Sony a6400 Autofocus Not Working: Causes and How to Fix It

The Sony a6400 is a highly regarded mirrorless camera, celebrated for its superior image quality, rapid autofocus system, and user-friendly operation. It’s an ideal choice for capturing everyday moments and is equally adept at both photography and videography. However, even with its impressive performance, users might occasionally face challenges, such as autofocus not working properly. This article is here to assist if you’re experiencing this issue with your Sony a6400.

We will explore the various reasons why the autofocus might malfunction and offer practical solutions to resolve these problems. By identifying the root causes and applying the recommended fixes, you can restore the full functionality of your Sony a6400’s autofocus system and continue enjoying a smooth photography or videography experience. Let’s delve into troubleshooting the autofocus issues of the Sony a6400.

Table of Contents

Sony a6400 Autofocus Not Working: Causes and How to Fix It

1. Incorrect Focus Mode

One possible cause of Sony a6400 autofocus not working is using an incorrect focus mode. The Sony a6400 has several focus modes that can be selected depending on the shooting situation and the subject. For example, if you want to capture a moving subject, you should use the Continuous AF (AF-C) mode, which tracks the subject and adjusts the focus continuously. If you use the Single-shot AF (AF-S) mode, which locks the focus when you press the shutter button halfway, you might miss the focus if the subject moves after you lock the focus.

To change the focus mode, you can use the Fn button on the back of the camera and select the Focus Mode option from the function menu. Alternatively, you can assign the Focus Mode option to a custom button, such as C1 or C2, for quick access. You can also use the camera mode dial to select a shooting mode that matches the focus mode you want to use. For example, if you select the Tracking mode, the camera will automatically use the AF-C mode and track the subject you touch on the screen.

You should also make sure that you select the appropriate focus area for the focus mode you are using. The focus area determines how the camera selects the focus point within the frame. The Sony a6400 has several focus area options, such as Wide, Zone, Center, Flexible Spot, Expand Flexible Spot, and Lock-on AF. You can change the focus area by using the Fn button and selecting the Focus Area option from the function menu, or by assigning the Focus Area option to a custom button. You can also use the multi-selector or the touch screen to move the focus point or the focus area within the frame.

2. Manual Focus Mode Activated

Another possible cause of Sony a6400 autofocus not working is having the manual focus mode activated. The manual focus mode allows you to adjust the focus manually by rotating the focusing ring on the lens. This mode can be useful when you want to have full control over the focus or when the autofocus system fails to achieve sharp focus. However, if you accidentally switch to the manual focus mode, you might not notice that the autofocus system is not working.

To check if you are using the manual focus mode, you can look at the LCD screen or the viewfinder and see if there is a MF icon on the top right corner. You can also press the Fn button and see if the Focus Mode option is set to Manual Focus. If you want to switch back to the autofocus mode, you can either change the Focus Mode option to Single-shot AF, Continuous AF, or Automatic AF, or you can use the AF/MF switch on the lens (if available) to toggle between the autofocus and manual focus modes.

When you use the manual focus mode, you can also use some features to assist you in achieving sharp focus, such as MF Assist and Peaking Setting. MF Assist magnifies the image on the screen or the viewfinder when you rotate the focusing ring, so you can see the details more clearly. Peaking Setting highlights the edges of the in-focus area with a specific color, so you can see the focus point more easily. You can enable or disable these features by using the Fn button and selecting the MF Assist or Peaking Setting options from the function menu.

3. Autofocus Lock Engaged

A third possible cause of Sony a6400 autofocus not working is having the autofocus lock engaged. The autofocus lock is a feature that allows you to lock the focus on a specific subject or area and keep it locked even if the subject or the camera moves. This can be useful when you want to recompose the shot after focusing or when you want to prevent the camera from refocusing on a different subject.

To use the autofocus lock, you need to assign the AF On function to a custom button, such as AEL or C1. You can do this by using the Fn button and selecting the Custom Key option from the function menu, or by using the MENU button and selecting the Camera Settings2 tab and then the Custom Key option. Then, you can select the button you want to assign and choose the AF On function from the list.

Once you have assigned the AF On function to a custom button, you can use it to lock the focus. First, you need to switch the AF/MF/AEL switch lever to the AF/MF position. Then, you need to press the custom button that you have assigned to the AF On function. The focus will be locked, and the AF On icon will be displayed on the screen or the viewfinder. You can then recompose the shot and press the shutter button to take the picture. To release the focus lock, you can press the custom button again or switch the AF/MF/AEL switch lever to the AEL position.

If you accidentally press the custom button that has the AF On function assigned, you might not notice that the autofocus system is not working. To check if you have the autofocus lock engaged, you can look at the screen or the viewfinder and see if there is an AF On icon on the top right corner. You can also press the Fn button and see if the Focus Mode option is set to AF On. If you want to disable the autofocus lock, you can either press the custom button again or switch the AF/MF/AEL switch lever to the AEL position.

4. Low Light or Low Contrast Scenes

A fourth possible cause of Sony a6400 autofocus not working is shooting in low light or low contrast scenes. The autofocus system of the Sony a6400 relies on detecting the contrast or the phase difference of the light that enters the lens. When the light level is low or the scene has little contrast, such as a plain wall or a cloudy sky, the autofocus system may struggle to find a clear focus point and may hunt back and forth or fail to lock the focus.

To fix this problem, you can try the following solutions:

Use a lens with a larger maximum aperture, such as f/2.8 or lower. A larger aperture allows more light to enter the lens and improves the autofocus performance in low light situations. You can also use the Fn button and select the ISO option from the function menu to increase the ISO sensitivity, which makes the camera more responsive to the available light.
Use a lens with a faster autofocus motor, such as a Sony E-mount lens with a linear motor or a direct drive SSM (Super Sonic wave Motor). These lenses have a quicker and quieter autofocus operation and can achieve focus more easily in challenging conditions.

5. Lens Compatibility Issues

A fifth possible cause of Sony a6400 autofocus not working is having lens compatibility issues. The Sony a6400 has an APS-C sized sensor and uses the Sony E-mount system. This means that it’s compatible with any of Sony’s E-mount lenses or even third-party E-mount lenses like Sigma or Rokinon. However, some lenses may not support all the autofocus features or functions of the Sony a6400, such as Eye AF, Real-time Tracking, or Fast Hybrid AF.

To fix this problem, you can try the following solutions:

Check the compatibility of your lens with the Sony a6400. You can use the Lens Selector tool on the Sony website to see which lenses are fully compatible, compatible with restrictions, or not compatible with the Sony a6400. You can also check the best lenses for the Sony a6400 guide on Digital Camera World to see some recommended lenses for different types of photography.
Use a lens adapter if you want to use a lens that is not compatible with the Sony E-mount system, such as a Sony A-mount lens or a Canon EF lens. A lens adapter is a device that attaches to the camera body and allows you to mount a different type of lens. However, using a lens adapter may affect the autofocus performance and speed, and some autofocus features or functions may not work at all.

6. Dirty or Damaged Lens Contacts

A sixth possible cause of Sony a6400 autofocus not working is having dirty or damaged lens contacts. The lens contacts are the metal pins on the back of the lens and the camera body that allow the lens and the camera to communicate with each other. If the lens contacts are dirty, dusty, corroded, or bent, they may prevent the lens and the camera from sending and receiving the correct signals for the autofocus system to work properly.

To fix this problem, you can try the following solutions:

Clean the lens contacts with a soft, dry, lint-free cloth or a cotton swab. Gently wipe the contacts on both the lens and the camera body, making sure not to leave any residue or fibers behind. Do not use any liquids or solvents, as they may damage the contacts or the lens coating.
Check the lens contacts for any signs of damage, such as cracks, dents, or scratches. If you find any damage, you may need to replace the lens or the camera body, or have them repaired by a professional service center.
Make sure the lens is properly attached to the camera body. Turn off the camera and remove the lens. Then, align the white or orange marks on the lens and the camera body, and rotate the lens clockwise until it clicks into place. Turn on the camera and check if the autofocus system is working.

7. Camera Firmware Outdated

A seventh possible cause of Sony a6400 autofocus not working is having an outdated camera firmware. The camera firmware is the software that controls the camera’s functions and features. Sony may release firmware updates for the camera to improve its performance, fix bugs, or add new functions. If your camera firmware is not up to date, you may experience some issues with the autofocus system or other features.

To fix this problem, you can try the following solutions:

Check the current firmware version of your camera. You can use the MENU button and select the Setup tab and then the Version option to see the current firmware version of your camera. The latest firmware version for the Sony a6400 is Ver. 2.00, which was released on June 13, 2019 ². If your firmware version is lower than Ver. 2.00, you should update it to the latest version.
Download the firmware update file from the Sony support website. You can visit the Sony support website and enter the model name of your camera (ILCE-6400) to find the firmware update file for your camera. You can also use the links below to download the firmware update file for Windows or Mac operating systems. Save the file to the desktop of your computer (recommended).
Follow the instructions on the Sony support website or the video tutorial below to update the firmware of your camera. You will need a fully charged battery, a USB cable, and a computer to perform the firmware update. Do not turn off the camera or disconnect the USB cable during the update, as this may cause the camera to malfunction .