Project Optional. Used for the PDF report header.
Screen
Projector and lens
Seed database, 2026-05-17 — entries marked
(unverified) have estimated specs. See
shared/databases/projectors.json.
Positions
Porthole
Calculation mode
Results
Pick a projector to begin.
Configuration
Computed
How to read this Background on the inputs, drawings, and verdict.
The three modes
BSC answers one of three questions. Mode A (verify fit) is the default: you have everything and want to know if it fits. Mode B (find minimum porthole) tells you the smallest aperture that clean-fits the beam at your positions. Mode C (find projector position range) gives you the range of lens-centre heights that keep the beam clean through a fixed porthole.
Fit verdict tiers
Clean = all margins ≥ 10 mm. Tight = all margins ≥ 0 but at least one < 10 mm. Partial clip = at least one margin between −20 mm and 0. Fail = at least one margin worse than −20 mm.
Lens shift
When the projector lens centre is not on the screen's vertical centreline, the projector needs to shift the image vertically to land it centred on the screen. That's a derived requirement, expressed as a fraction of image height; if it exceeds the lens's published shift range, the projector physically needs to be repositioned. RP22 lens-shift evaluation rules are paid-tier; this free tier reports the geometric requirement.