Film latitude and clipping warnings
Detect when a metered spot would clip past the loaded film's latitude.
Where to find it
Viewfinder (drives the chips and zone ruler automatically when a reading clips)
Summary
Detection layer that powers the protect chips. Computes whether a metered spot would land at Zone IX.5 or above (highlight clip) or Zone I.5 or below (shadow crush) given the loaded film's latitude, and exposes that as the clipHigh and clipLow flags on each ZoneAnalysis.
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How it works
What it does
Every zone analysis carries two clipping flags. clipHigh is true when at least one spot lands at Zone IX.5 or above, meaning the highlight is past the film's headroom and will print as paper white with no detail. clipLow is true when at least one spot lands at Zone I.5 or below, meaning the shadow is past the film's toe and will print as paper black with no detail.
Why latitude matters
Each film stock has a finite range of stops it can record while keeping detail. Slide film holds roughly five stops; most negative films hold six to seven; some new tabular-grain stocks reach a bit further. The meter knows the latitude of the loaded stock and uses it to flag spots that fall outside the film's working range.
How it surfaces
The flags drive the protect chips (feature 4.10), the zone ruler colors (red for blown highlights, dark grey for crushed shadows), and the blink overlay (feature 4.11). You do not toggle this layer directly; it runs every time a reading is taken and feeds the visual warnings.
Pairing with development
When the meter flags both clipHigh and clipLow on the same reading, the scene's range is wider than the film can hold at normal development. That is the cue to either pull development to compress contrast (see the Development Advisor in 4.8), accept the clipping, or recompose.