Although many lens filters were pretty much eradicated by the advent of digital photography, there are two which still hold a lot of value that can’t really be accurately replicated in Photoshop. Those are polarizers and neutral density filters. You can try, but you’ll never get it looking exactly like the real thing.
Recently, I’ve been trying out Haida’s M10 filter system, along with their circular polarizer, 6-stop M10 drop-in ND filter and the 100x100mm square 10-stop Red Diamond ND filter. The weather’s been kind of crappy here in Scotland lately, but I did get out to give them a try and do some slightly more objective tests, too. Here’s what I found out and what I think.