Should I choose screw-in or square ND filters for landscape photography?

I enjoy DIY projects.

A good quality square filter holder can be used with your home-grown versions as well as both round and square store-bought filters. You can use gelatin, glass, or plastic. That way you can also buy filters intended for other equipment so long as they are larger in diameter than your lens. You don't even have to cover the whole lens for some effects that begin or end at the horizon or other straight-line in your shot.

Try building a tiny glass "tank" to fit inside the filter holder that you can fill with food dyes mixed with water (or alcohol on winter days). The dyes can be dropped into the tank and used before and after becoming evenly mixed for a myriad of unique effects.

A small removable liquid filter tank is made with two squares of glass sealed with silicone sealer and thickness spacer of plastic tubing in the shape of a "U." Leave the top of the tank open to fill with an eye-dropper and empty by removing the tank and spilling out the liquid.

Hand-held shots can be ruled-out and a good tripod is necessary for this technique; but, you should be using one with a shutter release for good landscapes anyway.

The formula for re-creating certain hues is counting 1 drop = 1/20 millilitre. When you know the volume of the tank, you can recreate your favourite colours to-go. Keep notes

Is this a hassle? YES

Is this fun? YES

Will you regret this? NEVER