Aputure has released several versions of their DEC Lens Adapters, but in case you're not familiar with what they are and how they work, i've put together this Product Overview video. This video specifically focuses on the brand new DEC Vari-ND Model (available in MFT and E-Mount), but is very similar to the other models - especially the LensRegain version which is a Focal Reducer (a.k.a Speed Booster) Lens adapter.

Who's it For?
The way the product DEC Lens Adapters are designed, I think primarily it should really appeal to camera operators that need the ability to adjust focus with a wireless remote. Obviously it's not at the level of a professional Wireless Follow Focus system, but it at least offers decent focus controls at a minimal cost in an incredibly compact form. Even cheap wireless follow focus systems can still run well over $1200 dollars and require additional rods to mount, and additional power to run the focus motors.

The wireless remote and clamp can be attached as a handle to your gimbal, on a Steadicam, end of a Jib, or even to just the Pan Handle of your Tripod. Additional features such as iris adjustment on your Canon EF (or compatible) lenses can be handy when you are transitioning a camera movement from indoors to outdoors, or to just change your DOF. But now with the new Vari-ND version (electronic variable ND Filter) you have another dimension in which you can control your exposure and all through a wireless remote.

About the Vari-ND Filter
Traditional Variable ND Filters placed on the front lenses use two rotating pieces of glass that cancel out light as you rotate. While this is simple and effective, there are some drawbacks to how much variation you can have, how much color shift happens, and most importantly how much softness occurs because of how the two additional pieces of glass affect the incoming light (image).

The ND Filter inside of the DEC Vari-ND Lens Adapter is NOT using two pieces of polarizing glass. and is instead using a single sheet of glass (with liquid crystals) and uses electricity to adjust and vary the amount of ND. This is similar to the technology found in the new Sony FS5 camera. Aputure also claims that there are no color shifts happening during the process of varying the amount of ND applied.

At the minimum ND8 you're looking at about 3 Stops of ND Applied. The darkest ND applied on the Vari-ND is about 11 stops. ND8 (3 Stops) is pretty dark and something you won't be using indoors. Outdoors, you'll find the the Vari-ND useful especially when shooting at F/2.8 or wider. You'll notice in my video test there are steps between what i'm actually calling out (stops between ND8 and ND16, etc). Aputure claims they may be able to add a firmware update that allows smooth ND transitions instead of the stepping it has now (similar to how the Sony FS5 operates).

Summary
The line of Aputure DEC Lens Adapters are certainly very unique and offers features in a form factor and price that can't be found in any other tool. You can visit their website for additional information about the complete line of Aputure DEC Lens Adapters (found here).

Aputure DEC - Lens Adapter + Vari-ND + Lens Regain