| ADC | Assistant/Director of Photography — a crew role designation |
| Altitude | The angle of a celestial body above the horizon, measured in degrees (0° = horizon, 90° = directly overhead) |
| Astronomical Twilight | Twilight when the sun is between 12° and 18° below the horizon; sky is almost completely dark |
| Azimuth | The compass direction of a celestial body, measured in degrees clockwise from North (0° = North, 90° = East, 180° = South, 270° = West) |
| Blue Hour | The period just before sunrise or just after sunset when indirect sunlight creates a blue cast — popular for architecture and cityscape photography |
| Booking | A confirmed (or tentative) photography engagement in Apex Lucis |
| Call Sheet | A document listing the day’s shooting schedule: times, locations, crew, and planned shots |
| Civil Twilight | Twilight when the sun is between 0° and 6° below the horizon; bright enough to work without artificial light |
| Contact | A person in your professional network who you work with (crew, talent, vendor) — distinct from a Client |
| Crew Roster | The list of people assigned to a specific booking |
| GBIF | Global Biodiversity Information Facility — a database of biodiversity observations used for wildlife species data |
| Galactic Centre | The central region of the Milky Way galaxy, which rises and sets at specific times/directions depending on location and date |
| Golden Hour | The period shortly after sunrise or before sunset when sunlight is warm and directional — widely considered the best light for photography |
| IAP | In-App Purchase — the mechanism used to purchase an Apex Lucis Pro subscription |
| Illumination | The percentage of the moon’s visible face that is lit by the sun (0% = new moon, 100% = full moon) |
| Invoice | A financial document requesting payment from a client for photography services |
| Julian Day | A continuous count of days used in astronomical calculations, starting from 1 January 4713 BC |
| KPI | Key Performance Indicator — a measurable business metric |
| Lead | A potential client enquiry that has not yet been converted to a booking |
| Mileage Rate | The cost-per-mile (or km) used to calculate travel expense claims |
| Nautical Twilight | Twilight when the sun is between 6° and 12° below the horizon; the horizon is still distinguishable at sea |
| New Moon | The lunar phase when the moon is not illuminated and not visible at night — optimal for Milky Way photography |
| P&L | Profit and Loss — a financial statement summarising revenue, expenses, and net profit |
| Package | A reusable pricing template defining a type of shoot and its base price |
| Permit | Official permission to photograph in a specific location, particularly for commercial or drone use |
| Pipeline | The sequence of stages a lead passes through before becoming a booking (Enquiry → Contacted → Quoted → Won) |
| Shoot Score | Apex Lucis’s composite rating (0–100) of current or forecast photographic conditions |
| Shot List | A pre-planned list of individual images to capture on a shoot |
| Studio Booking | A reservation of a hired commercial photography studio |
| Tidal Extreme | A high tide or low tide — the peak and trough of a tidal cycle |
| Transit | The moment when a celestial body crosses the meridian (due south in the northern hemisphere) — its highest point in the sky |
| Trip | A planned travel arrangement associated with a shoot, including accommodation and travel legs |
| VAT | Value Added Tax — a UK/EU consumption tax applied to invoices. Apex Lucis supports configurable tax labels for other regions (GST, Tax, etc.) |
| WeatherKit | Apple’s native weather forecast API used by Apex Lucis for weather data |