Does the Continuously Variable ND Filter Spell the End of the Lens Iris?
The advent of the continuously variable neutral density filter (VND) raises an interesting issue: Do we still need a lens iris at all? The iris ring and underlying mechanism fitted with fragile rotating blades are at constant risk of damage from shock, moisture, and dust penetration; the iris itself adding cost and complexity while also reducing sharpness from diffraction artifacts when stopped down. The new Sony FS7 II features a VND that isn’t quite efficient enough to eliminate the lens iris entirely – but the day may be coming. For shooters, this could mean much better performing and sturdier lenses at lower cost.