All Articles
41 articles and guides about optical design and lens engineering. Subscribe to New Articles
Cardinal Points of a Lensguide
May 1, 2026
A gentle introduction to focal, principal, and nodal points — the six reference locations that define how any lens forms an image.
Lens Dimensions and Distancesguide
May 1, 2026
A beginner-friendly tour of the five first-order distances — EFL, BFD, FFD, hiatus, and total track — that summarize a lens as a geometric object.
From Achromat to APO: Chromatic Correction, Optical Glass, and the Evolution of Color-Corrected Lensesarticle
Apr 29, 2026
The evolution of chromatic control in lenses
Pupil Geometry in Photographic Lenses9-part series
Apr 21, 2026
A series of primers on aperture stops, entrance pupils, exit pupils, and telecentricity — from the f-number definition through sensor compatibility, corner illumination, and the mirrorless design advantage.
- 1What Is the Entrance Pupil? The Aperture Your Lens Shows the World
- 2The Entrance Pupil as Projection Center — Perspective, Panoramas, and the "Nodal Point" Myth
- 3The Exit Pupil and Your Digital Sensor — Chief-Ray Angle, Microlens Arrays, and Color Cast
- 4Why Corners Go Dark — The Three Causes of Light Falloff in Photographic Lenses
- 5Telecentricity Explained — What It Actually Means and What It Costs
- 6Mirrorless vs. SLR Lens Design — How Mount Geometry Shapes Image Quality
- 7Working f-Number — Why Macro Photographers Lose Light
- 8The Aperture Stop in Practice: Entrance Pupil, Exit Pupil, and Telecentricity
Getting Startedguide
Apr 16, 2026
New to Surface & Stop? These primers explain how lenses work, what aberrations are, and how to get the most out of the interactive diagrams.
Helios in Glass: A Developmental History of Voigtländer's Heliar Lens Designs, 1900–2025article
Mar 29, 2026
A history of one of the more neglected fundamental lens designs
Aberrations In Depthguide
Mar 25, 2026
Advanced aberration concepts including higher-order effects, balancing strategies, and aspherical surfaces.
Understanding Aberrationsguide
Mar 25, 2026
An introduction to the optical aberrations that lens designers work to minimize — spherical, coma, astigmatism, and more.
How Camera Lenses Workguide
Mar 24, 2026
A gentle introduction to refraction, focal length, and how multiple glass elements combine to form an image.
Optics In More Detailguide
Mar 24, 2026
A deeper look at optical design principles including Petzval sums, field curvature correction, and retrofocus designs.
About Surface & Stoparticle
Mar 19, 2026
How this interactive lens visualization tool was built and what makes it unique.
About the Authorarticle
Mar 19, 2026
Meet the creator of Surface & Stop — photographer and optical science enthusiast.