the post-

development features shows no halides remain - only silver (I had promised to post this on Friday but ran out of time - see

spectrum below).

 

As much as I want to continue working on this interesting little project today, I unfortunately have some other priorities -

but I'm keeping my samples and will revisit them soon.

 

And I'd like to try to find a good substrate to evaporate or sputter some gold onto and get a look at what the film actually

looks like.

 

Hope you all enjoyed - or were at least intrigued - with the images.

 

--Rich<div></div>

[rich_evans]

Oh - and for anyone interested in the techie/scientific hardware used to get the SEM images, this is my 'camera'.

 

--Rich<div></div>

[diegobuono]

To Dave Wyman who wrote:

You've been living in a cave with Bin Laden? No, even he has a digital camera.

 

Dave I have'nt gone digital, actualy I leave in a cave as you can see..... may be this is the reason I havent gone

digital :-)

 

Anyway, I don't live with Bin Laden! :-)<div></div>

[stephen_pitts]

Rich,

 

Definately like the set-up. I'm always curious about what one can discover in the worlds of the extremely small and

the extremely large (went to Caltech undergrad and enjoyed the use of both an electron microscopes and very large

telescopes). Anyhow, thanks for putting so much time and resources into this log. Its most appreciated.

 

Vijay,

 

Been there on the internet ($$$) loss. Now experiencing the banking loss... Its like being in Dark City. I think your

overall estimate of 35 mp for 35mm is probably right on the money. Of course, there are lots of other factors in the

film versus digital comparison. But despite the length of the piece, the stongly worded arguments on each side, this

has been the most thoughtful and (well) argued debate on the subject. Including, of course, Armando's comment

of "just look at it to compare the two" (in the world of audio, the ear is a much more particular and perceptive

instrument than lab bench equipment and so an analytical debate of this nature is almost pointless -- you can only

judge by listening). Your analysis bears much fruit and one would hope that this thread would be cited to simply

establish the rough level of equivalency in information content between the two. By the way, the 35 mp nicely

matches to the diffraction limit of the very, very best lenses available on the market (you would need to build huge

lenses to get any better). So the different worlds all begin to converge on some common figures and everything

begins to make sense. Anyhow, thanks so much for providing so much to the thread (but please calm down a bit) --

we'd hate for you to be so frustrated as to give it up. A truly great contribution to this most relevant and important

subject.

 

Cheers,

 

Steve

[vijay_nebhrajani]

<i>Oh - and for anyone interested in the techie/scientific hardware used to get the SEM images, this is my 'camera'.

<p>

--Rich

</i>

<p>

Could I get that on fleabay? I'm sure that will make me a better photographer. My portraits will just sizzle.

[vijay_nebhrajani]

Scratch that - my portraits will just GLOW.

[vijay_nebhrajani]

<i>False hypothetical and false analogy.

<p>

The fault in the hypothetical: a thin layer of sand which is as large as the soccer ball arrangement in

height/width will be observable at the same distances where the soccer balls are observable, just not as discrete

particles.

<p>

The false analogy part: as you use instruments to magnify the scene the sand will become more apparent, more

easily observed, until finally its structure as discrete particles is clearly seen.

<p>

But that's not what you're suggesting. You're suggesting that the sand layer will be observable at 100 feet but

suddenly disappear upon instrument magnification. This would be absurd.

</i><p>

Wrong, wrong and wrong.

<p>

When a thin layer of sand as large as a soccer ball is present, <i>the soccer balls are present in the same

relative density</i> - more soccer balls, more densely packed. Both form by the same process - its not like you

can make soccer ball sized sand layers, but not have soccer balls present. Those soccer balls will make the sand

impossible to see. The analogy holds but I did forget to mention that the sand and soccer balls are present in

equal relative density. But wait, that is the nature of the silver formation, isn't it? Or are you back to

suggesting that soccer balls would suddenly form from nothing, but sand wouldn't? (the binary, switching silver

speck argument - that a crystal of silver halide would suddenly change state to silver, without going through any

intermediate state?)

<p>

You didn't get the analogy part then. The 100 ft equated to 400x magnification. And as you get closer, and

observe with better and better instruments, the "sand" does get magnified and visible, as in electron

micrographs. Just as at 1000 ft (naked eyes) there are no soccer balls visible (but they really are there,

clearly visible at 100 ft) - at 100 ft (optical bright field microscope) there is no sand visible (but it is

there, clearly visible with instruments).

<p>

Quite the contrary - I'm suggesting that the sand layer is visible as discrete particles at 100,000x and affects

density at 400x and lower magnifications. Where is the problem with that? You are saying it won't affect density

at all. And that is not absurd?

[don_harper_the_edge]

I see a lot of discussion about the techical aspects of digital versus film, but unless I've missed it nothing about the BUSINESS of photography. The original poster talks about selling stock photography. This market has undergone a seismic shift with the advent of digital photography and the disappearance of many of the smaller stock agencies.

Also, even more important is the devaluation of stock images. He will find it very difficult to create images for stock agencies which rely on submission of digital files on-line from film, scanned and than uploaded. The economics will not support this workflow. Is this a generalation? Yes, there are a few artists creating really unique images that can demand a high enough fee to make this work, but for the most part they are selling through galleries or boutique services. The typical stock agency won't provide enough profit to shoot medium format, pay a lab to scan and than upload the images.

Much has changed since his working days, and he needs to relearn and evaluate what he can sell.

There are a lot of news agency photographers being laid off that create amazing images also struggling to stay in photography with stock sales.

I wish him luck.

 

Don Harper

http://www.theEdgePhotography.com

http://www.arlington-photographer.com

[danielleetaylor]

<P><i>When a thin layer of sand as large as a soccer ball is present, the soccer balls are present in the same

relative density - more soccer balls, more densely packed. Both form by the same process - its not like you can

make soccer ball sized sand layers, but not have soccer balls present. Those soccer balls will make the sand

impossible to see.</i></P>

<P></P>

<P>You've completely lost me on your analogy. I'm sorry, I don't see the relevance to anything we are discussing.

I <i>thought</i> that you were trying to say a layer of sand would impact the view of the soccer balls at a

distance even if the person didn't realize the structure of the sand as discrete particles, like a dust storm.

(True, but then my complaints apply.) But now I'm not sure what you're trying to demonstrate with the analogy.</P>

[danielleetaylor]

Rich,

 

I was hoping to someday get the Canon MP-E 65mm macro lens which can go to 5x. But now, somehow, it just doesn't seem all that powerful ;-)

[rich_evans]

Vijay,

 

If you've got a spare $850,000 just laying around plus an extra $22,000/year for a service contract, and an infinite amount of patience, (oh yeah, and I've got a 2nd equally elaborate system in the next room that's used only by staff scientists and for which I'm also responsible) then you can get one for your basement. Otherwise you can get this:

 

http://cgi.ebay.com/Complete-Scanning-Electron-Microscope-SEM-ISI-40_W0QQitemZ120331035473QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item120331035473&_trksid=p3286.c0.m14&_trkparms=66%3A2%7C65%3A3%7C39%3A1%7C240%3A1318

 

Cheers.

 

Rich

[john_castronovo]

Guys - silver grains themselves don't make up a silver image but rather it is how LIGHT plays with the silver

that makes the image.

 

This sounds more simple than it is, but the action of light has everything to do with whether or not a crystal is

opaque or some shade of gray, either to the eye, the scanner or whatever else is looking at it. Silver crystals

are three dimensional and are layered and light isn't just collimated and focused like an electron microscope

when an image is created from the emulsion. The old adage that the whole is greater than the sum of the parts is

more true of silver grains than pixels.

[vijay_nebhrajani]

John: "Guys - silver grains themselves don't make up a silver image but rather it is how LIGHT plays with the silver that makes the image. "

 

That is exactly what I have been saying all along: just want to add to your statement: "regardless of size of the silver specks".

 

Daniel is arguing (or at least I think he is) that once the silver grains (or "silver specks", to distinguish them from unprocessed silver halide crystals, which are also called grains) are smaller than can be seen through an optical microscope, light just won't play with those silver specks, so they couldn't affect tone (shades of gray) in the final print.

[vijay_nebhrajani]

"If you've got a spare $850,000 just laying around plus an extra $22,000/year for a service contract, and an infinite amount of patience, (oh yeah, and I've got a 2nd equally elaborate system in the next room that's used only by staff scientists and for which I'm also responsible) then you can get one for your basement. "

 

Rich, yeah - its just the infinite amount of patience I don't have. But wait, I'm participating in this thread - so it appears that I have the patience too. Drat. Now I have to come up with a million bucks for a camera. Won't be easy to hide that from the wife, I suppose. But if it makes my pictures glow, like Leica does, then whats a million here, a million there?

 

Ha, ha.

[bernardwest]

<i>The old adage that the whole is greater than the sum of the parts is more true of silver grains than pixels.</i><p>

 

What's the evidence for this?

[danielleetaylor]

<P>Vijay,</P>

<P></P>

<P><i>Daniel is arguing (or at least I think he is) that once the silver grains (or "silver specks", to distinguish them from unprocessed silver halide crystals, which are also called grains) are smaller than can be seen through an optical microscope, light just won't play with those silver specks, so they couldn't affect tone (shades of gray) in the final print.</i></P>

<P></P>

<P>Why won't you address the absurdity of your suggestion that something can be observable at 10x but not 400x? How does that work? To suggest this is to suggest every law governing vision and magnification is wrong. If something cannot be observed under an optical microscope it is not going to be seen in a print. If something is not "playing with" enough light to produce observable effects at 400x, it sure in the heck isn't going to produce observable effects at 10x.</P>

<P></P>

<P>How do you ignore or get around this? It is as if you based your theory on 2 + 2 = 5, and I keep pointing out to you that 2 + 2 = 4, but you're not getting it.</P>

<P></P>

<P>As I've said, even if it was possible for silver specks to grow in such a way that they possessed some translucent properties, they are never observed to do so. If they formed the basis of any gray tones in B&W photography, they would have to occur with enough frequency to be observed. There is no such thing as disturbing light in such a way that there are observable effects at 10x but not 60x or 400x.</P>

<P></P>

[vijay_nebhrajani]

Daniel: "You've completely lost me on your analogy. I'm sorry, I don't see the relevance to anything we are discussing. I thought that you were trying to say a layer of sand would impact the view of the soccer balls at a distance even if the person didn't realize the structure of the sand as discrete particles, like a dust storm."

 

Yes, and what I was saying was that in order for you to observe a soccer ball sized arrangement of sand you'd need a condition wherein the soccer balls were absent. If the soccer balls were present in quantity, they'd obscure the view of the sand arrangements. Correct?

 

To talk about film - to get a density of those tiny silver specks that you could observe through a 400x microscope, you'd have to expose the film enough - but this "enough" would also create larger silver specks, which would make the smaller ones harder to see. That does not prove that the smaller specks don't exist, or that they wouldn't attenuate light also, playing their part in the generation of tone.

 

I'll admit that my analogy to sand and soccer balls doesn't illustrate the actual situation very well (and I wouldn't have put it forward if I weren't so zoned out last night) because of transmissive vs. reflective viewing (sand = reflective, bright field microscope = transmissive).

[vijay_nebhrajani]

<i>Vijay: Go put a neutral density filter in your microscope between the film and the objective. That neutral

density filter has tone, right? See the grain through the microscope. Do you see opaque silver specks on a gray

background because of the ND filter? No.

<p>

Daniel: Yes. Heck, the background without a ND filter doesn't look "white" because of the effect of the film

base/gelatin. With one that background would be even more gray. But you are right that the silver specks will

remain opaque.

</i>

<p>

<b>This is the fundamental error you are making, Daniel.</b>

<p>

Try a couple of simple experiments.

<p>

1. Darken the room in which your computer is. Take an SLR camera and point it at this screen. Focus on the

screen. All black words on white? Good.

<p>

Open the aperture of the lens to the maximum and activate the depth of field preview lever.

<p>

No change? Good.

<p>

Now close the aperture by a stop and activate the depth of field lever. Let your eye adjust.

<p>

What do you see? Black words on a gray background?

<p>

Do this with a lens that has a wide max aperture (1.4/1.8) if you have one. Also it would help if the computer

screen occupied the entire field of view through the viewfinder.

<p>

2. Take a negative that is expendable and has a large area of uniform mid gray tone. Cut out some small pieces

from that mid gray area and place them on a light table so they don't overlap. Darken the room, let your eyes adjust.

<p>

What do you see?

<p>

Gray specks on the light table?

<p>

<b>Please do these experiments</b> and tell me what you see. This is quite important, because you are missing the

<i>single most important detail</i> that is occluding (don't mind the pun) your thinking.

<p>

Lets discuss further after you have results from the experiments.

[bernardwest]

Daniel.. don't buy into this rubbish. Tell him to do my reduction ad absurdum thought experiment first (and in doing so, playing by the rules he has set all along), and then you (we) will talk further.

[bernardwest]

<i>Vijay Nebhrajani , Nov 12, 2008; 09:46 p.m.<p>

 

You could argue about the physical and chemical processes till the cows came home, but you can't escape logic; if you want to disprove me, all you have to do is show the error in my logic.</i>