6 Don’t Zoom
As tempting as it is to close in on a subject with the iPhone’s built-in zoom, it’s best to avoid it in pretty much all scenarios. Unless you have a device with a dual-lens camera module (like the iPhone 7 Plus), the zoom isn’t optical — it’s just digitally enlarged. That leads to grainier and more pixelated videos. Not good.
A far better and more reliable option is to just move your iPhone closer to your subject. Both the picture and the audio will be better at this point. If getting up close and personal to your subject isn’t an option, you can always look into aftermarket telescopic zoom lenses. The results likely won’t be perfect, but they’ll be a lot better than optically zoomed video.