Rapido Technology +0.5 86mm Achromatic Diopter

• Diopter by Rapido Technologies

It’s time to look at Rapido’s +0.5 86mm achromatic diopter and how that’s a useful addition to any anamorphic filmmaker’s set. If you don’t care about it yet, I’ll show why you should. I’ll admit, the words “achromatic” and “diopter” are not the most appealing to beginners, so if you’re pushing through this one, I’m assuming you have some understanding about it.

Diopters are like glasses for your lenses. They allow you to see better closer. And anamorphics usually suck at seeing better closer. Most of them just love being at infinity!

The power of the diopter determines how close you see. I bet you’ve seen tons of diopter or close up sets before for super cheap. Like twenty bucks for four of them. So, what’s special about Rapido’s? Well, if you look at those cheap sets, you’ll see the power of those diopters ranges from +1 to +10.

In essence, diopters lock your infinity focus at a new distance. A +1 won’t allow you to focus further than 1m from the front of the lens. That’s three feet, if you’re American. Or British.

Three feet away from the lens is pretty close for most situations. If you’re trying to frame a medium close up, I bet you can’t do it from three feet away. And that’s where Rapido’s diopter power comes in. A +0.5 diopter locks your infinity at 2m or six feet, which is a much more workable range. Oh, these things also change your minimum focus, but since the math is more convoluted, you can use the calculator in the description.

So a low powered diopter is much more desired. They’re more flexible and still improve performance at close focus. That’s why you hear about the Tokina +0.4 or the Minolta +0.33, Vormax +0.5, SLR Magic +0.33 and so on.

Cool, we figured out what’s special about it being +0.5. Now the size: 86mm with threads on both sides. 86mm is pretty big. Like, really big,. This improves your odds of using it without vignetting.

The last piece of the puzzle, and the one that really hikes the price, is the “achromatic” part. Remember those cheap diopters we were talking about? Those are made of a single glass element. It means performance is only good in the center of the image and it degrades quickly towards the edges. Achromats are made of two glass elements that counter each other’s aberrations. The result is a much cleaner image, with great performance across the field. The downside is they’re much heavier than a single element diopter.

On this one the coatings are also pretty neutral, adding no side effects to the footage when flares show up. To give you some reference, the coatings on the SLR Magic are so strong, they create blue ghosts when flaring.

I’d say this is not a key piece of gear if you’re just getting started into anamorphics, but all of this info is good to have in the back of your mind. If you feel happy about the look of your shots and you want to push it a little further towards perfection, getting into diopters is the way to go.