V-Ray Tip: V-Ray Physical Camera: Natural Exposure Workflow

Natural exposure starts with the V-Ray Physical Camera. Treat it like a real camera and let lighting, color, depth of field, and motion blur follow from physically correct settings.

• Exposure triangle basics
  • ISO: Sensor sensitivity. Keep low (ISO 100–200) for clean images; raise only if you need brighter exposure without changing depth of field or motion blur.
  • Shutter speed: Controls brightness and motion blur. Interiors often need slower shutters (1/15–1/4s); exteriors sit around 1/125–1/500s with V-Ray Sun/Sky.
  • Aperture (f-number): Controls brightness and depth of field. Higher f-numbers (f/8–f/11) for crisp architectural shots; lower (f/1.8–f/4) for shallow focus.
• Color and tone
  • White Balance: Use Kelvin presets to match the key light (e.g., 6500K for daylight, 3200K for tungsten). For HDRI, pick “Custom” and sample a neutral gray in frame.
  • VFB Camera Imager: Enable Exposure only for look-dev; for final shots, lock exposure in the Physical Camera for consistency across AOVs and comp.
  • Highlight control: Prefer preserving dynamic range (avoid hard clamping). Use VFB highlight burn or filmic tone mapping to tame bright windows without flattening.
• Practical workflow (fast and reliable)
  • Start: ISO 100, f/8, shutter 1/125s. Adjust shutter first to hit mid-gray while watching the VFB histogram.
  • Lock composition: Choose aperture for desired depth of field; then re-adjust shutter to maintain exposure.
  • Set white balance: Kelvin or pick-from-frame. Keep consistent across shots in a sequence.
  • Use real-world lights: Photometric IES, lumen-based VRayLights, and properly calibrated HDRIs produce predictable exposures.
• Matching plates and on-set references
  • Mirror set camera: Import real lens, f-number, shutter, and ISO from the shoot report or EXIF.
  • EV sanity check: If a daylight plate was shot around ISO 100, f/11, 1/250s, expect similar digital values with V-Ray Sun/Sky intensity at default.
• Depth of field and motion blur
  • DOF: Use sensor size and focal length that match your lens. Circle of confusion scales with sensor; APS-C vs full-frame will feel different at the same f-number.
  • Bokeh: Customize blade count, curvature, and bias for realistic highlights. Keep highlight burn under control to avoid harsh onion-ring artifacts.
  • Motion blur: Verify geometry and deformation blur settings. Shutter angle equivalence: 180° at 24 fps ≈ 1/48s shutter.
• Common pitfalls
  • Auto-exposure fights consistency: Great for look-dev, risky for sequences. Lock exposure before final.
  • Over-bright HDRIs: Normalize HDRIs or reduce intensity so camera settings remain in photographic ranges.
  • Crushed shadows: Raise light levels or open shadows in tone mapping—avoid boosting ISO excessively, which increases noise.
• Quick checklist
  • ISO low, aperture for DOF, shutter last for brightness.
  • Kelvin WB to match key; avoid “neutralizing” intended mood.
  • Use histogram and false color in VFB to spot clipping early.

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