Photography 101

Part 2: Focus and depthCheat sheet

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.

Part 2: Focus and depth

Cheat sheet

The formulas and starting settings from every chapter in Part 2: Focus and depth. Use the settings as a starting point, then check the photo.

Chapter 7Camera Lens

Formulas

Horizontal view
2 × arctan(sensor width ÷ (2 × focal length))
Full frame at 50 mm: about 40° horizontally
f-number
focal length ÷ effective opening diameter
50 mm at f/2: about 25 mm entrance pupil

Settings

Choose by need

Include more from one spot
Shorter focal length
Tighter frame from one spot
Longer focal length
Small close subject
Macro lens; check magnification and working distance
Everyday walk or travel
Standard view or flexible standard zoom
Distant bird or field sport
Telephoto; use a fast shutter for movement
Immersive curved-line view
Fisheye rather than rectilinear ultra-wide
Tall building, straight verticals
Keep camera level; shift a tilt-shift lens upward

Chapter 8Aperture and depth of field

Formulas

Opening diameter
focal length ÷ N
50 mm at f/4: a 12.5 mm opening
Background blur disk
grows with the opening
f/4 → f/2 makes the blur disk about 2× bigger
Looks sharp if
blur circle ≤ c = 0.03 mm
Full frame; smaller sensors use less
Near limit of sharpness
s(H − f) ÷ (H + s − 2f)
s = focus distance, H = hyperfocal distance
Far limit of sharpness
s(H − f) ÷ (H − s)
Infinity once s reaches H

Settings

More background blur, biggest first

Get closer, 2 m to 1 m
×2.7
Open up, f/4 to f/2
×2.0
Background 2 m to 20 m behind
×1.8
Zoom to 100 mm and step back
×1.3

Starting apertures

Portrait, soft background
f/2.8 or wider
Group photo
f/5.6 to f/8, focus on a middle row
Landscape
f/8 to f/11

Group at 4 m, 35 mm lens

f/2.8
sharp 3.1 to 5.5 m
f/5.6
sharp 2.6 to 8.8 m
f/8
sharp 2.3 to 17.9 m

Chapter 9Sensor size and crop factor

Formulas

Crop factor
43.3 mm ÷ sensor diagonal
43.3 mm is the full-frame (36 × 24 mm) diagonal
Equivalent focal length
focal length × crop
50 mm on APS-C frames like 75 mm
Equivalent aperture (blur)
N × crop
33 mm f/1.8 on APS-C ≈ 50 mm f/2.7 on full frame
Sharpness limit
c ≈ 0.03 mm ÷ crop
MFT: 0.015 mm
Brightness
same f-number, same shutter, same ISO → same brightness
f/1.8 is f/1.8 for exposure on any sensor

Settings

Crop factors

Full frame, 36 × 24 mm
1×
APS-C (Nikon, Sony, Fujifilm)
1.5×
APS-C (Canon)
1.6×
Micro Four Thirds
2×
1-inch
2.7×
Phone main camera
about 3.5×

Match a full-frame f/2.8 portrait

APS-C
about f/1.8
Micro Four Thirds
about f/1.4

A 50 mm lens frames like

APS-C (1.5×)
75 mm, a good portrait lens
Micro Four Thirds
100 mm

Chapter 10Hyperfocal distance

Formulas

Hyperfocal distance
H = f2 ÷ (N × c) + f
50 mm, f/8, c = 0.03 mm: 2500 ÷ 0.24 + 50 ≈ 10.5 m
Focus at H
sharp from H/2 to ∞
H = 10 m: sharp from 5 m to the horizon
Focus at infinity
near limit ≈ H
Loses the foreground from H/2 to H
Near limit, focused at s
(H − f) × s ÷ (H + s − 2f)
Put s = H and it's H/2
What moves H
1 stop down: ÷ 1.4  ·  2 stops: ÷ 2  ·  2× focal length: × 4
Because f is squared

Settings

Full frame, c = 0.03 mm

24 mm at f/8
2.42 m
24 mm at f/11
about 1.7 m
24 mm at f/16
1.22 m
50 mm at f/8
10.47 m
50 mm at f/16
5.26 m
70 mm at f/16
10.28 m

In the field

Not sure of the distance
Focus a little beyond H
Farthest thing is a treeline
Focus slightly closer than H
Foreground closer than H/2
Focus stack

Chapter 11Diffraction and the sharpest aperture

Formulas

Airy disk
≈ 2.44 × wavelength × N
Green light: about 1.34 µm per f-number
At f/16
1.34 µm × 16 ≈ 21.5 µm
Depends only on the f-number, not the lens or camera
Starts to show at 100%
Airy disk ≈ 2 pixels
No sharp cutoff; smaller pixels show it sooner
Across sensor sizes
same look at N × crop
MFT at f/8 looks like full frame at f/16

Settings

Airy disk size

f/4
5.4 µm
f/8
10.7 µm
f/11
14.8 µm
f/16
21.5 µm
f/22
29.5 µm

Landscapes, in order

Start
f/8 to f/11 at the hyperfocal distance
Foreground still soft
f/16, fine for screens and small prints
Very close foreground
Focus stack instead of f/22

Your lens's sharpest aperture

Test first
Wide open, 1 and 2 stops down
Good starting point
2 to 3 stops down