Photography: camera, light and composition

In short

Photography is the craft of recording an image by controlling how much light reaches a sensor or film, how sharp and how deep the recorded zone is, and how the elements are arranged inside the frame. The whole subject reduces to three linked systems: the camera (sensor, lens, aperture, shutter, ISO), the light (quantity, quality, direction, colour), and the composition (framing, balance, perspective, visual flow). In a B.Sc Visual Communication course it is examined through theory papers on camera mechanics and exposure, practical records, and a portfolio viva. It is tested in placement rounds at Indian studios, ad agencies, OTT and news organisations (Times Internet, Network18, The Hindu, Ogilvy, Dentsu, Nykaa, Myntra, Flipkart studios, wedding and architecture studios), where interviewers ask for exposure reasoning and lighting diagrams, not only for photographs.

Explained

The camera: body, sensor and lens

• Camera obscura to digital: light passing through a small opening forms an inverted image; a lens replaces the pinhole to gather more light and focus it on film or a sensor.
• Image sensor types: CCD (older, low noise, costly) and CMOS (current standard, on-chip readout, cheaper, fast, used in nearly all DSLRs, mirrorless cameras and phones). Each photosite converts photons into charge; a Bayer colour filter array (R, G, B in a 2:1 green-weighted pattern) plus demosaicing gives colour.
• Sensor formats and crop factor: Medium format (larger than 36×24 mm) · Full frame 36 × 24 mm (crop 1.0) · APS-C 23.6 × 15.7 mm (crop 1.5; Canon APS-C 22.3 × 14.9 mm, crop 1.6) · Micro Four Thirds 17.3 × 13 mm (crop 2.0) · 1-inch type (crop 2.7) · phone sensors (crop 5-7).
• Camera classes: DSLR (reflex mirror + optical viewfinder, phase-detect AF module), mirrorless (no mirror, electronic viewfinder, on-sensor hybrid AF - now the industry default), bridge/compact, large-format and view cameras (movements for perspective control), medium-format digital, smartphone computational cameras, action and 360 cameras.
• Lens anatomy: elements and groups, aperture diaphragm (iris blades), focus and zoom mechanism, coatings to cut flare, image stabilisation (optical IS/VR, or in-body IBIS).
• Shutter types: focal-plane mechanical shutter (two curtains; flash sync limited to the X-sync speed, usually 1/200-1/250 s), leaf/central shutter (in-lens, syncs at all speeds), electronic shutter (silent, but rolling-shutter skew on fast motion and banding under LED/fluorescent light).
• Viewfinder and focus aids: optical vs electronic viewfinder, focus peaking, magnified live view, back-button focus; AF modes - single (AF-S/One Shot) for still subjects, continuous (AF-C/AI Servo) for moving subjects, eye/animal detection AF.
• File formats: RAW keeps the unprocessed sensor data (12-14 bit, full editing latitude for exposure and white balance), JPEG is 8-bit, compressed and baked in; TIFF/PSD for lossless editing output; DNG as an archival RAW.

Exposure: aperture, shutter speed and ISO

• Exposure = illuminance on the sensor × time. The three controls form the exposure triangle; one stop means a factor of 2 in light, and the same change can be made by any of the three.
• Aperture (f-number) N = f / D, where f is focal length and D the effective diameter of the entrance pupil. Standard full stops: f/1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22 - each step halves the light because area scales as 1/N². A smaller f-number is a larger opening.
• Shutter speed full stops: 1 s, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000 s. It fixes motion blur: freeze sport at 1/1000 s; blur water at 1/4 s or slower on a tripod.
• ISO (ISO 12232 sensitivity) amplifies the signal: 100, 200, 400, 800, 1600... Each doubling gains a stop but lowers signal-to-noise ratio, so shadow noise and loss of fine detail increase. Base ISO (usually 64-200) gives maximum dynamic range.
• Equivalent exposures: f/8 at 1/125 s, ISO 200 ≡ f/5.6 at 1/250 s, ISO 200 ≡ f/8 at 1/250 s, ISO 400. Same brightness, different depth of field, motion and noise - this trade-off is the examiner's favourite question.
• Exposure modes: M (manual), Av/A (aperture priority - you set aperture, camera sets shutter), Tv/S (shutter priority), P (program), Auto/Scene, B (bulb) for long exposures. Auto ISO with a minimum shutter speed is the practical hybrid.
• Metering modes: evaluative/matrix (whole frame, scene-aware), centre-weighted, partial, spot (1-3% of frame - used for stage, backlight, dark-skin-tone exposure). All reflected-light meters assume a mid-grey of about 18% reflectance, so a snow field reads under-exposed and a black background over-exposed; correct with exposure compensation (+/- EV).
• Incident vs reflected metering: a handheld incident meter with a dome measures the light falling on the subject and ignores subject tone - the studio standard; the camera meter measures reflected light.
• Histogram: graph of pixel count against brightness (left = shadows, right = highlights). Clipping at either end loses data permanently in that channel; "expose to the right" without clipping maximises signal-to-noise in RAW. Zebras and blinkies warn of clipping while shooting.
• Dynamic range is the ratio between the brightest and darkest recordable detail, in stops (about 11-15 stops on current sensors against roughly 20+ for the eye); handle extremes with graduated filters, fill flash, or HDR/bracketing.
• Reciprocity: exposure depends on the product of intensity and time - valid for digital; film shows reciprocity failure at very long exposures.
• Zone System (Ansel Adams): 11 zones, 0 (pure black) to X (pure white), Zone V = mid-grey; meter the key tone and place it in a chosen zone. Still examined in film and B&W papers.

Focal length, depth of field and perspective

• Focal length sets angle of view. On full frame: ultra-wide 14-24 mm, wide 24-35 mm, normal ~50 mm (close to the diagonal of 43 mm, perspective similar to human viewing), short telephoto 85-135 mm (portraits), telephoto 200 mm and up (sport, wildlife), macro (1:1 reproduction), fisheye, tilt-shift.
• Equivalent focal length = actual × crop factor. A 50 mm lens on APS-C (1.5×) frames like 75 mm. Crop factor changes framing, not the aperture's light-gathering per unit area.
• Perspective is set by camera-to-subject distance, not by the lens. Wide lenses are used close, so near objects loom (useful in interiors, harsh on faces); telephotos are used far, so planes compress and backgrounds appear larger and closer.
• Depth of field (DoF) is the zone of acceptable sharpness around the plane of focus. It decreases with wider aperture, longer focal length and closer subject; roughly one-third in front, two-thirds behind the focus plane at ordinary distances (the split is near-equal in macro).
• Circle of confusion (CoC): the largest blur circle still read as a point - conventionally about 0.03 mm for full frame, 0.02 mm for APS-C, with a 0.25 mm print-viewing criterion behind it.
• Hyperfocal distance: focus there and everything from half that distance to infinity is acceptably sharp - the landscape technique.
• Bokeh: the character of out-of-focus areas, shaped by the number and curvature of aperture blades, aberration and apodisation; not the same as "a lot of blur".
• Diffraction softens the whole image at very small apertures (typically beyond f/11 on APS-C, f/16 on full frame); most lenses are sharpest about two stops from wide open - the sweet spot.
• Aberrations and defects: spherical and chromatic aberration, coma, barrel/pincushion distortion, vignetting, flare and ghosting, field curvature; corrected in design, by stopping down, by lens hoods and by software profiles.

Light: quantity, quality, direction, colour

• Sources: natural (sun, sky, clouds, reflected light; golden hour, blue hour, overcast as a giant softbox) and artificial (speedlight/flash, studio strobe with modelling lamp, continuous LED panels, tungsten, HMI, fluorescent).
• Quality - hard vs soft: governed by the apparent size of the source relative to the subject. A bare bulb or midday sun is small and distant - hard light, sharp-edged shadows. Move the same source closer, or spread it through a softbox, umbrella, scrim or bounce - large relative size, soft light, gradual shadow edge.
• Direction: front (flat, hides texture), 45° (Rembrandt), side/split (maximum texture and form), top, backlight/contre-jour (rim, silhouette), underlight (unnatural, used for horror), butterfly/Paramount (on-axis above, beauty work).
• Classical lighting setups: key light (main, sets exposure and shadows), fill (lifts shadows, sets contrast), back/rim/hair light (separation from background), background light, kicker; add a reflector, flag, gobo, cutter, snoot, barn doors, grid, gel.
• Lighting ratio = key+fill : fill, measured in stops. 2:1 is low contrast (corporate portraits), 4:1 standard, 8:1 dramatic/low key. High key = bright, low contrast; low key = dark, dominated by shadow.
• Inverse square law: illuminance falls as 1/d² from a point source - so a near light falls off fast (good for isolating a subject), a distant light gives even coverage.
• Colour temperature (kelvin): candle ~1,900 K, tungsten bulb 2,800-3,200 K, early LED panels 3,200/5,600 K switchable, noon daylight 5,200-5,600 K, electronic flash ~5,500 K, overcast 6,500-7,500 K, open shade/blue sky 8,000-10,000 K+. Lower K looks warmer in appearance even though it is physically cooler.
• White balance instructs the camera which illuminant to treat as neutral: presets (daylight, cloudy, shade, tungsten, fluorescent, flash), Kelvin entry, custom WB off a grey card, auto WB. On a RAW file WB is a metadata instruction and can be reset losslessly; on a JPEG it is baked in. CRI/TLCI rate how faithfully an LED renders colour (CRI 95+ for product and portrait work).
• Flash control: guide number (GN) rates power; TTL metering fires a pre-flash and computes power automatically, manual sets fractions (1/1, 1/2, 1/4...). Sync speed caps ambient control; high-speed sync (HSS) pulses the flash to beat it; 1st vs 2nd curtain sync places the blur before or after the frozen image. Shutter speed controls the ambient exposure, aperture and ISO control the flash exposure - the core of flash-ambient balancing.
• Filters: UV/protector, circular polariser (cuts reflections and glare, deepens skies, costs 1-2 stops), ND (neutral density for long exposure or wide aperture in daylight), graduated ND, colour conversion/correction gels (CTO, CTB), diffusion.

Composition and visual language

• Rule of thirds: place horizons and subjects on the lines or intersections of a 3 × 3 grid; the golden ratio/phi grid and golden spiral are the stricter classical versions.
• Leading lines and diagonals direct the eye; curves (S-curve) create flow; horizontals calm, verticals assert, diagonals energise.
• Framing with arches, windows and foliage adds depth and isolates the subject; negative space gives a subject room and conveys scale or solitude.
• Balance: symmetry and reflections for formality; asymmetric balance of a small bright subject against a large dark mass for tension.
• Depth cues in a 2-D image: overlap, relative size, linear perspective and vanishing points, aerial haze, foreground-middleground-background layering, and selective focus.
• Point of view and angle: eye level (neutral), low angle (dominance, height), high angle/bird's-eye (context, diminishment), Dutch tilt (unease).
• Shot sizes: extreme long shot, long shot, mid shot, close-up, extreme close-up - carried over from film grammar and used in photo-essays.
• Pattern, repetition, rhythm and a break in pattern as the subject; texture revealed by raking side light; scale established by a human figure.
• Rule of odds, simplification, decluttering the edges, filling the frame, the "decisive moment" (Henri Cartier-Bresson); headroom, nose room/looking room, and leaving space in the direction of motion.
• Colour in composition: complementary and analogous harmonies, warm advance/cool recede, a single saturated accent in a muted field, monochrome and tonal contrast.
• Aspect ratio and orientation: 3:2 (35 mm), 4:3 (MFT, phones), 1:1 (Instagram feed), 16:9 (video), 4:5 and 9:16 (vertical social); crop intentionally at capture, keeping space for reframing.
• When to break the rules: dead-centre placement for a symmetric or confrontational portrait, a horizon on the centre line for a mirror reflection - a deliberate break is examined as a reasoned choice.

Workflow, standards and Indian legal practice

• Capture to delivery: shoot RAW → ingest and back up (two copies, one off-site) → cull → develop (Lightroom/Camera Raw, Capture One, DxO, darktable) → retouch (Photoshop, Affinity) → colour manage → export.
• Colour management: working spaces sRGB (web and most Indian print houses' default for quick jobs), Adobe RGB (wider, press work), ProPhoto RGB (editing only); monitor profiling with a colorimeter; ICC profiles and soft-proofing; CMYK conversion only at the press stage.
• Resolution for output: about 300 ppi for offset print, 150-200 ppi for large-format standing-distance prints, 72-144 ppi for screen. Print size (inch) = pixels ÷ ppi.
• Metadata and standards: EXIF (camera, exposure, GPS), IPTC Photo Metadata (creator, caption, credit, usage terms), XMP sidecars; keep creator and copyright fields filled - it is the cheapest proof of authorship.
• Copyright: a photograph is an "artistic work" under the Copyright Act, 1957; the photographer is the author and first owner, except where the photograph is taken under a contract of service or for valuable consideration at another's instance, when the commissioning party owns it unless the contract says otherwise - so always put ownership and licence in writing. Term: the Copyright (Amendment) Act, 2012 omitted section 25 (which gave photographs 60 years from publication), so a photograph now runs under section 22 - the author's lifetime plus 60 years from the year following death. Registration with the Copyright Office is voluntary, not a precondition to protection. Moral rights (paternity and integrity) stay with the author.
• Privacy, publicity and consent: get a model release for commercial use and a property release for private premises; personality rights have been protected by Indian courts in several recent injunctions. Photographing people in public for editorial use is generally permissible, but publishing in an advertisement without consent invites action.
• Restrictions in practice: defence establishments, many airports, ports, metro interiors, courts and some places of worship restrict photography; protected monuments - ASI generally allows still photography free at most sites, with fees or written permission for tripods, commercial shoots and a few notified monuments; drone work is governed by the Drone Rules, 2021 with the Digital Sky platform, UIN/remote-pilot certificate and the airspace zone map (green/yellow/red), and rules are amended often, so verify the current requirement before a shoot.
• Data protection: the Digital Personal Data Protection Act, 2023 is enacted, but under the DPDP Rules, 2025 the Data Fiduciary duties (notice, consent, breach intimation, erasure) take effect only from 13 May 2027; until then the IT Act section 43A and the SPDI Rules govern sensitive personal data held by a studio.
• Commerce: photography services attract GST at 18%; GST slabs since 22 September 2025 are 5%, 18% and 40%. Equipment import duty and warranty differ between Indian-warranty and grey-market bodies - an exam-irrelevant but interview-relevant point.

Key points

• Exposure triangle - aperture, shutter speed and ISO; a one-stop change in any one equals a doubling or halving of exposure.
• f-number N = f/D - area, and so light, scales as 1/N²; f/2 passes four times the light of f/4.
• Depth of field - shallower with a wider aperture, longer focal length or closer subject; deeper with the opposite.
• Crop factor - equivalent focal length = actual focal length × crop factor (APS-C 1.5-1.6, MFT 2.0).
• Perspective - set only by camera-to-subject distance; focal length merely changes how much is included.
• Hyperfocal distance - focus point that makes everything from half that distance to infinity acceptably sharp.
• Diffraction - resolution loss at very small apertures; the sharpest aperture is about two stops from wide open.
• Hard vs soft light - decided by the source's size relative to the subject, not by its wattage.
• Inverse square law - illuminance falls as 1/d²; moving a light twice as far gives a quarter of the light (two stops).
• Lighting ratio - (key + fill) : fill, expressed in stops; 2:1 low contrast, 8:1 dramatic low key.
• Three-point lighting - key sets the exposure and shadow, fill controls contrast, back light separates subject from background.
• Colour temperature - low kelvin = warm (tungsten ~3,200 K), high kelvin = cool (shade 8,000 K+); flash and daylight ~5,500 K.
• White balance - resettable losslessly in RAW, baked into JPEG; custom WB off a grey card is the reliable method.
• Metering - reflected meters assume 18% grey, so bright and dark scenes need exposure compensation; incident metering ignores subject tone.
• Histogram - the only objective exposure check on location; clipped ends mean unrecoverable data.
• Sync speed - the fastest shutter speed that fully exposes the frame with flash (about 1/200-1/250 s); HSS exceeds it at a power cost.
• Shutter controls ambient, aperture and ISO control flash - the rule for mixing strobe with daylight.
• Composition essentials - rule of thirds, leading lines, framing, negative space, layering for depth, and a reasoned break of the rule.
• Copyright Act, 1957 - the photographer is the first owner, except for commissioned work for valuable consideration; term is the author's lifetime plus 60 years (the old 60-years-from-publication rule in section 25 was omitted in 2012); registration voluntary.

Formulas and examples

Example 1 - Equivalent exposure. A correct reading is f/8 at 1/125 s, ISO 200. The client wants a blurred background, so you open to f/2.8. What shutter speed keeps the same exposure?

• Stops from f/8 to f/2.8: f/8 → f/5.6 → f/4 → f/2.8 = 3 stops more light.
• Compensate with 3 stops less time: 1/125 → 1/250 → 1/500 → 1/1000 s.
• Check with N²/t: 8²/(1/125) = 64 × 125 = 8,000; 2.8²/(1/1000) = 7.84 × 1000 = 7,840 ≈ 8,000 (f-numbers are rounded; f/2.83 would be exact). Answer: f/2.8 at 1/1000 s, ISO 200.

Example 2 - Inverse square law and lighting ratio. A softbox at 2 m gives an incident reading of f/8. (a) Reading at 4 m? (b) If the fill light alone reads f/4 at the subject while the key alone reads f/8, what is the lighting ratio?

• (a) Doubling distance = (2/4)² = 1/4 of the light = 2 stops less → f/8 → f/5.6 → f/4.
• (b) f/8 is 2 stops above f/4, so the key is 4× the fill. Total on the lit side = key + fill = 4 + 1 = 5 units; shadow side = fill = 1 unit → ratio 5:1, i.e. about 2.3 stops. (If the question defines the ratio as key:fill, the answer is 4:1 - state the convention you are using.)

Example 3 - Crop factor and angle of view. You own a 35 mm lens and shoot on APS-C (23.6 × 15.7 mm, crop 1.5).

• Equivalent focal length = 35 × 1.5 = 52.5 mm - a "normal" lens on that body.
• Horizontal angle of view = 2 arctan(23.6 / (2 × 35)) = 2 arctan(0.3371) = 2 × 18.63° = 37.3°.
• On full frame (36 mm wide) the same lens gives 2 arctan(36/70) = 2 arctan(0.5143) = 2 × 27.2° = 54.4° - visibly wider.

Example 4 - Hyperfocal distance for a landscape. Full-frame camera, 24 mm lens, f/11, c = 0.03 mm.

• H ≈ f²/(N·c) + f = (24 × 24)/(11 × 0.03) + 24 = 576/0.33 + 24 = 1,745 + 24 = 1,769 mm ≈ 1.77 m.
• Focus at 1.77 m and everything from about 0.88 m to infinity is acceptably sharp. At f/4 the same lens gives H = 576/0.12 + 24 = 4,824 mm ≈ 4.8 m (near limit ~2.4 m) - a clear reason landscapes are shot stopped down.

Example 5 - Sunny 16, flash GN and print size.

• Sunny 16 at ISO 200: f/16 at 1/200 s (nearest marked speed 1/250 s, so open slightly or use f/14).
• A flash of GN 36 (m, ISO 100) at 4 m: N = 36/4 = f/9. Move to 6 m: N = 36/6 = f/6; at ISO 400 (2 stops) the GN doubles to 72, giving N = 72/6 = f/12.
• A 24 MP file of 6,000 × 4,000 px prints at 300 ppi as 6,000/300 × 4,000/300 = 20 × 13.3 inches; at 150 ppi for a standing-distance poster, 40 × 26.7 inches.

Where it is used

• Advertising and e-commerce studios: Myntra, Nykaa, Amazon and Flipkart catalogue studios shoot hundreds of frames a day on fixed lighting ratios, tethered capture and colour-managed sRGB output - exposure consistency and white balance discipline are the hiring test.
• News, sport and documentary: The Hindu, Indian Express, PTI, ANI, Network18 photojournalists work in aperture or shutter priority with Auto ISO, spot or evaluative metering, and deliver IPTC-captioned JPEGs on deadline.
• Weddings and events: India's largest photography employer by headcount - fast primes, flash-ambient balance, HSS for daylight portraits, two-card backup, and 1,000-frame culls.
• Corporate, architecture and real-estate: tilt-shift or wide lenses with vertical correction, bracketing and blending for interiors, polarisers for glass and sky.
• Film, OTT and content roles: camera assistant, DIT, gaffer and stills photographer on shoots - the same lighting grammar (key, fill, rim, ratios, kelvin matching) carries into cinematography.
• Education, museums and heritage documentation: ASI and state archaeology projects, copy photography of artworks with cross-polarisation and CRI 95+ lighting, 300 ppi reproduction for print catalogues.

Interview questions

• Q: What is a stop, and how do the three controls relate to it? A: A stop is a factor of two in light; one stop can be gained by opening the aperture one f-stop, halving the shutter speed, or doubling the ISO - the exposure is the same, the side effects differ.
• Q: Why does f/2 let in four times the light of f/4? A: Transmission depends on the area of the aperture, which scales as 1/N²; halving the f-number quadruples the area.
• Q: Does focal length change perspective? A: No - perspective is set by camera-to-subject distance. A wide lens appears to distort only because it is used from close in; shooting the same framing from the same spot with any lens gives identical perspective.
• Q: How do you make light softer without buying a bigger light? A: Move the existing source closer, or diffuse and bounce it so its apparent size relative to the subject grows; wrap and shadow-edge softness follow from relative size.
• Q: Shutter speed controls what, when you mix flash with daylight? A: The ambient exposure. Flash duration is far shorter than the shutter time, so flash exposure is governed by aperture, ISO, power and distance - that separation is how you balance the two.
• Q: Why is your snow or white-backdrop shot coming out grey? A: The reflected-light meter is driving a bright scene to 18% grey; add positive exposure compensation, or meter with an incident meter or grey card.
• Q: What is the sync speed, and what happens above it? A: The fastest speed at which the focal-plane shutter is fully open (about 1/200-1/250 s); above it a dark band from the curtain appears unless high-speed sync is used, which pulses the flash and costs several stops.
• Q: Why shoot RAW over JPEG? A: RAW keeps 12-14 bit unprocessed sensor data, so white balance, exposure and highlight recovery are non-destructive; JPEG bakes in 8-bit processing and discards that latitude.
• Q: Why is f/22 not the sharpest aperture for a landscape? A: Diffraction softens the whole frame at very small apertures; focus at the hyperfocal distance around f/8-f/11 instead for both depth and resolution.
• Q: A client's product shot must show texture on a matte leather bag. Your lighting? A: A raking side light to skim the surface and cast micro-shadows, a reflector or low-power fill to hold shadow detail at about a 4:1 ratio, and a flag to keep spill off the background.
• Q: Who owns the copyright in photographs you shoot on a paid assignment? A: Under the Copyright Act, 1957 the photographer is the author, but for a commissioned photograph taken for valuable consideration, or under a contract of service, the commissioning party or employer is the first owner unless the contract provides otherwise - so put licence and ownership in the contract.
• Q: How would you match an LED panel to window light in one frame? A: Measure or match the colour temperature - gel or dial the LED to about 5,600 K daylight, set one custom white balance off a grey card under the mixed light, and check an LED with CRI 95+ so skin tones do not shift.

Common mistakes

• Treating a smaller f-number as a smaller opening, and so reversing every depth-of-field answer in the exam.
• Writing that a telephoto lens "compresses perspective" without adding that the compression comes from the greater shooting distance.
• Using N instead of N² in equivalent-exposure or inverse-square calculations - a factor-of-two error in stops.
• Pushing ISO to fix underexposure that a tripod, a wider aperture or a flash would have solved, then fighting noise in post.
• Judging exposure from the rear screen at full brightness instead of the histogram or zebras, and clipping highlights unrecoverably.
• Leaving white balance on auto in a mixed-light interior and shooting JPEG, which bakes the colour cast in permanently.
• Composing with the subject dead centre and the frame edges cluttered, with no headroom or looking room - the fastest portfolio rejection.
• Assuming a photograph needs copyright registration to be protected, or that the photographer always owns a commissioned shoot.

Related topics

Commercial photography: product, fashion and food · Videography and cinematography basics · Image editing and post-production workflow · Colour theory and colour management · Graphic design and layout principles · Visual communication theory and semiotics