The microphone on a modern interchangeable lens camera is an afterthought. The body is designed for image quality. The audio capture exists because audio capture is required for video recording, and a body without one would not be a credible video camera. But the actual quality of the built-in audio is rarely a priority for the manufacturer, and the placement of the microphone on the camera body almost guarantees it will not produce useful recordings except in a narrow set of conditions.
What the built-in microphone is actually doing
On most mirrorless bodies, the built-in microphone is a stereo pair of small electret capsules. They sit on the top plate, near the hot shoe, exposed to the air. The capsules themselves are inexpensive components, sometimes the same generation of part used in consumer earbuds, and they are tuned for adequate intelligibility at a moderate distance from the camera.
This works for ambient sound. If you are recording a quiet outdoor scene and you want the rustle of leaves and the distant traffic, the built-in microphone captures it. The result will not be high fidelity, and the noise floor will be audible if you are listening on good headphones, but it is enough for context.
The trouble starts the moment you want directional audio. The built-in microphone hears everything, including the camera. Specifically, it hears the camera handling. The shutter button click, the focus motor whir, any twist of a control wheel, and the body itself moving in your hands all transmit through the camera body into the microphone capsules. On a video clip with a single person speaking three metres away, the breath of the operator behind the camera is often louder than the subject.
The image stabiliser problem
In-body image stabilisation systems shift the sensor on a tiny platform to compensate for camera shake. The actuators that drive this shift make noise, usually a low whirring tone, and that noise is mechanically coupled to the body of the camera. The built-in microphone picks it up. Most cameras include some filtering in the audio recording chain to suppress this, but the filtering also removes some of the legitimate audio in the same frequency range, leaving recordings that sound muffled.
This is not a fault that improves with the price of the camera body. Some of the most expensive bodies have the most aggressive stabilisation systems, which produce the most noise, which receive the most aggressive filtering, which produces the most muffled audio.
External microphones and the categories that matter
The fix for any of this is an external microphone, and the categories are simpler than the marketing makes them look. There are three useful kinds of microphone for camera-mounted video work, and they differ less by quality than by what they are designed to pick up.
A shotgun microphone is long and narrow, and it has a pickup pattern that is sensitive in front and rejects sound from the sides and behind. The Rode VideoMic series and the Sennheiser MKE 400 are common examples. Mount one on the camera’s hot shoe and the recording will favour whatever the camera is pointed at, which is often what you want. The trade is that shotguns sound thin compared to a microphone with a wider pickup, since they are aggressively directional and lose the room sound that fills in the body of a recording. For interviews shot at conversational distance, a shotgun on the camera is a workable compromise. For interviews shot at close range, a lavalier on the subject is almost always better. For a deeper look at how microphone types differ in pickup pattern and use case the buying guides from major retailers cover the technical side in plain language.
A lavalier is a small clip-on microphone, usually omnidirectional, designed to sit close to the subject’s mouth. Common wired options include the Rode Lavalier Go and the Sennheiser ME 2. Common wireless options include the Rode Wireless Pro and the DJI Mic. The lavalier picks up the subject clearly because it is close, and rejects most environmental sound because the subject is much louder than anything else at that distance. The downside is that the microphone is visible in the shot, the cable can be a nuisance for moving subjects, and wireless versions add the complications of radio frequency management or, in modern bodies, Bluetooth pairing.
An on-camera stereo microphone is a wider-pickup design, often two capsules in a coincident or X-Y arrangement, mounted to the hot shoe. The Zoom F1 with the SSH-6 attachment, or the Rode Stereo VideoMic, are examples. These produce ambient stereo recordings that are useful for music, performance, or scenes where the goal is to capture the space rather than a specific voice. They are not the right choice for dialogue, but they fill a niche the built-in microphone cannot.
Most consumer cameras accept external microphones through a 3.5mm TRS jack. The preamp behind the jack is, almost universally, mediocre. The noise floor is high enough that quiet sources sound noisy even with a clean microphone, and the gain stage is often non-linear in a way that compresses dynamic range unpredictably.
The workaround is to record into a dedicated audio recorder rather than into the camera. A small recorder like the Zoom H1n or the Tascam DR-05X has a much better preamp than any camera body, and it records to its own SD card while the camera records video to its own card. In post, the two recordings are synced, usually automatically based on the audio signal, and the result is markedly cleaner sound. The complication is that you now have two devices to keep charged and to start recording in sync, and the workflow is significantly less casual. For documentary or feature work this is normal. For run-and-gun shooting it is an irritation. A useful primer on improving camera audio with external preamps and recorders covers the workflow side of dual-system audio in production.
Headphones, and why monitoring matters
Bodies with a 3.5mm headphone jack let you monitor the audio the camera is actually recording, which is the only way to know if anything has gone wrong before you review the clip. Bodies without one require you to trust the meter and the post-recording playback, and the meter is often visible only in a small overlay that is easy to miss.
Cheap headphones are fine for monitoring. The point is not high fidelity, it is hearing the noise floor, hearing if a connector is loose, hearing if the wireless microphone has dropped out. Any closed-back headphone with reasonable isolation will do, and the cheap models from Sony, Audio-Technica, or KOSS are entirely adequate.
The practical reading
Built-in microphones are for situations where audio is unimportant or where ambient sound is fine. The moment a person is speaking, or the audio carries the meaning of the clip, an external microphone is the answer. The kind of external microphone depends on where the sound source is and how close you can get to it.
If the answer is interviews or talking heads, a wireless lavalier is the smallest investment that produces a large improvement. If the answer is ambient or documentary work where the camera is moving and the audio supplements the image, a shotgun on the hot shoe is reasonable. If the answer is music or performance, a dedicated stereo recorder synced in post is the best result for the budget.
None of this is the camera’s strong suit. Treat the audio side as a separate problem with separate tools, and the result will be markedly better than whatever the body produces on its own. The video side and the audio side need to be planned together, the way our notes on the lighting and capture considerations for live video describe, since timing decisions on one side affect the other.