Clarify capture time per pair

README.md

@@ -44,7 +44,7 @@ The location and scene names are anonymized. Identifiers such as `location_3`, `
 
 ## Capture Notes
 
-The main subset was captured with an emphasis on radiometric quality rather than speed. Each HDR image is built from two 14-bit, 9-exposure brackets with 1 EV spacing; the two brackets are averaged (stacking) to reduce noise before HDR merging. The images are then corrected for lens distortion and vignetting and stored as linear TIFF files.
+The main subset was captured with an emphasis on radiometric quality rather than speed. Each HDR image is built from two 14-bit, 9-exposure brackets with 1 EV spacing; the two brackets are averaged (stacking) to reduce noise before HDR merging. Including capture, bracketing, and repeated measurements, each of the 1,000 on/off pairs took roughly 5 minutes to record. The images are then corrected for lens distortion and vignetting and stored as linear TIFF files.
 
 The TIFF files retain the camera-captured EXIF metadata. This includes exposure information useful for recovering the capture conditions and for aligning the on/off measurements in physically motivated evaluations. Across a viewpoint, focus and aperture were kept fixed, and five on/off pairs were recorded with a shared base exposure setup.