akeigher wrote:I want to buy a few graduated ND filters - at least a .3 and .6, maybe a .9 too depending on cost.
However, I am really at lost as to which filter to look at.
These filters would be for lenses with a 77mm thread.
I read somewhere that if i get square glass filters I to be able to adjust where the gradient occurs... but i have no clue which filters or sizes, etc.
please help.
thanks
You can use a Cokin P sized holder and any filter that fits it ( I think they're 82 or 85mm). Definitely use square filters. Round ND's are really only useful to drop the EV of the entire image. As you stated it is desirable to move the point where the transition is placed with out changing the way you have the image framed. Squares will slide up and down or side to side depending on how the holder is turned. The Cokin holder is two piece, a metal ring that threads on the front of the lens (they come in assorted diameters.), and a plastic holder that slips over the top of that. The holder spins with enough resistance to hold it where you align it. You might want to start with a selection of Cokin resin filters and see which you use/like most then buy glass (more expensive) filters as the Cokins get worn. Besides density, ND's come in hard and soft transition, as well as partial (usually 1/2 &1/2) gradation and full (top to bottom) gradation. Finally be aware that some holders, the Cokin included can cause vignetting on wide and ultra wide angle lenses. I use them on an 18mm Nikkor and sometiimes have a problem with this. My personal stash is a run of Cokin's, p120 - p121f.
I get mine from
B&H or
AdoramaHope this is helpful. There are a couple of other threads that address ND grads here, if you have time to search them out.