Regarding what #2 said about those internal preamps, yeah, they are pretty rough. In my experience, keeping it simple is the way to go when you are panicking. I suggest the Rode VideoMic GO II Lightweight Directional Microphone. It uses plug-in power so no batteries to die mid-ceremony. Just set your camera gain to -12dB and it'll sound way cleaner!

Man, the GH5 internal preamps are honestly such a letdown for anything professional. I had major issues with that echoing cave sound when I first started out too. Unfortunately, the onboard audio just wont cut it for a wedding ceremony. Since you only have $150 and need something easy, here are a couple solid options:

• Rode VideoMic GO II Lightweight Directional Microphone - this is great because it doesnt even need batteries, so one less thing to stress about.
• <a href=" https://www.bhphotovideo.com/c/search?Ntt= Sennheiser+MKE+200+Directional+On-camera+Microphone&BI=8941&KBID=10361&SID=12345&DFF=d50" target="_blank" rel="nofollow sponsored">Sennheiser MKE 200 Directional On-camera Microphone - super compact and has a built-in shock mount so you dont get handling noise. Technically, you gotta make sure you go into the camera menu and set your mic level to -12dB or even lower. If you leave it on auto, the camera is gonna try to boost every tiny sound and you'll get that nasty hiss again. Dont worry tho, either of those mics will be a massive upgrade. You'll be fine!

Since you only have $150, you might want to consider the Deity V-Mic D3 Pro Super-Cardioid Shotgun Microphone. Honestly, the internal mics on the GH5 are terrible for something like a wedding. Be careful with the camera internal gain settings tho... if you crank them too high, you get a nasty hiss. I would suggest setting the camera to -12dB and using the gain knob on the back of the mic to get your levels right. Also, make sure to check your battery before the ceremony starts. Nothing worse than a dead mic halfway through the vows. If you want something simpler that doesnt need batteries at all, look at the Rode VideoMic GO II Lightweight Shotgun Microphone. It is cheaper and pretty much plug-and-play. Just remember to plug the cable in all the way or you wont get any audio at all. Wedding audio is stressful so keep it simple.