Wide 18mm vs. Wide 16mm II
The original Wide 18mm built up a loyal following for good reason. It sits in a sweet spot… wide enough to open up a scene, tight enough to still feel grounded and intentional. If you've been shooting with it, you already know what it does well.
The new Wide 16mm II helps refine that level of scenery. The extra two millimeters of width might not sound like much on paper, but in practice it gives you just a bit more breathing room to make a real difference when you're vlogging handheld, shooting talking heads outdoors, or trying to shoot interiors without backing yourself into a wall.
What the Wide 16mm II also brings is noticeably nicer background separation. Even though you're shooting wider than 24mm, the larger main camera sensor does real work here, giving you a focus falloff that actually feels pleasing rather than clinical. It brings in more light than the ultra-wide, handles low light better, and just produces images that feel more like what you'd expect from a proper wide lens.
The Wide 16mm II accepts a 67mm filter thread adapter, which opens up a whole workflow for more serious mobile shooters. Diffusion filters, variable NDs, circular polarizers - if you're shooting Apple ProRes and want the most out of your glass, this is where the Wide 16mm II steps ahead of its predecessor and really earns its place as a pro-level video lens. Pair it with the Tele 58mm lens that takes the same adapter, and you've got a genuinely powerful two-lens kit.
That said, the Wide 18mm isn't obsolete. If you already own it, it still holds its own, especially as part of a multi-cam setup where you want distinct focal lengths for different angles. Both lenses can comfortably coexist in a kit, each serving a slightly different role.