Becoming Friends with Your Camera

Exploring perspective, focal length/zoom, and the center of projection through three mini‑studies.

Student: Eduardo Cortes • Course: CS180/280 — Fall 2025 • Date: September 2025

Overview

In this project I investigate how changing camera distance and focal length affects apparent geometry. I replicate three scenarios: (1) a close‑up selfie versus a stepped‑back, zoomed portrait; (2) architectural perspective compression along a street; (3) a classic dolly zoom (aka the Vertigo shot) created from a sequence of stills. Each study keeps subject scale roughly constant while changing the viewing geometry.

Part 1 — Selfie: The Wrong Way vs. The Right Way

Close & Wide ("Wrong Way")

Taken close to the face with a wide lens (or no zoom).
Close-up wide selfie
Notice exaggerated nose/forehead, receding ears: a perspective effect from short subject distance.

Back Up & Zoom ("Right Way")

Camera further away; zoomed in to match head size.
Stepped-back, zoomed portrait
Facial features look more natural; relative depth is less distorted.

Interactive Comparison

Drag the handle to compare close vs. backed‑up shots.
Close-up wide selfie (baseline) Backed-up zoomed portrait (overlay)

Reflection

Observation: When I increased the camera distance and used a longer focal length to keep the head the same size, the relative size of near vs. far facial features changed. The projection rays strike the face at narrower angles, reducing perspective exaggeration.

Why: Perspective is governed by camera position (center of projection), not by focal length alone. Changing focal length while holding position just crops/zooms the same projection. Stepping back actually changes the ray geometry through the scene.

Part 2 — Architectural Perspective Compression

Zoomed‑in From Afar

Telephoto from far away.
Telephoto view down street
Parallel depth layers appear “stacked”: classic telephoto compression.

Walk Forward, No Zoom

Closer camera position; wider field of view to match framing.
Wide view after walking forward
Near objects expand and recede more dramatically relative to far features.

Interactive Comparison

Drag to compare telephoto compression vs. wide nearby view.
Telephoto from far (baseline) Wide from near (overlay)

Reflection

Observation: In the telephoto shot, buildings and street features appear flattened; in the near wide shot, depth is emphasized.

Why: Again, the decisive change is camera distance. Telephoto doesn’t create compression by itself; it crops a projection from farther away, where rays to near and far objects are more parallel, reducing relative size change with depth.

Part 3 — The Dolly Zoom (Vertigo Shot)

Animation

Created by moving the camera backward while zooming in, keeping subject scale roughly constant.
Dolly zoom animation
Background appears to stretch while subject size remains constant — a striking shift in perspective with constant framing.

Process Notes

I captured 7 frames while physically dollying the camera backward and increasing focal length to keep the subject size constant. I then combined frames into an animated GIF. Frame count, steadiness, and consistent exposure/focus help the effect read cleanly.

Appendix — Method & Export Settings

Capture: Smartphone camera, exposure locked; for Parts 1–2 I matched subject scale between shots. For Part 3 I kept the subject centered and used markers where possible.

Exports: Photos saved as .webp at ~1600–2000px on the long edge; GIF at 10 fps, resized to ≤ 1200px width for web. (Animated WebP or MP4 offers better quality/size but GIF is used here per assignment.)