The Firecrest filters do an amazing job of cutting light - and most importantly - drastically reducing IR and UV contamination. Used this on both a BMD URSA Mini 4k and a Pocket Cinema Camera for a wedding scene in a movie, and it's worth investing in a quality filter. Other filters I've looked at only target the visible spectrum, so you'd need to stack a UV and/or IR filter on top of that. This one combines everything, resulting in little to no haze and equally as little brown contamination.

used it couple of times and found ok

The ND filter I received had three bubbles in the glass (or coating) that caused blurring problems with my images. After waiting over 5 weeks for a replacement (back-ordered), I cancelled my replacement order and bought the same filter from another source. Same problem with on the second filter with the bubbles, plus the second one had a pinhole gap in the coating (which let's through too much light)and uneven coating near the edge of the filter.Two bad filters...I will never buy any Formatt-Hitech products again.

Just started dabbling in long exposure photography and this is my first ND filter. Used it with a Canon 24mm 2.8 IS USM lens mounted on a Canon 6D camera and it worked great. No color cast at all as far as i can tell. My only complaint is that I found it later at BH for MUCH less.

Just perfect and very very fast shipping

I have the 82mm version of this and use it with step-down rings for smaller lenses. This is the best and most convenient ND filter with more than 16 stops. It works very well and has only a small color cast (blue-ish), easily corrected for. I have not noticed any distortion or unevenness. The filter is very expensive, but I haven't found any other solution to give me that much near-neutral density. You can use welding glass (17 stops), but it forces you to black & white, as the green cast is too strong to be corrected. Stacking multiple ND filters usually degrades image quality too much.One minor issue with this filter is that the glass is held into the ring with a second ring that screws into the back of the larger one. That secondary ring tends to come lose, which is why others report it falling apart and may be a reason for light leaks, if not screwed tight (easily done). One other note to people complaining about light leaks is that you need to completely close your view finder on DSLR cameras for long exposures, it is a source of light during the day.The image shown is a continuous 20-minute exposure with that 16 stop filter of the moon, which does not show any clipped highlights. Only possible with a filter like this.