Leica Firmware 4.0.1 Fixes SL3 Joystick AF and Bulb Mode Bugs

Leica Camera released firmware 4.0.1 for the SL3 and SL3-S on March 17, 2026, targeting two specific usability problems that had been tripping up shooters since the previous version.

The more immediately disruptive fix involves the joystick and autofocus behavior in video mode. When manual focus was selected, AF activation via the joystick had stopped working entirely. For anyone using the joystick to pull focus on a moving subject mid-clip, this was a genuine workflow killer. Version 4.0.1 restores that functionality: AF activation via the joystick is now possible again in video mode regardless of whether MF is the active focus setting.

The second fix addresses a nastier edge case in bulb mode. Under specific conditions, a long exposure could be triggered accidentally and, critically, could not be canceled once started. The trigger was a delayed activation of both pressure points on the shutter release, meaning a slightly hesitant press of the shutter could lock the camera into an exposure with no way out. That bug is now corrected.

Neither fix is glamorous, but both address genuine failure states rather than theoretical edge cases. The joystick AF regression in particular is the kind of thing that turns up immediately on any hybrid shooter who splits time between stills and video on an SL3.

It's worth noting that the article title references minor playback improvements, but the available documentation on 4.0.1 covers only the two fixes above. If Leica's full changelog includes additional changes, the official firmware page at Leica Camera's support site would have the authoritative details, along with the download file and installation instructions.

The 4.0 update for the SL3, released earlier, was a substantially larger drop that also touched the Q3. By comparison, 4.0.1 is clearly a targeted patch. Small version number, small scope, but if either of these bugs was affecting your shooting, it matters.