Getting Started
New to the optical bench? Surface & Stop lets you explore a lens before you know all the vocabulary. This guide gives you a quick tour, then points to short explanations of the ideas behind the diagram.
A Five-Minute Tour
- Open the Lens Library and choose any design that interests you.
- Move FOCUS and APERTURE below the diagram. Zoom lenses also provide a ZOOM control.
- Select a glass element in the cross-section to inspect its surfaces, glass data, and optical role.
- Use the ray and overlay controls to separate on-axis, off-axis, and chromatic behavior.
- Open ABERRATIONS & DISTORTIONS at the lower left of the diagram. Start with SUMMARY, then choose a focused analysis such as CHROMATIC, COMA, BOKEH, or DISTORTION.
- Copy the URL when you want to save or share the current view.
The available controls depend on the lens. A prime has no zoom slider, for example, and specialized movement or folded path controls appear only where the model supports them.
Reading The Viewer
| Control | What To Look For |
|---|---|
| Focus | Watch modeled lens groups move and see where ray bundles meet the image plane |
| Aperture | Compare which rays pass the stop and how the bundle changes as the lens is stopped down |
| Zoom | Follow changes in focal length, spacing, field, and group movement |
| Element selection | Inspect surface curvature, glass properties, and aspheric details |
| Analysis drawer | Move from a first-order summary to focused aberration and image-formation views |
| Diagram zoom | Enter ZOOM mode, then use the wheel or pinch gesture to magnify and drag to pan |
In diagram zoom mode, + and - change magnification, arrow keys pan, 0 resets the view, and Escape exits.
The viewer is a model of a patent prescription, not a photograph of a cutaway lens or a laboratory test of a production sample. Use it to understand the design and compare optical behavior; read About Surface & Stop for the provenance and analysis limits.
How Lenses Work
Start with refraction, focal length, and how multiple glass elements combine to form an image.
- How Camera Lenses Work — A gentle conceptual introduction
- Optics In More Detail — Deeper dive into ray behavior and element roles
Cardinal Points and Dimensions
Every lens, no matter how complex, can be summarized by a handful of reference points and distances along the optical axis. Once you know where they sit, you can predict where the image forms and how big it will be.
- Cardinal Points of a Lens — Focal, principal, and nodal points explained
- Lens Dimensions and Distances — EFL, BFD, FFD, hiatus, and total track
Aberrations
Real lenses are imperfect. Learn what aberrations are and why lens designers spend so much effort corralling them.
- Understanding Aberrations — What goes wrong and why it matters
- Aberrations In Depth — Quantitative treatment and correction strategies
Where To Go Next
- Browse the Lens Library by maker, inventor, assignee, patent year, mount, format, or focal length.
- Use COMPARE in the viewer's top bar to place two designs side by side with shared controls.
- Explore the Article Library for design histories and deeper guides.
- Browse Mounts to compare camera-side and lens-side interface geometry.