A Sony lens focus-hold button can be reassigned to a different function through the camera’s custom key menu, but only if the lens actually has that physical button, and only within the function list your specific camera body offers. Not every Sony lens includes a focus-hold button, and the list of assignable functions changes across camera generations and tiers, so the real task is confirming what your exact body and lens combination supports before you build a habit around it. This guide walks through identifying the control, finding the right menu, choosing a function that matches how you actually shoot, and checking that the assignment behaves the way you expect in both stills and video.

Identify the Physical Control

The focus-hold button is a small, usually round button set into the lens barrel, most common on Sony’s higher-end G and G Master lenses, particularly telephoto and super-telephoto models, where it is often duplicated at multiple points around the barrel so it stays reachable in both horizontal and vertical shooting positions. It is a separate control from the AF/MF switch, which changes the lens’s entire focus mode between autofocus and manual, and it is also separate from the camera body’s AF-ON button, which is typically used for back-button focus and starts or drives autofocus rather than freezing it.

Many consumer zooms and primes do not have a focus-hold button at all, so the first real check is physical: look at the lens barrel for a button distinct from the zoom ring, focus ring, and any AF/MF or stabilization switches. If your lens does not have this button, none of the reassignment steps below apply, and any focus-hold behavior has to come from a camera body control instead.

Check the Assignment Menu

Once you have confirmed the lens has a focus-hold button, the reassignment lives in the camera’s custom key or dial settings, typically under a menu section dedicated to lens buttons rather than body buttons. Sony separates this from the body’s own custom button menu because the lens button is a distinct hardware element that the body detects and remaps through firmware.

The exact menu path and wording differ across camera generations and sensor formats, and the list of functions available to assign is not identical across bodies, some older or entry-level models expose a shorter list than recent flagship bodies. Check your specific camera’s manual for the current menu location and the full list of options it supports rather than assuming a list you have seen for a different model applies to yours.

Choose a Task-Specific Function

The default behavior of the focus-hold button is usually to freeze the current focus distance for as long as it is held, which is useful when something briefly crosses your intended subject, or when you want autofocus to stop hunting for a moment without switching the lens to manual focus. That is different from assigning the button to a full AF/MF toggle, which changes the focus mode more permanently until you toggle it back, or from assigning it to trigger a focus aid such as a magnified view for manual confirmation.

  • Focus hold (default): temporarily freezes the current focus distance while the button is pressed, then autofocus resumes normally on release.
  • AF/MF toggle: switches the entire focus mode, useful when you regularly move between fully manual and autofocus work.
  • Focus aid or magnifier trigger: calls up a manual focus check tool, useful for static or macro subjects where you want to confirm focus visually rather than just hold it.
  • Other documented shortcuts: some bodies allow functions like Eye AF activation or exposure preview to be assigned to the lens button, depending on the model.

Match the function to a task you actually repeat. A wildlife or sports shooter who regularly loses a subject to a foreground obstruction benefits most from keeping the default hold function, while a shooter doing careful manual work on static subjects may prefer a magnifier or focus aid trigger instead.

Test Both Photo and Video Use

Sony bodies commonly let you set separate custom key assignments for still shooting and for movie recording, so a function assigned for photos does not automatically carry over to video, and in some cases the same physical button can behave differently or be unavailable depending on which mode you are in. After changing the assignment, physically test it in both modes rather than assuming the change applies everywhere.

  • Set the desired function under the still-shooting custom key menu, then shoot a short test sequence to confirm it behaves as expected.
  • Switch to movie mode and check the same button, since movie-specific custom key menus are often separate from stills on the same camera.
  • Note your original assignment before changing anything so you can restore the stock behavior if the new setting does not suit your workflow.