Film Grain

Film grain is the random, sand-like texture you see in a photograph made on film. It comes from the light-sensitive silver crystals in the film’s emulsion, and it is part of how film records a picture at all: the image is built from millions of tiny specks of silver (or, in color film, tiny clouds of dye), so when you enlarge it far enough, you start to see the specks instead of the picture.

Grain matters because it sets how much a film negative can be enlarged before it looks rough, it changes with almost every choice you make when you shoot and develop film, and it has become a look in its own right, one that people now add to digital photos on purpose. This page explains what grain physically is, what makes it finer or coarser, how it differs from digital noise, and when it helps a photo.

What you are really seeing: clumps, not single crystals

Film is a clear plastic base coated with an emulsion: gelatin holding billions of silver halide crystals. Each crystal is tiny, roughly a tenth of a micrometer to a couple of micrometers across. Even the biggest are far too small for your eye to see in any normal print.

When light strikes a crystal, it leaves a small invisible change called a latent image. The developer then turns every exposed crystal into a speck of black metallic silver, and the fixer washes away the crystals that were never exposed. Bright parts of the scene become dense patches of silver on the negative; dark parts stay nearly clear.

The texture you call grain is not those single specks. The emulsion has depth, so crystals sit at many levels, and when you look through the film the specks at different depths overlap and merge. Because the crystals are scattered at random, some spots end up with more silver than the average and some with less. Those random clusters, much larger than any one crystal, are what you see as grain. This is also why grain looks irregular rather than like a neat pattern: there is no grid, only chance.

Color film works the same way up to development. Then, as the developer turns exposed crystals to silver, it also reacts with chemicals in the emulsion to form dye. Each developed crystal leaves a soft cloud of colored dye around it, and the silver itself is bleached away. Dye clouds have soft edges, which is why color negative grain tends to look smoother than the crisp, gritty grain of traditional black and white film. A few black and white films are made the color way (they are processed like color negatives) and share that soft, dye-cloud grain.

Why faster film is grainier

A film’s speed, its ISO rating, is mostly a question of crystal size. A bigger crystal is a bigger target: it is more likely to catch the few photons it needs to become developable, so a film made of bigger crystals needs less light. The price is that each developed crystal leaves a bigger speck of silver, the clusters get bigger, and the grain gets coarser. A slow film of fine crystals needs more light and gives smoother tones and finer detail. That trade, sensitivity against smoothness, runs through the whole history of film.

Tabular crystals, often called T-grain, were the biggest change to that trade. Instead of chunky, roughly cubic crystals, the emulsion is made of thin flat plates that lie parallel to the film surface. A flat plate presents a wide face to the incoming light for the amount of silver it contains, so it is about as sensitive as a much bulkier crystal while forming a finer image. The emulsion layer can also be thinner, which keeps the image sharper. Films built this way give finer grain than traditional films of the same speed, though they tend to be less forgiving of sloppy development.

Need more speed than the film in your camera? Pushing film rates it faster and develops it longer, and grain is one of the things you pay with.

Granularity and graininess: the measured and the seen

Two words get used for grain, and they mean different things.

• Granularity is a measurement made on the film itself. A lab instrument scans a patch of evenly exposed, developed film through a tiny circular opening (48 micrometers across is the usual standard) and records how much the density wobbles from spot to spot. The figure film makers publish, RMS granularity, is that wobble multiplied by 1,000, measured where the film has a density of 1.0. A lower number means finer grain, and because the test is standardized, the numbers can be compared from one film to another.
• Graininess is what you see when you look at a print or a screen. It depends on the film’s granularity, but also on how much the picture was enlarged, how far away you stand, the tone and detail of the subject, and how the print or scan was made. One film maker publishes a print grain index for its color negative films that bakes in a set print size: on that scale, 25 is roughly where most people start to notice grain at all, and a change of about 4 is the smallest difference most people can see.

The practical point is that grain is never a fixed property of a photo. The same negative can look smooth as a small print and gritty as a big one. When people say a film “has fine grain”, they mean its granularity is low, so it stays smooth to larger sizes.

What makes a frame look more or less grainy

Speed and crystal shape are set when the film is made. Everything below is in your hands.

Factor	Finer looking grain	Coarser looking grain
Film speed	Slower film, finer crystals	Faster film, bigger crystals
Exposure (negative film)	Full exposure, shadows well recorded	Underexposure that is brightened later
Development	Normal time and temperature, a fine-grain developer	Pushing, overdevelopment, sudden temperature swings
Frame size	Bigger negative, less enlargement	Smaller negative, more enlargement
Subject	Busy detail and texture that hide it	Large even midtones: sky, skin, plain walls
Scanning and editing	Gentle sharpening, a scan matched to the grain	Heavy sharpening, added contrast, grain aliasing
Viewing	Small print, normal viewing distance	Big print seen close, or a scan at 100 percent

Exposure

On negative film, underexposure is the most common cause of a grainy frame. The shadows get too little light to build up much silver, so they are thin on the negative, and when the lab or your scanner lifts them to a normal brightness, it lifts the randomness with them. Giving negative film its full exposure, or a little extra, keeps shadows dense enough to look smooth. Slide film has almost no room for error either way, so the cure there is accurate exposure, not extra. Old film is a special case: expired film gains fog and loses speed, and both make it grainier.

Development

Longer or hotter development grows the silver clusters and raises contrast, and both make grain stand out. That is why a pushed roll looks grittier than the same film developed normally. Developers differ too: some contain a mild silver solvent that softens the edges of the grain, and others are designed for edge sharpness and make each grain crisper and more visible. A big temperature jump between baths can wrinkle the emulsion into a coarse crazed pattern; that is reticulation, a different thing from grain, though it is easy to mistake for it. If you develop film at home, steady times and temperatures are the simplest grain control you have.

Enlargement and frame size

Grain grows with enlargement in a straight line: enlarge the negative twice as much and every cluster prints twice as big. That makes frame size one of the biggest grain controls of all. Here is how much each common format must be enlarged to make a print 300 mm (about 12 inches) on its long side, using the long side of the frame:

Format	Frame long side	Enlargement for a 300 mm print	Grain size compared with 35mm
Half frame	24 mm	12.5x	1.5 times bigger
35mm	36 mm	8.3x	the same
6×4.5 (120 roll film)	56 mm	5.4x	0.64 times (about two thirds)
6×7 (120 roll film)	70 mm	4.3x	0.51 times (about half)
4×5 sheet film	about 120 mm	2.5x	0.30 times (under a third)

So the same film shot on 4×5 sheet film prints with grain less than a third the size of 35mm at the same print size. This is a big part of why medium format and large format negatives look so smooth, and why the half-frame cameras that squeeze two pictures into each 35mm frame show grain sooner.

Scanning

A scan can show more grain than the film really has. When a scanner’s pixels are close to the size of the grain clusters, the two patterns interfere and produce a harsher, clumpier texture than an optical print of the same negative. This is called grain aliasing. Scanner sharpening and extra contrast make it worse. If your scans look much grittier than prints from the same negatives, turn off sharpening at the scan stage, judge the grain at the size you will actually use the picture, and compare a scan at a different resolution.

Digitizing your own negatives? Scanning film negatives covers resolution, light sources and sharpening step by step.

Grain on black and white, color negative and slide film

Each kind of film shows grain in its own way. Traditional black and white film has the most visible, sharpest-edged grain, since its image is the silver itself; at higher speeds the grain is a large part of its character. Color negative film turns silver into soft dye clouds, so its grain is gentler, and it tolerates overexposure well, which gives you an easy way to keep it clean. Slide film tends to have fine grain for its speed, but it is a positive: what you see on the film is the final picture, nothing is lifted or corrected afterward, and underexposed slides go dark rather than grainy. For how particular films compare, see film stocks compared.

Want to check what you know about different films? Try the analog and film stock quiz.

Film grain and digital noise are not the same thing

A digital camera has no grain. Its sensor is a grid of photosites, and the speckle you see in a high-ISO or brightened digital photo is noise: mostly the natural randomness in how many photons each photosite happened to catch, plus a little from the electronics. People call it “grain” all the time, and the two look alike from a distance, but they differ in ways that matter.

• Where it lives. Digital noise is tied to the pixel grid and is worst in the shadows, where the least light was captured. Film grain has no grid, and on a print it is usually most visible in smooth midtones.
• Color. Digital noise often includes color noise: red, green and blue blotches in areas that should be neutral. Black and white film grain has no color at all, and color film grain is soft dye, not blotchy pixels.
• Shape. Noise comes as pixel-sized specks on a regular grid, so it averages away quickly when you reduce a big file. Film grain comes as irregular clusters of many sizes, set in the negative, so it grows with the print and has no grid to give it away.

The parallel is real, though. Raising ISO on a digital camera trades smoothness for sensitivity, just as choosing a faster film does. In this pair, see whether you can tell which digital photo was shot at the lower ISO.

Which photo was shot at a lower ISO?

A B

Seeing speckles in a digital photo and want to know where they come from? Why are my photos grainy walks through each cause and the fix.

Grain as a look

For most of film’s history, film makers treated grain as a flaw to be reduced, and slower, finer films kept arriving. Photographers did not always agree. Grain does several useful things:

• It adds apparent sharpness. A fine, crisp texture gives the eye small edges to lock onto, so a slightly soft picture can look sharper with grain than without it.
• It hides banding. A random texture breaks up the visible steps in a smooth gradient such as a clear sky, the same trick printers call dithering.
• It carries mood. Heavy grain says rough, fast and close to the moment. Daido Moriyama built a whole way of seeing on it: grainy, blurred, out-of-focus pictures of Tokyo streets, printed hard and dark, where the grain is part of the meaning rather than something to apologize for.
• It moves in motion pictures. Every frame of movie film has its own random crystals, so the grain changes 24 times a second and seems to shimmer. That living texture is a large part of what people mean by the “film look” in cinema, and it is why a single grain pattern frozen over moving digital footage looks wrong.

That is why grain is now added to digital photos and footage. Good simulated grain follows the same rules as the real thing: it is sized for the final output, it is strongest in the midtones and gentler in deep shadow and bright highlight, it has no color in a black and white image, and it is random rather than a repeating tile. Add it last, at the final size, after any resizing and sharpening, or it gets smeared or exaggerated. The grain photo at the top of this page shows the idea: a soft out-of-focus background that would otherwise be a flat smear gets a gentle texture.

Want that texture on your own digital files? How to add film grain to digital photos goes through the settings slider by slider.

Grain is not right for every picture. Where the point is fine detail, as in most product, architecture and big landscape prints, it gets in the way. And grain that looks right on a phone screen may be far too strong in a large print, because the print enlarges it. Grain is one kind of texture in a picture; decide whether you want it the way you decide about the rest.

Common mistakes and misconceptions about film grain

• Thinking each speck of grain is one crystal. Single crystals are far too small to see. What you see is random clusters formed where crystals at different depths overlap.
• Calling digital noise grain and treating it the same way. Noise is worst in shadows, can carry color and is tied to the pixel grid. The cure for noise is more light; see noise reduction for cleaning it up afterward.
• Underexposing negative film to be safe. Thin shadows get brightened later and turn grainy. With negative film, a little too much light is far safer than too little.
• Judging grain from a scan at 100 percent. That is a much bigger enlargement than most prints, and the scan may add grain aliasing and sharpening of its own. Judge at the size people will see.
• Blaming the film for grain the development added. Long, hot or pushed development grows grain. Change one thing at a time to know which it was.
• Adding digital grain, then resizing or sharpening. Shrinking the file blurs the grain away, and sharpening after it turns it harsh. Grain goes on last.

Try this: see how grain depends on size

This takes about 10 minutes with any digital photo and any editor that has a grain control.

1. Pick a photo with a large smooth area, such as sky, a plain wall or an out-of-focus background.
2. Add grain until you can just see it when the whole photo fills your screen. Note the setting.
3. Export the photo twice: once at full size and once small, about 1,000 pixels on the long side, as you might for a phone or social post.
4. Look at both at full screen, then look at the full-size file at 100 percent.

How to judge it: the small export will look almost clean, the full screen view will show a gentle texture, and the 100 percent view will look rough. The grain did not change; the enlargement did. That is the same thing that happens when a negative is printed small or large. If you shoot film, do the film version: look at one negative as a small print or scan and as a big one, and find the size at which the grain first starts to draw your eye. That size is your working limit for that film, developer and format.

Film grain questions

Is film grain bad?

No. It is a trade-off and, for many photographers, a look they want. Grain only becomes a problem when it hides detail the picture needs or draws more attention than the subject.

Which films have the finest grain?

Slow films, usually rated around ISO 50 to 100, and films built with tabular crystals have the finest grain at any given speed. Slide films and modern color negative films are also very fine for their speed. Compare published RMS granularity figures if you want numbers, since they are measured the same way for every film.

What is T-grain or tabular grain?

It is an emulsion made of thin, flat silver halide crystals instead of chunky ones. The flat shape catches light across a wide face, so the film can be fast while its grain stays fine and its image stays sharp.

Why do my scans look grainier than my prints?

A scan viewed at 100 percent is often a much bigger enlargement than a print, and scanners can add grain aliasing and sharpening. Turn off scanner sharpening, view at the size you will use, and the gap usually shrinks.

Do digital cameras have grain?

Not in the film sense. The speckle in digital photos is noise from the sensor and the light itself. It rises with ISO much as grain rises with film speed, but it is shaped by the pixel grid and is worst in the shadows.

Why does grain move in old movies?

Each frame is a different piece of film with its own random crystals, so the grain pattern changes with every frame. Played at 24 frames per second, it seems to shimmer, which is a big part of the film look.

Film grain is one thread of film photography. Wherever you take it next, the size of the print and the light you give the film will shape it more than anything else.