📚 Year 8 Media Formula & Theorem Quick Reference Handbook | 八年级媒体公式定理速查手册
Welcome to your go-to revision companion for Year 8 Cambridge Media Studies. This handbook collects the essential formulas, rules, and theoretical equations you need to analyse and create media texts with confidence. Each entry is presented as a memorable 'formula' or 'theorem' that captures a key concept in media language, representation, production, or audience theory.
欢迎使用这本八年级剑桥媒体研究速查手册。本手册汇集了你需要掌握的核心公式、规则和理论方程，帮助你自信地分析和创作媒体文本。每个条目都以易记的“公式”或“定理”形式呈现，浓缩了媒体语言、表征、制作或受众理论中的关键概念。
1. The Exposure Triangle | 曝光三角
Exposure = Aperture × Shutter Speed × ISO
In photography and cinematography, a correctly exposed image depends on balancing three variables. Aperture (f-number) controls the lens opening and depth of field; shutter speed determines motion blur; and ISO sets the sensor's light sensitivity. Halving shutter speed requires doubling ISO or opening the aperture by one stop to maintain equivalent exposure. This relationship is the foundation of manual camera control.
在摄影和电影制作中，正确曝光的画面取决于三个变量的平衡。光圈（f值）控制镜头开口和景深；快门速度决定运动模糊程度；ISO设定感光元件的感光度。将快门速度减半，就需要将ISO翻倍或将光圈开大一档，才能保持相同曝光。这一关系是手动控制相机的基础。
- Aperture scale (full stops): f/2.8, f/4, f/5.6, f/8, f/11, f/16
- 光圈级数（整档）: f/2.8, f/4, f/5.6, f/8, f/11, f/16
- Common shutter speeds (seconds): 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30
- 常见快门速度（秒）: 1/1000, 1/500, 1/250, 1/125, 1/60, 1/30
- ISO values (doubling sensitivity): 100, 200, 400, 800, 1600
- ISO值（感光度翻倍）: 100, 200, 400, 800, 1600
2. Rule of Thirds Grid Ratio | 三分法网格比例
Ideal subject placement = intersection of 1/3 horizontal and 1/3 vertical lines
The frame is divided into nine equal rectangles by two horizontal and two vertical lines. Placing key subjects along these lines or at their intersections creates a more dynamic and balanced composition than centring. The implied ratio of 1/3 to 2/3 guides the viewer's eye naturally through the image and can be applied to horizons, eyes in portraiture, and points of interest in landscapes.
画面被两条水平线和两条垂直线划分为九个相等的矩形。将关键主体放置在这些线上或它们的交叉点上，能比居中构图创造出更富动感、更平衡的画面。三分之二与三分之一的隐含比例能自然地引导观众的视线，适用于地平线、人像中的眼睛以及风景中的兴趣点。
- Horizon line: Place on the upper third for emphasis on foreground; lower third for sky.
- 地平线： 置于上方三分之一处以强调前景；置于下方三分之一处以突出天空。
- Portrait eyeline: Align eyes with the upper horizontal line.
- 人像视线： 将眼睛与上方水平线对齐。
3. Depth of Field Approximation | 景深近似公式
DoF ≈ (2 × CoC × f-number × subject distance²) / (focal length²)
Depth of field (DoF) is the distance between the nearest and farthest objects that appear acceptably sharp. The simplified formula shows that DoF increases with smaller apertures (larger f-number), shorter focal lengths, and greater camera–subject distances. CoC (circle of confusion) is a constant based on sensor size. For a smartphone sensor, CoC is roughly 0.005 mm; for an APS-C DSLR, about 0.02 mm. Understanding this relationship allows filmmakers to control background blur deliberately.
景深是指最近和最远的被摄体之间能清晰成像的距离范围。简化公式显示，景深随着光圈变小（f值增大）、焦距变短以及相机与被摄体距离增大而增加。CoC（模糊圈）是一个基于传感器尺寸的常数。对于智能手机传感器，CoC约为0.005毫米；对于APS-C单反相机，约为0.02毫米。理解这一关系有助于电影制作者有意识地控制背景虚化。
- Shallow DoF: large aperture (f/2.8), long focal length (85 mm), close subject. Effect: blurred background, isolates subject.
- 浅景深： 大光圈（f/2.8）、长焦距（85 mm）、近被摄体。效果：背景虚化，突出主体。
- Deep DoF: small aperture (f/16), wide lens (24 mm), distant subject. Effect: everything in focus, used in landscapes.
- 大景深： 小光圈（f/16）、广角镜头（24 mm）、远被摄体。效果：全景清晰，用于风景拍摄。
4. 180-Degree Rule | 180度规则
Camera must stay within the 180° semicircle on one side of the axis of action
When filming two characters in conversation, draw an imaginary line (the 'line of action') through them. All cameras should be positioned within the same 180° arc on one side of that line. Crossing the line reverses screen direction and disorients the viewer. This theorem maintains consistent spatial relationships and is a fundamental continuity editing principle in film and television.
在拍摄两位角色的对话场景时，在他们之间画一条假想的“动作轴线”。所有机位都应保持在这条线同一侧的180°半圆内。跨越这条线会颠倒屏幕方向，让观众迷失空间感。这个定理维持了空间关系的一致性，是电影电视中基本的连贯性剪辑原则。
- Example: If Character A is frame-left and Character B frame-right in the master shot, all coverage must preserve A-left, B-right.
- 示例： 如果主镜头中角色A在画面左侧、角色B在右侧，那么所有分镜头都必须保持A在左、B在右。
- Controlled crossing: You may reset the line by showing a camera move or a cutaway of a neutral object (e.g., a clock).
- 有控制的越轴： 可以通过展示摄影机移动或插入中性物体（如一个时钟）的空镜头来重置轴线。
5. Three-Point Lighting Ratio | 三点布光比例
Key light : Fill light : Back light = 2 : 1 : 0.5 (typical drama ratio)
Three-point lighting uses a key light (primary source, creating shadows), a fill light (softens shadows, placed opposite the key), and a back light (separates subject from background). The ratio between key and fill determines contrast and mood. A high ratio (4:1) creates dramatic, low-key lighting; a low ratio (1.5:1) yields flat, high-key lighting common in sitcoms. The back light is often set around half the key’s intensity to add depth without overexposure.
三点布光使用主光（主要光源，制造阴影）、辅光（柔化阴影，置于主光对侧）和轮廓光（将主体与背景分离）。主光与辅光的比例决定了对比度和氛围。高比例（4:1）营造戏剧性的低调光；低比例（1.5:1）产生平淡的高调光，常见于情景喜剧。轮廓光通常设为主光强度的一半左右，以增加深度感而不致过曝。
- Low-key lighting (film noir, thriller): Key:Fill = 4:1 or higher. Deep shadows, high contrast.
- 低调光（黑色电影、惊悚片）： 主辅比4:1或更高。阴影浓重，高对比度。
- High-key lighting (comedy, news): Key:Fill = 1:1 to 2:1. Minimal shadows, even illumination.
- 高调光（喜剧、新闻）： 主辅比1:1至2:1。极少阴影，光照均匀。
6. Colour Harmony: Complementary Contrast | 色彩和谐：互补对比
Colour A + Complementary Colour B → Neutral grey / white light (additive mixing)
On the RGB colour wheel, complementary pairs are directly opposite: Red–Cyan, Green–Magenta, Blue–Yellow. In additive colour theory (used for screens), mixing two complementary colours of equal intensity produces white light. In film colour grading, the popular 'teal and orange' look uses complementary contrast to make skin tones (orange) stand out against cyan backgrounds. This theorem underpins colour scripts and visual storytelling.
在RGB色轮上，互补色两两相对：红与青、绿与品红、蓝与黄。在加色理论（用于屏幕）中，将两种等强度的互补色混合会产生白光。在电影调色中，流行的“青橙色调”利用互补对比，使肤色（橙色）在青色背景上脱颖而出。这个定理是色彩剧本和视觉叙事的基础。
- Teal & Orange application: Push shadows towards cyan, midtones/highlights towards orange. Creates depth and separation.
- 青橙色调应用： 将阴影推向青色，中间调/高光推向橙色。营造深度感和分离感。
- Triadic harmony: Three colours equally spaced (e.g., Red, Green, Blue). Used for vibrant, balanced palettes.
- 三色和谐： 三种等距分布的颜色（如红、绿、蓝）。用于充满活力且平衡的调色板。
7. Sound Pressure Level (dB) Formula | 声压级公式
SPL (dB) = 20 × log₁₀(P / Pref)
Sound pressure level is measured in decibels (dB), a logarithmic unit that matches human hearing perception. The reference pressure Pref is 20 micropascals (µPa), the threshold of human hearing. A whisper at 1 metre registers about 20–30 dB; normal conversation is 60 dB; a rock concert can reach 110 dB. In media production, understanding dB helps in setting dialogue levels and avoiding distortion. A change of +6 dB represents roughly a doubling of sound pressure.
声压级以分贝（dB）为单位，这一对数单位与人耳的听觉感知特性相匹配。参考声压 Pref 为20微帕（µPa），即人类听觉的阈值。一米远处的耳语声约为20–30 dB；正常交谈为60 dB；摇滚音乐会可达110 dB。在媒体制作中，理解分贝有助于设定对话电平并避免失真。增加6 dB大致表示声压加倍。
- Safe recording levels: Dialogue should average around -12 dBFS in digital systems, with peaks no higher than -6 dBFS.
- 安全录制电平： 数字系统中，对白平均电平应在-12 dBFS左右，峰值不超过-6 dBFS。
- Doubling perceived loudness: Requires approximately +10 dB increase.
- 响度感加倍： 大约需要增加10 dB。
8. Narrative Structure Theorem (Todorov) | 叙述结构定理（托多罗夫）
Story = Equilibrium → Disruption → Recognition → Repair → New Equilibrium
Tzvetan Todorov's narrative theory proposes that most stories follow a five-stage pattern. The initial state of balance (equilibrium) is broken by an event (disruption), the characters recognise the disruption, attempt to repair the damage, and eventually reach a new equilibrium—often changed. This formula helps deconstruct mainstream film narratives and is visible in everything from fairy tales to blockbuster superhero movies.
茨维坦·托多罗夫的叙事理论提出，大多数故事遵循五阶段模式。初始的平衡状态（均衡）被某一事件（破坏）打破，角色意识到破坏，尝试修复损害，最终达到一个新的均衡——通常已发生改变。这个公式有助于解构主流的电影叙事，从童话故事到超级英雄大片中都能看到它的踪影。
- Example (The Lion King): Equilibrium: Pride Lands peaceful. Disruption: Scar's betrayal, Mufasa's death. Recognition: Simba learns truth. Repair: Simba returns and fights Scar. New Equilibrium: Simba becomes king, circle of life restored.
- 示例（《狮子王》）： 均衡：荣耀大地和平。破坏：刀疤背叛，木法沙死去。识别：辛巴得知真相。修复：辛巴回归并挑战刀疤。新均衡：辛巴成为国王，生命之环恢复。
9. Semiotic Equation: The Sign | 符号学方程：符号
Sign = Signifier + Signified
According to Ferdinand de Saussure, a sign consists of two parts: the signifier (the physical form—written word, image, sound) and the signified (the mental concept it evokes). Their relationship is arbitrary and based on social convention. A red traffic light (signifier) signifies 'stop' (signified). In media analysis, this equation helps decode how meaning is constructed through visual and auditory codes. Recognising that signs are cultural constructs enables critical reading of advertisements, news, and films.
根据费尔迪南·德·索绪尔的理论，符号由两部分组成：能指（物理形式——书面文字、图像、声音）和所指（它唤起的心理概念）。它们之间的关系是任意的，基于社会约定。红色交通灯（能指）表示“停止”（所指）。在媒体分析中，这一方程有助于解码意义如何通过视觉和听觉代码构建。认识到符号是文化建构的产物，就能对广告、新闻和电影进行批判性阅读。
- Iconic sign: Signifier resembles signified (e.g., a photograph).
- 图像符号： 能指与所指相似（如照片）。
- Indexical sign: Signifier is directly connected to signified (e.g., smoke indicates fire).
- 指示符号： 能指与所指有直接关联（如烟指示火）。
- Symbolic sign: Arbitrary relationship, learnt through culture (e.g., the word 'tree').
- 象征符号： 任意关系，通过文化学习获得（如“树”这个词）。
10. Montage Theory: 1+1=3 | 蒙太奇理论：一加一等于三
A + Shot B = New Concept C (emotional/narrative meaning not present in either shot alone)
Sergei Eisenstein's theory of montage emphasises that the collision of two images creates a third meaning that exists only in the viewer's mind. Placing a shot of a politician beside a shot of a peacock might generate 'vanity'. A classic example: a neutral face followed by a bowl of soup suggests hunger; the same face followed by a coffin suggests grief. This formula is the essence of editing as a creative, meaning-generating process, not just a joining of scenes.
谢尔盖·爱森斯坦的蒙太奇理论强调，两个图像的碰撞会产生第三种意义，这一意义仅存在于观众心中。将一个政客的镜头与一只孔雀的镜头并置，可能产生“虚荣”。一个经典例子：一个面无表情的脸接一碗汤的画面，暗示饥饿；同一张脸接一副棺材，则暗示悲伤。这个公式体现了剪辑作为一种创造性的、产生意义的过程的本质，而不仅仅是场景的拼接。
- Metric montage: Cutting according to a precise number of frames, creating rhythm through length.
- 度量蒙太奇： 根据精确的帧数进行剪辑，通过长度创造节奏。
- Rhythmic montage: Cutting based on visual content and movement within the frame.
- 节奏蒙太奇： 基于画面内部的视觉内容和运动进行剪辑。
- Tonal/Overtonal montage: Cutting to express emotional atmosphere and thematic resonance.
- 调性/泛音蒙太奇： 通过剪辑表达情感氛围和主题共鸣。
Published by TutorHao | Media Revision Series | aleveler.com
更多咨询请联系16621398022（同微信）
或截图后用「扫一扫 → 相册」选择本图