Sony a6400 - User Manual

The ExpoDisc is a photographic accessory designed to assist photographers in achieving accurate custom white balance settings across various Sony camera models. By providing a standardized method for capturing incident light, the ExpoDisc helps cameras interpret colors more faithfully, leading to more natural and consistent image rendering under diverse lighting conditions.

Function Description

The primary function of the ExpoDisc is to facilitate the creation of a custom white balance preset within a camera. Instead of relying on the camera's automatic white balance or predefined presets, which can sometimes misinterpret complex lighting, the ExpoDisc allows the camera to measure the actual color temperature of the light falling on the subject. This measurement is then used to establish a precise white balance reference, ensuring that white objects appear truly white in the final image, and all other colors are rendered accurately in relation to that white point.

The process typically involves attaching the ExpoDisc to the front of the camera lens. The photographer then aims the camera, with the ExpoDisc attached, towards the light source illuminating the subject. The ExpoDisc acts as a neutral diffuser, allowing only the incident light to pass through to the camera's sensor, effectively "telling" the camera what true white looks like under those specific lighting conditions. Once the measurement is taken, the camera stores this custom white balance setting, which can then be applied to subsequent photos taken in the same lighting environment. This method is particularly beneficial in mixed lighting, challenging artificial light, or situations where color accuracy is critical, such as product photography or portraiture.

Usage Features

The ExpoDisc is designed for straightforward integration into a photographer's workflow, with specific steps tailored to different Sony camera models.

Manual Focus Mode Requirement: For most Sony cameras, the initial step involves setting the camera to Manual Focus mode. This ensures that the camera's autofocus system does not interfere with the white balance measurement process, which relies on capturing a uniform light reading through the ExpoDisc.
Exposure Setting Flexibility: Users can set the camera's exposure either automatically using "P," "S," or "A" modes, or manually in "M" mode. This flexibility allows photographers to maintain their preferred exposure control while still utilizing the ExpoDisc for white balance calibration. The key is to ensure an appropriate exposure for the white balance measurement itself, as an underexposed or overexposed reading can lead to inaccurate results.
Menu Navigation for Custom White Balance: The procedure involves navigating through the camera's menu system to access the "White Balance" settings. Depending on the Sony model, this might involve selecting "Custom Setup," "Custom 1 - Custom 3," or a dedicated "WB" button. The ExpoDisc guides the camera to create a new custom white balance preset within one of these available slots.
Targeting the Light Source: A crucial step is to aim the camera, with the ExpoDisc attached, in the appropriate direction for the given lighting condition. This means pointing the ExpoDisc towards the primary light source illuminating the subject, ensuring that the camera measures the light that will actually fall on the scene. The ExpoDisc Instruction Manual provides detailed guidance on optimal aiming techniques for various lighting scenarios.
Calibration Confirmation: After initiating the white balance measurement (often by pressing the center of the control wheel or the shutter release button), the camera typically provides feedback. This can include a shutter sound beep, the display of calibrated values (Color Temperature and Color filter), or a visual confirmation that the white balance has been successfully registered. This immediate feedback helps users confirm the success of the calibration.
Error Handling: The system includes an error message, "Custom WB error," which indicates that the white balance could not be set accurately. This usually points to an issue with the exposure during the measurement. Users are prompted to adjust their exposure and reattempt the white balance setting, ensuring that the camera receives sufficient light through the ExpoDisc for a proper reading.
Memory and Retention: Once a custom white balance setting is registered, it is memorized by the camera and remains effective until a new setting is registered in the same custom slot. Some Sony models allow for saving multiple custom white balance references (e.g., Custom 1, 2, or 3), providing flexibility for photographers working in environments with different lighting setups.
Post-Calibration Workflow: After successfully setting the custom white balance and removing the ExpoDisc, users can return the camera to autofocus mode (if desired) and begin shooting. The camera will then apply the precisely calibrated white balance to all subsequent images, ensuring consistent and accurate color rendition.

Maintenance Features

The ExpoDisc itself is a passive device with minimal maintenance requirements, focusing primarily on ensuring its optical clarity and physical integrity.

Cleaning: As an optical accessory, the ExpoDisc should be kept clean to ensure accurate light transmission. Dust, fingerprints, or smudges on its surface can interfere with the light measurement, leading to inaccurate white balance readings. Regular cleaning with a soft, lint-free cloth, such as a microfiber lens cloth, is recommended. For more stubborn marks, a specialized lens cleaning solution can be used sparingly.
Storage: Proper storage is essential to protect the ExpoDisc from damage and contamination. It should be stored in a protective pouch or case when not in use, shielding it from dust, scratches, and impacts. Avoiding extreme temperatures and humidity will also help preserve its material integrity over time.
Handling: The ExpoDisc should be handled with care to prevent physical damage. Dropping it or subjecting it to excessive force could crack or deform the diffuser element, compromising its ability to accurately measure incident light. Attaching and detaching it from the lens should be done gently to avoid scratching the lens or the ExpoDisc itself.
No Electronic Components: Since the ExpoDisc is a non-electronic device, it does not require batteries, firmware updates, or complex troubleshooting related to electronic malfunctions. This simplifies its maintenance and ensures long-term reliability as a photographic tool. Its durability is primarily dependent on the user's care in handling and storage.

In summary, the ExpoDisc is a simple yet powerful tool for achieving precise custom white balance, enhancing color accuracy and consistency in photographs taken with Sony cameras. Its ease of use, coupled with minimal maintenance, makes it a valuable accessory for photographers seeking professional-grade color rendition.

Sony a6400 Specifications

General

Sensor	APS-C CMOS
Megapixels	24.2 MP
ISO Range	100-32000 (expandable to 102400)
Continuous Shooting Speed	11 fps
Connectivity	Wi-Fi, NFC, Bluetooth
Image Processor	BIONZ X
Battery	NP-FW50
Weight	403 g (body only)
Autofocus Points	425 phase-detection / 425 contrast-detection points
Video Resolution	4K up to 30p
Viewfinder	2.36 million-dot OLED electronic viewfinder
Screen	3.0-inch tilting touchscreen LCD
Dimensions	120.0 x 66.9 x 59.7 mm
Battery Life	Approx. 360 shots (LCD monitor)