We took the brand new DJI Osmo Action 4 out into the kind of lighting that usually makes action cams fall apart—low light, mixed contrast scenes, and fast-moving action—and we did it properly: side-by-side against the previous generation. Straight away, the low-light comparisons show the big story here: the image looks flatter at first glance, but that’s actually the point. You’re seeing more dynamic range, more detail held in highlights and shadows, and a cleaner image thanks to DJI’s improved signal-to-noise performance. A huge part of that is the new D-Log M profile. It’s a 10-bit option designed to spread color information more evenly, which gives us more flexibility in the grade—especially when the scene is messy (think leafy, noisy backgrounds and motion everywhere). We also break down what hasn’t changed (same familiar form factor, mounts, and user experience) and what DJI is clearly pushing: a more complete accessory ecosystem. And because it wouldn’t be an action cam review without it, we jumped to Sardinia for underwater tests—where the built-in color temperature sensor (in the “O” on the front) helps nail more accurate underwater color and reduce flicker. If you’re wondering whether this is the best action camera for your travel filmmaking kit—or whether it’s worth upgrading from Action 3—this is the real-world breakdown.