I remember being so stressed about muffled audio when I first got my a6400 for a trip. My first beach videos were basically unusable because of the wind. I ended up trying these two options:

• Sony ECM-G1 Shotgun Microphone is great because it doesnt need a cable. It just works.
• Rode VideoMicro Compact On-Camera Microphone is very reliable, tho you have to remember to plug it in.

Like someone mentioned, those tiny shotgun mics are the standard choice, but honestly... I'm gonna disagree slightly. In my experience shooting ceremonies over the years, a super directional shotgun can sometimes make a wedding sound kinda thin because it cuts out the music and the vibe of the room too much. I've tried many different setups and for a beginner with an a6400, I'd actually look at the Sony ECM-XYST1M Stereo Microphone. It slides right into the shoe on top of your camera and doesnt need any messy cables. Since it captures stereo sound, the vows and the background music will sound way more natural together. Its basically foolproof. If you're dead set on a shotgun tho, check out the Rode VideoMic GO II. Its got better tech than the entry-level ones and wont distort as easily when things get loud during the party.

> under $150 small enough to fit in a backpack works without me having to be a sound engineer Totally get the confusion, audio is a rabbit hole. Just wondering tho, how far back are you planning to stand during the ceremony? The distance makes a massive difference for what gear you actually need for a wedding. If you're looking for something that just stays on the camera, the <a href=" https://www.bhphotovideo.com/c/search?Ntt= Sennheiser+MKE+200&BI=8941&KBID=10361&SID=12345&DFF=d50" target="_blank" rel="nofollow sponsored">Sennheiser MKE 200 is a decent option. Its unique because the shock mount and windscreen are internal, so it wont snag on stuff in your bag. It handles up to 120 dB SPL which is plenty for a loud reception, and it uses a supercardioid polar pattern to focus on the subjects. But tbh, for a wedding, distance is your enemy. If you can find a deal, the Rode Wireless ME is basically the auto mode of microphones. It has a feature called GainAssist that automatically adjusts your levels so the audio doesnt clip if someone starts cheering. It plugs right into your 3.5mm jack and is way more effective for vows than any shotgun mic if you're standing 20 feet away. Its usually right around that $149 mark.