Originally posted by dkittle
I'm also toiling with a screwing Tiffen vs. Cokin. The problem is, my most used lens for landscapes, sun and sky is my Pentax 12-24mm. Cokin doesn't seem to support a lens that wide. Tiffen would work better, even though I'll likely have to remove the UV filter to avoid vignetting.
I use a Tiffen 77mm ND 2 stop graduated neutral density filter. For my needs, it actually works quite well. I know that you can't adjust the position of the transition up and down, but it doesn't really seem to be a problem. I usually have the horizon about 1/3 of the distance from the top of the frame (or less). The natural variations in the landscape below the horizon seem to always mask the filter transition. If the horizon is
below the middle of the frame, then I won't use it. But I don't take very many shots that are more than 50% sky. I wouldn't use it if the transition fell over an object with a smooth, even surface (like smooth water or desert sand). Be sure to use the DOF preview to see what the shot will look like.
The Tiffen filter will cause vignetting on the Pentax DA 12-24mm at 12mm, even if it is the only filter. It seems ok from about 14mm on. And it works fine with the Pentax DA 14mm f/2.8. (It also works fine with my Nikkor 12-24mm f/4 DX lens, even at 12mm. But this is probably not of much interest in a Pentax forum.)
I was considering a Cokin system, but it seemed like a lot of stuff to carry around (filter holder, adapter rings, filters, and Cokin lens hoods). The Coken Grad ND filters don't have the best reputation for quality. The good Singh-ray filters are quite expensive. And I was concerned with compatibility with a 12-24 ultra-wide. According to the Cokin Web site, I would need to get a "Z" system to cover a 12-24mm, and I certainly didn't want to go there.
One idea is to skip the filter holders, and simply get a good grad ND filter (e.g., Singh-ray) and
hand hold it in front of a the lens (with the camera on a tripod). This seems like a reasonable solution, and I might give it a try sometime. If you've ever read any Tim Fitzharris books, what he does is just tape the filter to the lens with duck tape!