AddendumDocument 16 of 21From the GFX 100S II field guide
Flash and
Continuous Light
Flash belongs mainly to controlled portrait and architectural work. Street, indoor sport, and Pixel Shift are usually better served without it. Start with the shutter type, then choose the light.
How to use this document
Use this when field conditions require specialist technique or failure-mode handling.
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Shutter-Light Rules
The GFX100S II can use sophisticated flash control, but the practical rule is simple: normal flash work starts with mechanical shutter and tested sync.
| Shutter state | Flash position | Recommended use | Risk |
|---|---|---|---|
| Mechanical | Normal flash use | C2 portrait, C5 architecture, controlled still life. | Watch sync speed; test trigger behavior before the subject arrives. |
| EFCS | Use carefully | Some portrait and tripod work where vibration matters. | Confirm flash compatibility and exposure uniformity with the chosen shutter speed. |
| Electronic | No normal flash | Silent street, Pixel Shift, vibration control without flash. | Do not expect ordinary flash timing to work as it does with mechanical shutter. |
| Mechanical + Electronic | Treat as mechanical-only for flash planning | Use only after confirming actual shutter behavior at the selected speed. | Automatic transition can break expectations if shutter speed crosses into electronic range. |
| Pixel Shift | Continuous light preferred | Daylight, stable LED, tungsten, or controlled continuous sources. | Flash recycle and output variation can create inconsistent source frames. |
Sync and Exposure Limits
The published sync speed is not the only thing to test. Trigger latency, HSS behavior, LED flicker, shutter type, and mixed light all affect the file.
Bank Compatibility
Use the bank to decide whether flash helps or gets in the way.
| Bank | Flash status | Continuous light status | Field instruction |
|---|---|---|---|
| C1 Landscape | Rare exception. | Natural light, twilight, moonlight, and light painting. | Use flash only for close foreground or deliberate night work. |
| C2 Portrait | Valid and often useful. | Valid for window, LED, and hybrid portrait work. | Save bank with flash off; enable flash per session. |
| C3 Street | Avoid. | Available light only unless the project is explicitly staged. | Flash breaks discretion and conflicts with the silent electronic-shutter posture. |
| C4 Indoor Sport | Avoid. | Venue light only. | Use mechanical shutter, flicker reduction, and shutter-speed choice rather than flash. |
| C5 Architecture | Important tool. | Useful for interiors, product-like details, and controlled spaces. | Supplement window balance, corners, surfaces, and dark materials; keep color consistent. |
| C6 Pixel Shift | Do not plan around it. | Preferred. | Use stable continuous light and avoid frame-to-frame illumination changes. |
C2 Portrait Lighting
Portrait flash is a session state. Keep the saved C2 bank neutral, then build the light for the subject, modifier, and room.
- Start with C2 bank default. Confirm Face/Eye behavior, shutter speed floor, and aperture before connecting the trigger.
- Switch to Mechanical Shutter for normal flash. Confirm shutter type before waking the trigger or transmitter.
- Choose ambient priority. Decide whether the room/window light is part of the image or only background tone.
- Set white balance from the light that defines skin. Use fixed Kelvin or custom WB from a grey card.
- Test at session distance. Check catchlight, iris sharpness, flash exposure, and background level before the subject starts working.
- Return the bank after the session. Trigger off, flash mode off, shutter restored if changed, wireless state checked.
Flash cannot fix missed eye focus.
Flash shortens the effective motion duration, but it does not move the focus plane. At f/1.7, test Eye Detection with the actual subject distance and contrast before relying on shallow-depth flash portraits.
C5 Architecture Lighting
Architecture lighting is usually corrective rather than theatrical. The goal is to make the space read accurately without visible lighting artifacts.
| Problem | Lighting approach | Camera state | Post note |
|---|---|---|---|
| Window too bright | Expose for windows, add interior flash or continuous fill. | Tripod, fixed WB, mechanical shutter for flash. | Keep a clean ambient frame for blend reference. |
| Dark material corner | Low-power bounced flash or large continuous source. | Maintain level/framing lock. | Avoid local color cast on timber, stone, or paint. |
| Mixed artificial light | Turn off problem sources where possible; otherwise choose the dominant source. | Custom WB from grey card in the working light. | Do not expect Auto WB to match bracket frames. |
| Reflective surfaces | Move the light, flag it, or use indirect bounce. | Review reflections at 100% before moving setup. | Retouching reflections is slower than fixing placement. |
| Exterior twilight | Usually no flash; use timing and bracketing. | Tripod, fixed Kelvin, mechanical or electronic based on exposure. | Preserve sky/building balance with exposure sequence. |
Pixel Shift Correction
Pixel Shift is multi-frame capture, but that does not make it a normal flash workflow.
Do not plan C6 around flash recycle.
For this guide, C6 uses continuous light. Any old wording that suggests increasing the Pixel Shift interval for flash recycle should be treated as a warning, not as the recommended setup. Pixel Shift subjects need stable continuous light, stable support, electronic shutter, IS/OIS off, and a clean combiner round trip.
Controlled-Light Workflow
When flash is valid, configure it as a temporary session state and remove it afterward.
- Start from the bank default with flash OFF. This prevents accidental firing later.
- Switch to Mechanical Shutter when using normal flash. Confirm this before connecting or waking the trigger.
- Set white balance from the actual light. For portrait and architecture, use a grey card or fixed Kelvin rather than Auto WB.
- Test one frame for banding, sync, and mixed-light color. Do not discover a lighting conflict after the subject or client has left.
- Check histogram and highlight warning after flash is added. Specular highlights and skin highlights need separate judgment.
- Return the camera to bank default after the session. Flash OFF, trigger off, and shutter state restored.
Lighting Failure Signatures
Most lighting problems are visible in the first test frame if you know what to look for.
| Symptom | Likely cause | Fix | Prevention |
|---|---|---|---|
| Black band across frame | Shutter speed above normal sync or wrong shutter state. | Return to 1/125s or slower; confirm mechanical shutter. | Run sync test before the session. |
| Flash does not fire | Electronic shutter, sleeping trigger, wrong channel, flash off, or incompatible mode. | Mechanical shutter, wake trigger, confirm channel/group, test from camera. | Keep a pre-session trigger checklist. |
| Color changes frame to frame | Auto WB, mixed light, LED cycling, or inconsistent flash output. | Fixed/custom WB; reduce mixed sources; increase recycle time or lower power. | Use fixed WB for all controlled lighting. |
| Pixel Shift combine artifacts | Light changed between source frames. | Reshoot with stable continuous light. | Avoid flash and moving daylight for C6 sequences. |
| Architecture light looks fake | Source too close, too hard, or wrong color. | Diffuse, bounce, move, reduce power, or match color temperature. | Use lighting to restore visibility, not announce itself. |
| Portrait skin looks brittle | Too much small-source contrast or over-sharpened high-frequency detail. | Use larger modifier, lower clarity/texture in post, protect highlight rolloff. | Judge skin at session distance and 100% before continuing. |
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