I bought a set of six square (plastic Cokin P knock-off) ND filters from a Chinese eBay seller last July. Never tested 'em until today. I popped in the graduated ND8 (3 stop), the darkest grad in the set. The set also came with the plastic filter holder and a large set of metal adapter rings to fit many lens filter thread sizes.

$17US, shipped, for the whole package.

I had to do a -1.5 stop exposure comp in the computer. It seems that the camera gets a bit confused by the scene and overexposes. I'll set in-camera next time.

This was shot with my Tokina 100mm f/2.8 macro lens, probably the sharpest one I own. When zoomed to 1:1 on screen, with and without the filter in place, there seems to be little if any apparent resolution loss, despite the cheesy plastic filter and the scratch I already made down the center of the filter by being a