LightScope: Light & EV Meter3.4

LightScope is a comprehensive solution providing professional light measurement and analysis using your iOS device's camera sensor.

【Key Measurement Features】
. Illuminance (lux) Measurement: Calculates accurate illuminance by analyzing EXIF data from the camera sensor. Illuminance is derived using the formula: (F-number² / (Exposure Time x ISO)) x Calibration Factor.
. Exposure (EV) Calculator: Converts measured illuminance to EV and suggests proper exposure combinations in standard stops for your ISO and aperture (or shutter) settings.
. Luminous Intensity (candela) Calculation: Automatically calculates the luminous intensity of a light source based on the set distance. Uses the formula: Illuminance (lux) x Distance².
. Color Temperature (K) & Tint Analysis: Precisely measures the light source's color temperature (1500K~15000K) and tint (green-magenta bias) by analyzing the camera's white balance sensor data - useful for identifying fluorescent and LED lighting.
. Real-time Histogram: Visualizes the balance of shadows, midtones, and highlights through 16-level brightness distribution analysis.
. Contrast Ratio Measurement: Evaluates the brightness ratio between bright and dark areas of a scene (based on 10th/90th percentiles) according to WCAG accessibility standards.
. Noise Measurement (SNR): Calculates the signal-to-noise ratio in dB to evaluate image quality in the shooting environment.

【Advanced Features】
. Image Capture and Storage: Captures camera images at the time of measurement and stores them with measurement data.
. Full-screen Image View: Zoom, pan, and rotate captured images for detailed inspection.
. Gallery Saving: Save captured images to your device's photo library.
. Measurement History and Trends: Save all measurements chronologically and chart trends for lux, EV, color temperature, contrast, and SNR.
. Continuous Logging: Automatically record measurements at a set interval (1-60s) - great for lighting design and site surveys.
. Full-Resolution Image Storage: Keep captured images at original quality for detailed inspection and gallery saving.
. Export All History: Export every measurement as a CSV file or a PDF report.
. Notes & Location Tags: Attach notes to measurements and optionally save the measurement location.
. Home Screen Widget: See your last measurement (lux, color temperature, contrast, SNR) right on the home screen.
. Camera Full-screen Mode: Hide panels to focus on the camera view while checking key measurements via a mini info panel.
. Measurement Lock: Freeze exposure and white balance for stable, steady readings.
. Spot Metering: In full-screen mode, tap anywhere to meter around that point.
. Perfect Dark/Light Mode Support: All UI elements automatically adapt to the system theme.

【User Settings】
. Calibration Wizard: Enter a reading from a reference lux meter and the calibration factor is calculated automatically. Manual slider adjustment is also available.
. Distance Setting: Set the distance to the light source for precise luminous intensity (cd) calculations.
. Front/Rear Camera Selection: Choose the appropriate camera for your measurement situation.

【Technical Features】
. Support for measuring various light source types: natural light, LED, fluorescent, incandescent, etc.
. Color temperature and tint sourced directly from the camera ISP's white balance estimation for reliable readings
. 10-frame moving average filter for measurement stabilization
. Center-weighted or spot (tap-to-meter) analysis for accurate evaluation of the main subject
. Automatic exposure quality assessment based on histogram analysis

Perfect tool for photographers, videographers, lighting designers, UI/UX developers, and anyone who needs accurate light measurements.

Version History iPhone Duo support.

• Unfold and the screen splits in two — camera preview on the left, readings on the right. The divider follows the hinge position the device reports
• On the folded outer screen, all six readings (illuminance, exposure, luminous intensity, color temperature, contrast, noise) still fit without scrolling

The metered area is now exact.
• The rectangle on screen matches the region the camera actually measures, instead of an estimate that drifted with the screen's aspect ratio
• When the metering point sits near an edge, the rectangle is clipped just as the sampling is
• If the metered area ends up hidden behind a screen element, it turns red to tell you

Also
• Location and photo permission prompts are now translated into Korean and Japanese 3.4 5d ago The measuring screen is new, in two modes.

• Instrument — read all six values at once without scrolling: illuminance, exposure (EV), luminous intensity, color temperature, contrast and noise. The camera preview and the metered area sit at the top
• Viewfinder — the whole screen becomes the preview and you meter exactly where you aim. Switch modes with the left toolbar button
• Opaque panels, so values stay readable in bright daylight
• All six toolbar buttons are now labeled

Grow light measurement
• PPFD — pick your light source and the app converts illuminance (lux) to PPFD. Turn it on in Settings → Grow Light
• DLI (Pro) — daily light integral from your light hours
• 8 light-source presets plus a custom conversion factor (Pro)
• PPFD is saved with your history and included in CSV export

Note: PPFD is an estimate derived from illuminance, not a spectral measurement. For precision growing, a dedicated PAR sensor is recommended.

Also
• Trend charts now use your full history on the free tier (the list still shows the latest 10)
• Fixed a case where illuminance could be computed incorrectly 3.3 Sep 7 A first-run guide now shows what LightScope can do before you start.

• First-run guide — explains how the camera measures light
• Pick a time range directly on the history chart; your choice is remembered
• Clear message instead of an empty chart when a range has no readings
• The Pro screen now leads with the feature you just reached for 3.1 Aug 26 Improved the accuracy and reliability of measurement features.

• Fixed the calibration wizard's 3-second measurement never completing
• Improved spot metering — tap the screen and lux, exposure (EV) and candela are re-measured at that point
• Measurement lock now freezes the preview as well as the readings, and saved photos match the locked moment
• Fixed the Pro screen sometimes failing to load pricing, and added a retry button 3.0.1 Aug 12 LightScope is now free! If you bought the app before, all Pro features unlock automatically.

Massive 3.0 update:
• Exposure (EV) calculator with shutter speed suggestions for your ISO and aperture
• Improved color temperature engine + tint (green-magenta) display
• Calibration wizard — auto-calibrate against a reference lux meter
• Spot metering · Measurement lock (AE/AWB)
• Continuous logging (1-60s interval)
• Export all history as CSV/PDF
• Full-resolution image capture
• Notes & location tags
• Home Screen widget 3.0 Aug 11 LightScope is a comprehensive solution providing professional light measurement and analysis using your iOS device's camera sensor.

【Key Measurement Features】
• Illuminance (lux) Measurement: Calculates accurate illuminance by analyzing EXIF data from the camera sensor. Illuminance is derived using the formula: (F-number² / (Exposure Time × ISO)) × Calibration Factor.
• Luminous Intensity (candela) Calculation: Automatically calculates the luminous intensity of a light source based on the set distance. Uses the formula: Illuminance (lux) × Distance².
• Color Temperature (K) Analysis: Precisely measures color temperature in the range of 1500K~15000K by converting RGB values to XYZ color space using McCamy's formula.
• Real-time Histogram: Visualizes the balance of shadows, midtones, and highlights through 16-level brightness distribution analysis.
• Contrast Ratio Measurement: Evaluates the ratio between the brightest and darkest parts of a scene according to WCAG accessibility standards.
• Noise Measurement (SNR): Calculates the signal-to-noise ratio in dB to evaluate image quality in the shooting environment.

【Advanced Features】
• Image Capture and Storage: Captures camera images at the time of measurement and stores them with measurement data.
• Full-screen Image View: Zoom, pan, and rotate captured images for detailed inspection.
• Gallery Saving: Save captured images to your device's photo library.
• Measurement History and Trends: Save all measurements chronologically and visualize trends with graphs.
• Camera Full-screen Mode: Hide panels to focus on the camera view while checking key measurements via a mini info panel.
• Perfect Dark/Light Mode Support: All UI elements automatically adapt to the system theme.

【User Settings】
• Illuminance Calibration: Adjust the calibration factor for more accurate measurements based on your environment.
• Distance Setting: Set the distance to the light source for precise luminous intensity (cd) calculations.
• Front/Rear Camera Selection: Choose the appropriate camera for your measurement situation.

【Technical Features】
• Support for measuring various light source types: natural light, LED, fluorescent, incandescent, etc.
• Algorithm optimization for stable color temperature calculation even in low-light environments
• 10-frame moving average filter for measurement stabilization
• Center-weighted image analysis for accurate evaluation of main subject quality
• Automatic exposure quality assessment based on histogram analysis

Perfect tool for photographers, videographers, lighting designers, UI/UX developers, and anyone who needs accurate light measurements. 2.0 05/13/2025 Added the ability to save a measurement list 1.4.0 12/07/2023 Multi language support 1.3.1 01/29/2022 Added features and fixed errors. 1.3 07/30/2021 Added features and fixed errors. 1.2.1 07/27/2021 Fix some bug and add functions 1.2 07/23/2021 Fix some bug and add functions 1.1 07/19/2021 Fix some bug and add functions 1.0.3 07/11/2021 Fix some bug and add functions 1.0.1 07/02/2021 1.0 07/01/2021