Is the Cokin system a good choice for ND grad filters? Or are they the only option? (Aside from the more expensive Lee and Singh-Ray). Am I right to assume you can't get a traditional round screw-on ND grad filter? The Cokin is probably a good system to get into anyway by the looks of things. Are Lee and Singh-Ray filters compatible with the Cokin system? Any pros/cons of the Cokin vs. the more expensive system?
Welly, circular ND grads exist but they're rubbish for more advanced users. Why? Well the transistion zone is fixed on the filter and you have to frame your image in a certain way. The Cokin system is a large rectangular piece of glass that can slide up and down in its holder, so you can place the transistion point of the grad where you please and compose regardless of the filter.
Cokin is cheap, cheerful, and works. Yes it lacks the top IQ of more expensive filter brands, but that doesn't justify paying multiples more from a financial sense.
Lee and Singh-Ray filters do use the P and the Z series holder made by Cokin.
Alex, I'd also recommend a tabacoo filter.
I beg to differ Jake. You can create the "tobacco" effect in PP. My advice is inspired by a cigarette box: "Don't do it. Tobacco kills".