Photography 101

Part 1: ExposureChapter 4

Tools

Contents

Part 1: Exposure

  1. 1 Mastering the Exposure TriangleBalance aperture, shutter speed and ISO for brightness, depth, motion and noise.
  2. 2 ISO and image noiseWhen to raise ISO, why grain appears, and how to trade it for a faster shutter.
  3. 3 MeteringWhat the meter aims for, how to read it, the four metering modes, and Sunny 16 when there's no meter.
  4. 4 Shooting modes and the histogramLet the camera set one setting, steer it with exposure compensation, and check the result with the histogram and zebras.
  5. 5 Dynamic rangeHow many stops a camera can hold at once, what to keep when a scene is wider, and measured figures for real cameras.
  6. 6 Shutter speed and motionCamera shake, freezing or blurring a moving subject, and ND filters for long exposures.
  7. Part 1 cheat sheetFormulas and starting settings from chapters 1–6.
  8. Part 1 quizCheck yourself on chapters 1–6.

Part 2: Focus and depth

  1. 7 Camera LensLens anatomy and how to choose wide, standard, telephoto, prime, zoom and specialist lenses for real subjects.
  2. 8 Aperture and depth of fieldWhy a wider aperture blurs the background, what else controls blur, and the shape of bokeh.
  3. 9 Sensor size and crop factorWhat a smaller sensor crops, equivalent focal length and aperture, and why phones fake the blur.
  4. 10 Hyperfocal distanceSharp from here to infinity: focusing landscapes with blur circles, focus stacking and a cheat card.
  5. 11 Diffraction and the sharpest apertureWhy f/22 looks soft, where your lens is sharpest, and how pixel size changes it.
  6. Part 2 cheat sheetFormulas and starting settings from chapters 7–11.
  7. Part 2 quizCheck yourself on chapters 7–11.

Part 3: Composition

  1. 12 The composition reading planAll 15 chapters of The Elements of Composition, with printed page numbers and a photography lesson for each.
  2. 13 Introduction to compositionComposition as visual communication: choose what to show, compare three frames, and see how viewers read them.
  3. 14 What is composition?Arrange subject, space and edges to change what a photograph says; compare photos and make three versions of one scene.
  4. 15 Focal pointsChoose where the eye lands first, use contrast and space to build a visual path, then test thirds and diagonals in a field exercise.
  5. 16 LinesFollow straight, curved and implied lines through a photograph, then make three frames of one subject from different positions.
  6. 17 ShapesFind shapes made by subjects and space, use a frame within the frame, and compare three ways to place one subject.
  7. 18 TexturesMake a surface feel tangible with light, detail and context, then photograph one material three ways.
  8. 19 PatternsUse repetition to build rhythm, break a pattern to draw attention, and make three versions of one repeated scene.
  9. 20 SpaceUse positive and negative space, fill the frame, and simplify without losing meaning.
  10. 21 DepthLayer foreground, middle ground and background, and use perspective or deep space to show distance.
  11. 22 BalanceWeigh elements with symmetry, asymmetry and radial arrangements; explore the golden ratio as an optional guide.
  12. 23 ContrastCreate meaning and focus through contrasting subjects, light, shadows and colour.
  13. 24 ColorChoose hue, saturation and brightness, then compare complementary, triadic, analogous and monochromatic palettes.
  14. 25 ToneRead shadow, midtone and highlight; shape global and local tone while keeping meaningful detail.
  15. 26 AngleChange camera height and tilt to compare level, straight up or down, high and low viewpoints.
  16. 27 Composition conclusionBring the elements together in a four-frame story and develop your own way of seeing.

Part 4: Color Theory

  1. 28 Color Theory in PhotographyUse HSL, warm and cool depth, four color harmonies, white balance and selective editing to guide attention.
  2. 29 White balanceRead the color of light, match Kelvin and tint, and choose what to preserve when lights mix.

Tools

  1. Color wheelExplore hues, adjust saturation and luminosity, enter RGB or hex values, and preview the color live.
  2. Photo editorTry light, colour, detail and crop adjustments on a sample or your own photo, then save the result.
  3. Golden hour plannerSunrise, sunset, golden hour and blue hour for where you are, and where the sun rises and sets.
  4. ND filter calculatorYour shutter speed with an ND filter on, and a countdown timer for bulb mode.
  5. Depth of field calculatorHow much is sharp for your lens, aperture and focus distance, and the hyperfocal distance.
  6. Photo info and location removerSee a photo's camera settings and where it was taken, then remove the location before you share it.

Chapter 4Part 1: Exposure

Shooting modes
and the histogram

Let the camera set one of the three settings for you, steer it with exposure compensation, and check the result with the histogram before you move on.

Mf/41/250ISO100
Highlights
Shadows

Bottom right of the viewfinder: the live histogram. Striped areas are zebras, parts of the picture pushed to pure white.

0 stops

f/4
Auto
1/250
Auto
100
Auto

Shooting modes

In manual you set all three. In the other modes you pick the setting that matters for the photo, and the camera sets the rest to hit the meter's target. Brands use different letters for the same modes.

ModeOn the dialYou setThe camera setsUse it when
ManualMAperture, shutter, ISONothingLight is steady, or the meter gets fooled (snow, stage, night sky)
Aperture priorityA (Nikon, Sony, Fujifilm), Av (Canon, Pentax)Aperture, ISOShutter speedDepth of field matters: portraits, landscapes
Shutter priorityS (Nikon, Sony, Fujifilm), Tv (Canon, Pentax)Shutter, ISOApertureMotion matters: sports, birds, panning
Manual with Auto ISOM with ISO set to AutoAperture, shutterISOBoth matter and the light keeps changing: events, wildlife
ProgramPISOAperture and shutterQuick snaps

Try it in the lab

  1. Switch to A / Av. The shutter slider now says Auto.
  2. Open the aperture to f/2. The camera speeds the shutter up by two stops, to 1/1000 s. The meter stays at 0.
  3. Set ISO 200, then open to f/1. The camera needs 1/8000 s but stops at 1/4000 s. The shutter value blinks and the picture is a stop too bright.

When the camera runs out

A priority mode can only move its setting as far as the camera allows. When it hits the end, most cameras blink that value in the viewfinder. Change your own setting, the ISO, or add an ND filter.

Changing the metering mode

A different metering mode changes the meter's suggestion. In A, S or P the camera follows it, so the setting the camera controls changes. In M with Auto ISO, the ISO changes. In M with a fixed ISO, only the needle moves; the photo stays as you set it.

Exposure compensation

The meter often treats what it sees as a middle tone. That can turn snow grey or make a dark stage too bright. Use exposure compensation (+/−) to correct its guess: + makes the photo brighter; − makes it darker. It works when the camera chooses a setting: in A / Av, S / Tv and P, or often in M with Auto ISO. In M with a fixed ISO, you choose aperture, shutter and ISO, so +/− only moves the meter's guide. The photo stays the same.

Try it in the lab

  1. In A / Av, drag compensation to +1. The camera slows the shutter by one stop, and the histogram slides right.
  2. Keep going to +2. Zebras cover the sky and the histogram hits the right wall.
  3. Pull it back until the zebras almost disappear. That is the brightest exposure that keeps the sky.

Rules of thumb

Snow, beach, white wedding dress
+1 to +2
Backlit person, sun behind them
+1 to +2
Bright sky taking up half the frame
+⅔ to +1
Dark background, spotlit subject
−1 to −2
Sunset, to keep the colour rich
−⅔ to −1

Reading the histogram

A histogram is a bar chart of brightness. Black is on the left, white on the right, and the height shows how much of the picture has that brightness. It is the same whatever the screen brightness or the room you're in, so trust it over how the photo looks on the back of the camera.

Too darkPiled up on the left, empty on the right. Shadows turn to mud and noise.
This scene: balancedIts important tones fit within the range. Other scenes can look different.
Clipped previewA spike against the right wall shows white areas with no detail in this preview.

There is no perfect shape

The shape follows the scene. A snowy field should sit to the right and a night street to the left. Check the walls for clipping, then decide whether the clipped areas matter to your photo. A brightness histogram can also miss a clipped colour channel; use an RGB histogram if your camera offers one. See Nikon's histogram guide.

Zebras and blinkies

Many cameras can mark the clipped parts for you: zebras (moving stripes in the live view) or blinkies (flashing areas in playback). A clipped sun or street lamp is normal. A clipped face, cloud or white dress is worth fixing.

If you shoot RAW, treat camera warnings as guides to the preview: RAW editing can sometimes recover detail that appears clipped there. Nikon's RAW editing manual shows this difference.

How the histogram is plotted

The camera builds the histogram from the preview picture, pixel by pixel. Below, a photo is shrunk to 1,440 big pixels so you can see every one of them counted. Tap a bar to light up the pixels in it.

Dashed lines: where 1, 2, 3… stops below white land. Tap a bar, or slide along the bars; tap it again to clear.

Histogram

1/3 stop per step, applied to the light before it's encoded, as in the camera.

Three steps

  1. Find each pixel's brightness. A pixel has red, green and blue values from 0 to 255. The brightness histogram mixes them roughly the way your eye does, with green counting most:

    Y = 0.2126 R + 0.7152 G + 0.0722 B

  2. Drop it into a bin. With 256 bins, a pixel of brightness 118 adds one to bin 118. Fewer bins group neighbouring values; this lab uses 32 bins of 8 values:

    bin = ⌊ Y × bins ÷ 256 ⌋

  3. Draw one bar per bin. Its height is how many pixels landed there, scaled so the tallest bar fits. So heights show proportions, not a number of pixels, and all the bars together add up to every pixel in the picture.

Brightness or RGB?

An RGB histogram does the same count three times, once each for red, green and blue. It can show a clipped colour the brightness histogram hides: a bright red flower can push red to 255 while its brightness, with red counting only 21%, is around 60 to 80, nowhere near the right wall.

What it's counted from

The camera counts the JPEG preview, after its picture style and white balance, not the RAW file. That's why changing the picture style can change the histogram, and why a RAW file can sometimes hold a little more highlight detail than the histogram shows.

Where the stops fall

Each stop down halves the light, but the 0–255 values aren't light: they're encoded with a curve (the sRGB gamma, about light1/2.2) that spreads the dark tones out. So the stops sit unevenly across the histogram, getting narrower towards the shadows.

Stops below whiteLightValue (0–255)Width of that stop
0 (white)100%255
−150%18867 values
−225%13751 values
−2½ (middle grey)18%118
−312.5%9938 values
−46.25%7128 values
−53.1%4922 values

What that means when you change exposure

One stop brighter doesn't slide the histogram a fixed distance. Middle grey moves from 118 to 162, but a tone at 188 moves all the way to 255, and anything brighter piles up against the right wall as pure white. Try it with the exposure slider above.

Middle grey at 118 sits a little left of centre, which is why a well-exposed everyday scene often has its bulk just left of the middle. Camera JPEGs add their own contrast curve on top of sRGB, so real positions shift a little from these numbers.