Select and compare multiple lenses — visualize image circle coverage across sensor formats
Image circles quoted at infinity (typically at f/22, per the manufacturer's brochure), except macro lenses which are quoted at their design magnification (annotated in the lens name, e.g. @ 1:1 or @ 1:5).
Only lenses whose image circle covers the largest selected format are clickable — smaller lenses are dimmed out. Selecting a larger format (e.g. 4×5 or 8×10) prunes any active lenses that no longer cover it.
Hover a circle (or a selected lens's name) to preview its coverage. Click a circle — or the ⊙ button on a selected lens — to pin its info box; boxes close via their × button or the ⊙ button again.
Where shown, weight (g) and filter threads come from manufacturer documents: Rodenstock spec list/catalogs/datasheets (incl. genuine rear filter threads on the two float lenses), Schneider-Kreuznach 1995 line spec sheets (Copal mount), ALPA Technical Data / 12 TC tables (ALPA-mount versions, helicoid included in weight). Nikkor/Fujinon and discontinued Rodenstock lines (AS-W, Apo-Ronar, GN 115/155/200) via the largeformatphotography.info table (Jan 2002), cross-validated against the manufacturer docs wherever both exist. Lenses without documented values simply show none. Rebuild: python3 add_specs.py (idempotent).
Center filter (name + EV correction) per the Schneider CF table, the Rodenstock LINOS catalog p.41 / CF brochure, and the ALPA lens tables. Distortion is the documented max % at the datasheet's field edge. MTF rad/tan is the verified datasheet read at the project's reference corners — film lenses: 20 lp/mm @ 62.5 mm image height (6×8 film + 18 mm shift, worst-case corner); digital lenses: 40–80 lp/mm @ 27.5 mm (33×44 sensor corner) — at the lens's peak aperture. Full method + per-lens sources: derived/LENS-NOTES.md and derived/digital-33x44.md.