Review on K&F Concept 82mm Variable ND Filter ND2-ND32: Adjustable Lens Filter with Ultra-HD 28-Layer Coatings for Effective Water-resistant Photography (1-5 Stops) by Jeff Leu

This rating refers to the size 82 mm. I ran a simple experiment to test this filter. On a bright sunny day with a bright blue sky I focused the lens to infinity and left the exposure at aperture priority f2.8, without a filter I got a shutter speed of 1/4000s. Then I set the filter to the minimum setting (ND2 ) set, the shutter speed decreased to 1/1250 vs expected 1/2000, but with ND32 the shutter speed was 1/250 vs expected 1/125. Here are the full dates.1. Aperture constant f2.8, focus infinity - no filter (ND0) -> shutter 1/4000 - min. ND2 -> shutter 1/1250- ND4 -> Shutter 1/1250 (no change from ND2) - ND8 -> shutter 1/800 (expected 1/500) -ND16 -> shutter 1/500 (expected 1/250) - ND32 -> shutter speed 1/250 (expected 1/ 125). I repeated my experiment with an aperture of f22 and the result is f2.8. Also tried with shutter priority and got the same result. There are no changes between ND2 and ND4, and the maximum value is ND16 versus the declared ND32. I'm not sure if I received a bad copy, but I'm sending it back. There are no changes between ND2 and ND4, and the maximum value is ND16 versus the declared ND32. I'm not sure if I received a bad copy, but I'm sending it back. There are no changes between ND2 and ND4, and the maximum value is ND16 versus the declared ND32. I'm not sure if I received a bad copy, but I'm sending it back.