Help buying, Dark ND filter. Cokin or Screw in?

[Hoppy110]

Iv just bought a set of ND2 ND4 ND8 and Graduated versions of those 3 for the cokin fitter holder P.

I do some video so its great to have proper drop in filters.

However I want to do some long exposures in the day time, mainly to get the smooth water effect on beaches etc.

Would ND16 (the highest ND I found for cokin) and possibly an ND8 on top of that be enough for a 1-3 second exposure in daylight?

Also I have read that when doing long exposures with a filter system like the cokin you can get some light leaks and light reflections. Does anyone have any experience with this system? I will buy the mini hood that encloses the filters a bit more to prevent some light leaking.

Want to know all the details so I can chose between buying an ND16 for cokin or a higher ND screw in filter and the step downs.

 

[carla marriott]

I have previously bought some screw in filters fairly cheaply but when you stack them for daylight long exposures you get a magenta hue to your photos. I personally prefer cokin now because of this problem.
Have taken 20 sec exposures, in daylight with Cokin sucessfully

 

[Hoppy110]

Awsome thanks, I think I will buy there Nd 16 now