I would like to use a 52mm graduated neutral density filter with the 300mm lens and I was talking to a guy at B&H and he said by using a graduated neutral density filter in the filter holder, I wouldn't get the same results as if I were using it on a lens that has screw in threads on the front of the lens. Do you think this is true ?
I haven't used one (I do have the drop-in CPL, however), but I think he was probably saying this because you can't adjust it once it's inside the lens. Unlike the drop-in CPL that has a brilliant thumbwheel, the holder is just that - you insert the cut gelatin filter then insert it into the lens. You won't be able to rotate it once it goes in nor can you raise or lower it to adjust the horizon level. The line will be in the center and you won't be able to adjust it unless you take it out and rotate it and then put it back in the lens. Additionally unlike the Drop-In Filter Holder for 52mm Screw-In Filters
, the gelatin has to be cut in an octagonal shape which will limit the number of ways your can rotate it. I'm not even sure if you can buy graduated ND gelatin, so I think you'd have to buy the screw in holder and a thin 52mm ND grad to go with it.
Unless you have a very specific purpose, it's a costly way to limit yourself to shooting with a dead center horizon. The filter holder is best suited to a plain ND (i.e. not graduated) filters to slow shutter speeds to achieve blurs or shoot wide open in extremely bright conditions. Art Morris does this with a 3-stop ND using that drop in holder to create his blurs.
If you want to do it with the plain ND gelatin, I'd recommend the good stuff - Kodak Wratten Gelatin
. It's expensive but it's the best