K&F Concept ND2-ND400 Blue Multi-Coated Variable ND Filter 82mm, 1 8.6 Stops

If you shoot photo (or specifically video) outdoors in the sunlight, you NEED a variable ND filter.For video, if you're shooting 30 FPS, you need to keep your shutter speed at 1/60 (because of the 180 rule) for natural blur and smoothness. If you want a nice blurry background at f/2.8, even at ISO 100, there's a great chance your image will be horribly exposed. Your only options are to increase the shutter speed (and compromise the natural look with distracting "choppiness") or crank up to f/16, which will flatten your image and get rid of that blurry background you wanted!In comes the variable ND filter. When applied, like variable sunglasses, it allows how much light passes through, kind of like an intimidating bouncer at a night club. So just twist the ring on ... MoreIf you shoot photo (or specifically video) outdoors in the sunlight, you NEED a variable ND filter.For video, if you're shooting 30 FPS, you need to keep your shutter speed at 1/60 (because of the 180 rule) for natural blur and smoothness. If you want a nice blurry background at f/2.8, even at ISO 100, there's a great chance your image will be horribly exposed. Your only options are to increase the shutter speed (and compromise the natural look with distracting "choppiness") or crank up to f/16, which will flatten your image and get rid of that blurry background you wanted!In comes the variable ND filter. When applied, like variable sunglasses, it allows how much light passes through, kind of like an intimidating bouncer at a night club. So just twist the ring on the filter and you can achieve your shot perfectly!With this specific filter, two small things bummed me out:1. The ring doesn't have actual stops, just continuous rotation so you can't really keep track of the specific amount of light you're letting in.2. When the filter is on my Tamron 28-75 2.8 lens, I can't put the lens cap on at the same time. Not a deal breaker, but annoying when you want to quickly take a picture or shoot some video.But for the price, it's hard to argue this isn't a great purchase.

I'm just a novice photographer, with limited experience using filters. That being said, I know my way around exposure settings and fairly literate with the technical specs of my cameras.I wanted to take some smooth pictures of waterfalls and saw this variable ND filter with good reviews. On the item description page, there's plenty of warnings to make sure you buy the right filter thread size for your camera, which seems pretty obvious. However, they don't mention that this ND filter is poorly suited to wide angle lenses. For reference, I had paired this filter with a Zeiss Touit E 12mm f/2.8 mounted on a Sony a6500.After coming back from vacation, I realized that many shots I took with the filter mounted had pretty poor light uniformity. I did notice while taking ... MoreI'm just a novice photographer, with limited experience using filters. That being said, I know my way around exposure settings and fairly literate with the technical specs of my cameras.I wanted to take some smooth pictures of waterfalls and saw this variable ND filter with good reviews. On the item description page, there's plenty of warnings to make sure you buy the right filter thread size for your camera, which seems pretty obvious. However, they don't mention that this ND filter is poorly suited to wide angle lenses. For reference, I had paired this filter with a Zeiss Touit E 12mm f/2.8 mounted on a Sony a6500.After coming back from vacation, I realized that many shots I took with the filter mounted had pretty poor light uniformity. I did notice while taking the photos that rotating past a certain point produced noticeable unevenness, but the effect was less/not noticeable when I turned the ND down. However, upon checking the images on a computer monitor, it was obvious that the brightness is not uniform.I asked the seller about the issue and copied/pasted their response below:"Darkness is a common issue with wide angle lenses and variable ND filters. Physics limit the capabilities of variable ND filters on wide angle lenses. When you enter the edge of the max range,the darkness may appear on your image. Because you are using it beyond its capability according to the laws of optical physics,which will inevitably cause this phenomenon. could you try to turn down the degree until the black fade away?"So I guess I'll chalk this up to inexperience on my end. Still, I'm docking 2 stars because it's not documented anywhere on the item page which focal lengths are supported, which can lead to some mislead some buyers. Also, it's not really feasible to tell if there is a slight amount of uneven brightness while taking the shot or previewing in camera. Thus, you can end up with a bunch of bad shots that you wouldn't know about until you get back to a monitor.

Specs say 8.6 stops, but actual measurement says 7 stops - One stop adding filter to lens, set to Min. mark; 6 additional stops from Min. to Max. marks = 7 stops total.The 10 markings are not linear, can't be used to determine actual density. No hard stops at either end.This is a Nano B-series filter, and is well made.