Square Grained film

Ektagraphic · May 31, 2012

Would it be possible for film to have square grains? (AFAIK, it does not, but I could be looking like an idiot right now). If so, would remotely look like it has p-x-l-s rather than traditional grain?

Patrick

Terry Christian · May 31, 2012

I would venture to say that it would probably look like most other T-grained film. When we refer to visible "grain" on film, we're actually seeing large clumps of silver grains, not individual grains themselves. I recall someone making that same point in a thread here recently.

holmburgers · May 31, 2012

If I'm not getting in over my head, I believe that silver-halide crystal formation is governed by the pAg of the solution in which it is formed, in addition to the soluble salts & other things (silver-halide solvents, etc.) present.

According to the famous graph that's posted hither and thither, there is no square grain stage. And like Terry says, they'd be so small that you wouldn't really see them as individual squares anyway.

Nicholas Lindan · May 31, 2012

A 'grain' of developed silver looks like nothing so much as a bit of steel-wool scouring pad. The undeveloped silver halide crystal is either a cube (sometimes with itty-bitty cubes at the corners) [traditional emulsion] or a flat triangle with the points chopped off [t-grain 'tabular' emulsion]. The action of the developer is to extrude a filament of metalic silver from the active site on the exposed crystal. The shape of the developed silver filament has little, if anything, to do with the shape of the silver halide crystal.

segedi · May 31, 2012

Just curious as to why you'd want that? And wondering if moire would be an issue.

Ian Grant · May 31, 2012

A grain of Silver halide isn't like a Pixel there can be more than one development site.

Ian

holmburgers · May 31, 2012

Nicholas Lindan said:
The shape of the developed silver filament has little, if anything, to do with the shape of the silver halide crystal.

Great point!

Ian Grant · May 31, 2012

holmburgers said:
Great point!

The shape of the crystals does have an effect on how they stack together in an emulsion, the neater they'll pack the finer the potential grain after processing.

Ian

lxdude · May 31, 2012

Pixels don't have to be square. They could be arranged in a way that would cause them to be hex-shaped for example, and that would be what you would see on your monitor- a honeycomb instead of a grid.

The individual "grains" are particles which are extremely small-- nanometer scale. What you see as grain is a random variation in density of developed particles, as viewed through the entire emulsion. It is a visual phenomenon, rather than a physical one, as it would be if it were actual clumps.

Gerald C Koch · May 31, 2012

One of the unfortunate things about Nature is that she gives us what she wants and not what we desire. Some years ago there was a serious attempt to breed chickens who would lay square (actually cubical) eggs. Such an egg would be ideal for shipping. Ma Nature didn't like the idea and neither did the chickens.

Photo Engineer · May 31, 2012

Ektagraphic said:
Would it be possible for film to have square grains? (AFAIK, it does not, but I could be looking like an idiot right now). If so, would remotely look like it has p-x-l-s rather than traditional grain?

Patrick

Silver halide crystals are stacked in film in 3 dimensions and are themselves 3 dimensional objects. Pixels are not stacked in 3 dimensions but instead are manufactured in a 2 dimensional array on a substrate. Thus a pixel is square but one of the emulsions in Ektar 100 is a cube, and each cube is far smaller than a pixel and each cube in the film are stacked top to bottom and left to right in a random patter of billions of cubes. In fact, for every 108 mg of silver in film, there are 6.023 x 10^20 atoms of silver. There are about 300 mg of silver in ever square foot of film.

Silver halide crystals come in virtually every geometric shape including cubes, octahedra, pyramids, and etc. The pAg at the time of manufacture governs the form. I describe this in my book.

The developed silver can be in the form of filaments, tablets, and a variety of other shapes depending on the developer. This is shown in Haist for example, with photomicrographs.

So in a way, yeah, films have squares! Only they are better, they are cubes.

PE

KenS · May 31, 2012

Gerald C Koch said:
One of the unfortunate things about Nature is that she gives us what she wants and not what we desire. Some years ago there was a serious attempt to breed chickens who would lay square (actually cubical) eggs. Such an egg would be ideal for shipping. Ma Nature didn't like the idea and neither did the chickens.

Actually.... there are two other reasons

First.... The shell would not be as 'strong'

Second... The hen's cloaca would close with either a 'bang' or a 'clap'....

Can you imagine the noise living close by a commercial 'egg factory'. The 'farmer' would not be able to take any afternoon naps.

Ken

lxdude · May 31, 2012

Gerald C Koch said:
One of the unfortunate things about Nature is that she gives us what she wants and not what we desire. Some years ago there was a serious attempt to breed chickens who would lay square (actually cubical) eggs. Such an egg would be ideal for shipping. Ma Nature didn't like the idea and neither did the chickens.

They went about it wrong. First they have to come up with a square chicken; the eggs will follow.

Square Grained film

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