Sony a1 Receives Firmware 4.00 With Enhanced Focus Controls and Digital Signature Support

Firmware Update

by Nino LeitnerDecember 11^th, 2025

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Sony has released firmware version 4.00 for its flagship a1 mirrorless camera, bringing expanded autofocus options, video workflow enhancements, and Camera Authenticity Solution support. The update arrives weeks after the a7R V received similar improvements, while the comparable a7 IV update was suspended due to stability issues.

Nearly four years after launch and despite being succeeded by the a1 II, the original Sony a1 continues to receive meaningful updates. This v4.00 firmware for the Sony a1 brings many of the same improvements that recently arrived on the a7R V, expanding focus customization and adding professional-grade features for photographers and filmmakers working in demanding workflows.

New focus area options

The Focus Area menu gains several additions for precise autofocus control. The Spot section now includes both XL and XS sizes, while three new Custom slots (Custom 1, 2, and 3) allow photographers to define and instantly recall their own focus zone configurations.

The Tracking section receives parallel additions with Tracking: Spot XL, Tracking: Spot XS, and Tracking: Custom 1, 2, and 3 options. Combined, these give a1 users six configurable tracking zones, a substantial upgrade for sports, wildlife, and event photographers who frequently switch between subject types.

Display and file management improvements

Sony has adapted the display layout of shooting information for both horizontal and vertical viewing orientations, making the a1 more practical for vertical video or portrait-mounted applications.

File management receives notable improvements as well. Users can now simultaneously delete and rate images stored on both memory card slots, streamlining the culling process. The camera can also display folder and file names during playback for easier image identification.

FTP transfer enhancements

Professional photographers will appreciate enhanced FTP capabilities including the ability to cancel scheduled transfers for specific images during ongoing sessions. New Transfer & Tagging app settings enable automatic FTP transfer scheduling for protected images and automatic protection of successfully transferred files. These features require the latest app version and may have regional restrictions.

Camera Authenticity Solution

The update adds support for the Write Digital Signature function for movies, embedding cryptographic signatures into video files at capture to verify footage has not been altered. This feature requires a paid license, with availability timing for general customers yet to be determined. The feature addresses growing demand from news organizations concerned about content authenticity.

Security updates

Important security changes include removal of IPsec functionality (users should enable Access Authentication instead) and deprecation of WPA and WEP Wi-Fi protocols. Users must now use the more secure WPA2 or WPA3 settings when connecting to Wi-Fi networks.

Bug fixes

The update addresses an issue where continuous shooting may not resume for 1-2 seconds after a burst sequence ends, fixes a problem with the vertical grip multi-selector, and includes general stability improvements.

A word of caution after recent update issues

This release arrives during an eventful period for Sony firmware. Just weeks ago, Sony released similar updates for the a7R V (version 4.00) and a7 IV (version 6.00) with comparable feature sets. However, the a7 IV update was subsequently suspended after users reported serious stability issues, including repeated reboots and cameras entering power saving mode whenever the monitor was closed.

The a7R V update remains available alongside this a1 release. While we have no reports of issues with the a1 firmware 4.00 so far, cautious users may want to monitor community feedback before updating cameras used for critical work.

Issues with Sony firmware updates in the past? Let us know!

If you had any issues with firmware updates for Sony cameras in the past, let us know in the comments. There’s even a Reddit thread for that, thanks to one of our readers. We’ll do our best to address issues with Sony going forward.

We also discussed the issue in our last Focus Check podcast:

Update notes

Users on firmware 1.32 or earlier must first update to version 2.01 before installing 4.00. Sony recommends a fully charged battery with at least 51% remaining and advises detaching any vertical grip before updating. The process takes approximately 6 minutes.

Firmware 4.00 is available now from Sony’s support website.

Have you updated your a1 to firmware 4.00, and which feature are you most looking forward to using? Don’t hesitate to let us know in the comments below!