Close-focus adapter lens — reduces minimum focus distance for extreme macro work. Sharper than extension tubes, zero optical loss with quality glass.
Proximity Mask / Prox Mask
You need a close-up shot that your standard lens can't quite achieve — this is where you'd use a Proximity Mask. It's a small, high-quality auxiliary lens that you screw onto the front of your lens, drastically reducing the minimum focusing distance. Unlike cheap close-up lenses or macro filters, a genuine Prox Mask works with such minimal optical aberration that you won't see a visible loss in quality on set. The optics are precisely ground — this isn't eBay junk, but hardware for true macro work.
In practice, it looks like this: You have a 35mm or 50mm prime mounted, and suddenly you need details on an object that's only 15 centimeters from the sensor. Your lens normally won't focus closer than 30 cm — a classic problem. Instead of shifting the cut or working with optical tricks, you screw on the Prox Mask and instantly gain macro capability. The advantage over a true macro lens: you remain flexible. You don't change the entire lens, but adapt your existing one for the specific shot. This saves time and preserves your sensor plane.
Important to know: The mask works best with fast lenses — an f/2.8 or faster gives you enough light margin to still work even at extreme close ranges. With longer focal lengths (85mm and up), you'll notice less vignetting and aberrations. Conversely: With your standard zoom, you'll see optical flaws more clearly. The depth of field will be minimal — expect that at f/2.8 and a 20 cm distance, you'll only have 2-3 millimeters in focus. This isn't a disadvantage, but a creative choice. You'll need a stable rig and precise follow focus, unless your 1st AC is already a macro specialist.
Specifically in use: Beauty shots of surfaces, texture details, jewelry, small objects in extreme close-up — anywhere you need extreme macro without fisheye distortion or overly demanding lighting. The Prox Mask doesn't replace specialized macro optics, but it's the elegant emergency solution on set when you spontaneously need to get close and don't have your full equipment with you. When purchasing, pay attention to the quality grade — cheap versions have air bubbles in the lens or scratches that you'll see in the image later.