If you buy any filters at all make sure you invest some money into what you're purchasing. If you're using expensive or quality made lenses you're not going to use cheap filters. That's the equivalent of purchasing a Ferrari and putting on seat covers you purchased from Autozone. You just don't do it. Or you do because you don't give any fucks and don't want mustard on your Ferrari leather.
Here's the thing: You paid good solid money by purchasing a nice lens because you wanted the utmost clarity you could afford (we're talking about wide angle lenses in this scenario.) Why diffuse that clarity with cheap filters?
I carry 3 filters in my bag. I carry a polarizer (which I admit to being cheap) and I'm ashamed of it. I carry a Lee Soft Neutral grad filter, and I carry a B+W 10 stop filter. Those are my essentials for now. The polarizer is from Calumet photo. They said it was a B+W polarizer with their name attached to it... So far, it hasn't been awful, but I have to imagine it's not the best.
Below is a photo from Saganashkee Slough out in the Palos area of Cook County Forest Preserve. It's my photography oasis for fucking shit up. Basically, it's where I go to test out my filters, compositions, colors, and whatever else I decide to experiment on. I used a 10 stop filter. A 10 stop filter looks like welding glass. If you don't know what welding glass is then let me explain. It's a high coated piece of glass that looks like it's limo tinted. The idea is that it stops light from penetrating to the sensor of your camera so that it almost bleeds into the camera instead of pouring in.
See the clouds below, and how they are silky smooth and kind of ghostly in their movement? That's the effect of a long exposure with a ten stop filter. The longer you expose the greater the movement. It's almost like a cotton candy effect.
There is a science behind long exposures, but what I've found is that by experimenting with your focal lengths, filters, and camera settings you get the best idea of what to expect. See, the equation using all those variables will produce an idea, but it won't paint the entire picture. The biggest unsolved variable remains to be the natural light, time of day, and atmosphere. That's why I've found that by messing around with various long exposures on different settings have given me the best results.
I'll go over the other two filters in separate blog posts soon.