ND Filter
An ND filter is a grey optical filter that reduces the amount of light reaching the sensor without altering the colors in the image.
What this is about
ND is what lets a film keep one look outdoors. The DP has locked a working stop for depth of field, midday sun delivers far more light than that stop allows, and the shutter is parked at 180 degrees for natural motion — so the only remaining lever is to darken the light itself. ND also travels to the windows: large rolls of ND gel on the glass bring a bright exterior down to the level the interior lamps can match.
A term only helps when everyone on set means the same thing by it — so what follows is how it is used, not a dictionary definition.
What runs differently here
In planning terms, that means:
- Densities are labelled in different systems: ND 0.6, ND4 and two stops can all mean the same filter.
- IRND versions block infrared as well, which digital sensors otherwise render as a magenta cast in dark fabrics.
- Variable ND filters are convenient but can cross-polarise into an X-shaped shadow on wide lenses.
With TillyGen
TillyGen's equipment list ties the ND set to the matte box and lens package, so day exteriors are not discovered without filters on the truck.
Change one constraint and the consequences travel through the whole plan: affected shots are flagged, the call sheet is regenerated, and nobody keeps working from yesterday's version.
Frequently asked
Why not just close the iris in bright sun?
Because the stop is a look decision. Closing down deepens depth of field, so the separation the film has used all week disappears in the exterior scenes.
How long does it take to get started with TillyGen?
A first project takes under an hour to set up. There is no configuration phase in which templates and fields have to be defined before the tool produces anything.
Can the results be exported?
Yes — as PDF for the crew, CSV for downstream systems and through the API for anything automated. The plan stays the source; the exports are views of it.