Research-based preparation guide for using the FX3 for video and the A7 III for still photographs. No matched-camera test images or measured color differences are claimed here.
A photograph and a video clip from the same room can look surprisingly different even when both cameras display the same Kelvin number. White balance is one part of the chain. The light falling on the subject, the selected recording profile, the viewing transform, and the still-photo processing also affect the comparison.
Quick answer: establish a neutral reference under the subject's actual light, make a separate reference capture with each camera, and compare both through the intended editing and viewing workflow. Matching one number is a starting point, not a promise of identical color.
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Decide What “Matching” Means
My two bodies have different jobs: the A7 III makes photographs and the FX3 records video. The practical goal is coherent skin tone and a believable sense of the same location, not necessarily pixel-identical output. Decide whether the photographs will be processed from RAW and whether the video will be delivered through a finished-looking profile or a managed Log workflow.
Write that decision down before shooting. An FX3 Log image viewed without its intended transform should not be judged against a finished JPEG. Likewise, changing the still-photo preset after the shoot can change the comparison even if the camera's original white balance was consistent.
Find the Different Menu Paths
For the FX3 Ver.2-or-later guide, Sony lists MENU → Exposure/Color → White Balance → White Balance. For the A7 III, it is MENU → Camera Settings1 → White Balance. Both documentation sets describe preset, color-temperature/filter, and custom choices, but their menu organization is not identical.
Check the installed firmware and shooting mode before following a screenshot from another Sony body. Sony also notes that FX3 Cine EI and Cine EI Quick do not allow Auto white balance. That is a mode limitation, not necessarily a fault or a reason to reset the camera.
A Repeatable Neutral-Reference Routine
- Place a suitable neutral reference at the subject position, under the light actually reaching the face.
- Avoid a reflection, deep shadow, or a strongly colored bounce contaminating the reference.
- Use each camera's documented custom-white-balance procedure and confirm that the camera accepts the capture.
- Record a short FX3 clip and make an A7 III photograph that include the reference and the subject.
- Remove the reference without changing the lighting, then make the actual pictures.
- Repeat the reference whenever the relevant light changes.
Do not use an arbitrary white object just because it looks white to your eyes. A purpose-made neutral card provides a more deliberate reference than clothing, a painted wall, or a reflective desk. You still need to position it correctly and check the resulting image.
Reader Questions: Matching Kelvin, Green Tint, and Failed WB Captures
Why can the same Kelvin setting still look green or magenta?
Color temperature is not the whole adjustment. Sony's white-balance controls also provide color-filter and fine-adjustment controls. Compare the neutral reference through the intended viewing workflow before changing a camera-specific tint value. A number suggested for somebody else's LED light, profile, display, and room is not a universal FX3 correction.
First ask whether the cast appears in the recorded file or only on a monitor. Check the intended viewing transform, then compare the neutral reference and skin under a simpler light source. If the reference looks reasonable but one colored object changes strongly, investigate the lighting and processing instead of assuming that another global Kelvin change will fix everything.
Can I set custom white balance using a lens or body cap?
Do not treat an ordinary opaque cap as a calibrated neutral reference. Use the reference and procedure specified for the camera. For the FX3, Sony's custom-white-balance instructions require the white area to cover the capture frame. After capture, the camera displays calibrated color-temperature and color-filter values; confirm and register the intended setting.
What if the camera reports that the custom capture failed?
Sony describes a failed capture as a result outside the expected range, for example with an overly vivid subject. Although the camera can register that result, Sony recommends capturing again; an error value is indicated in orange. Recheck the reference, its lighting, and whether it actually fills the capture frame, rather than accepting an obviously wrong result because the camera lets you store it.
Repeat the same preparation separately on the A7 III using its own menu. Keep a reference still and clip from the same setup so that later adjustments have an identifiable starting point. This is a repeatable check, not a claim that the two bodies will produce identical color.
Question prompts: community discussions of matching Sony bodies at the same Kelvin setting and custom WB capture confusion on an FX30. The latter is a related-camera question, not an FX3 defect report; the instructions above are checked against the FX3 guide.
Mixed Light Is a Lighting Problem First
Consider an interview beside a window with a warm ceiling fixture on the opposite side of the face. A single global adjustment cannot independently neutralize two different sources on two sides of the subject. Moving the subject, controlling the window, switching off a conflicting fixture, or making the key light dominant may be more useful than repeatedly changing Kelvin.
In this hypothetical room, first choose which source should define the face. Make the reference under that source and assess whether the remaining background warmth is acceptable. The desired result may preserve atmosphere rather than make every object perfectly neutral.
Check a Complete Capture-to-Edit Example
Bring the still and clip into the applications that will actually finish the project. Apply the intended input interpretation and viewing transform to the video; process the photograph through its intended RAW or JPEG workflow. Compare them on the same display with consistent viewing conditions.
First check the reference, then skin, then background objects. If the neutral reference is close but skin still differs, do not assume white balance is the only remaining control. Review the profile, processing, exposure, and lighting. Avoid forcing a strong creative look into the diagnostic stage; it can hide the cause of a mismatch.
A Tiny Reference Log That Saves Guesswork
| Record | Example entry |
|---|---|
| Location and light | Interview room; window controlled; key light unchanged |
| Camera role | FX3 video / A7 III photographs |
| Reference files | Clip and still filenames from the same lighting setup |
| Processing | Named video transform and still-photo preset |
| Recheck trigger | Subject moves or daylight changes |
These entries are an example record, not a report from a completed shoot. The important habit is preserving enough context for the editor to understand why two files should be compared.
Keep the Camera Jobs Clear
Use the FX3 interview checklist for the wider recording rehearsal and the A7 III photo setup guide for stills. If one lens is being swapped between the bodies, the shared-lens planning guide helps prevent missed coverage while the lens is on the other camera.
Official references: Sony's FX3 White Balance and A7 III White Balance documentation. Use the guide that matches the body and firmware rather than borrowing settings from a newer model.