First Setup
What should you change on a Sony a6400 before your first shoot?
Format the card in the camera
Formatting builds the folder structure the camera expects and clears a card that has lived in other devices. The a6400 has one card slot — SD, or a Memory Stick PRO Duo from its era — so the card you format is the only copy of everything on it. On this generation Format lives in the Setup tab, not in a Shooting tab.
Shoot RAW — the only RAW it makes
Set File Format to RAW (or RAW & JPEG for a finished file beside it). Sony’s guide states that RAW images on this camera are recorded in the compressed RAW format — there is no RAW File Type menu, no Lossless Comp and no Uncompressed on this body. Files are 14-bit, dropping to 12-bit in continuous shooting, Silent Shooting, BULB and Long Exposure NR.
SteadyShot — the lens’s switch
Leave SteadyShot On for normal shooting — and know what it is: the a6400 has no in-body stabilization. The menu item switches the stabilization inside an OSS lens; Sony’s guide notes it cannot even be set when the mounted lens’s name lacks “OSS”. A non-OSS prime gets no stabilization from this body. On a tripod, turn it Off.
Save everything to Memory 1
Register the setup you just built to slot 1. From now on the mode dial’s MR position at 1 is your known-good camera — after any reset, one turn restores it. The body holds 3 sets (dial 1, 2, 3); M1–M4 live on the card, which is why saving comes after the format.
Put Format one press away
Add the items you will revisit — Format first — to My Menu. This generation’s menu is deep; your five items should not be.
Do the steps now, in order, then turn the mode dial to MR → 1 and confirm every setting stuck. That dial position is your camera from today on.