All of these lenses have a common feature. A manual aperture ring that clicks into place at varying intervals. Some click at every third stop and some at every half stop. Regardless of the interval it is an annoying feature that doesn’t help motion picture shooters at all. This feature is in pace for a couple reasons. Mostly to allow the user to feel the clicks and know how many stops are being adjusted without having to look at the scale (assuming you know where you started). Second, some manual aperture lenses are spring loaded to keep the blades tight and reduce any play in the actual aperture opening. The clicks keep the spring from pulling the aperture closed or open. Removing the “clicks” leaves a nice single, fluid movement that allows seamless aperture adjustments. You are probably asking why this is important… Keep shooting, you’ll find the need sooner than later. The procedure is different from lens to lens but always requires disassembling the lens to get to the mechanism that provides the clicks. For a better idea of what the difference is, here is a short video showing a lens without the procedure and with.
So is the de-clicking procedure a necessity? No. But it makes DSLR footage that much closer to pro motion picture. A goal all VDSLR shooters are aiming for.