What size nd filter

[Tbant]

Hi I have got a tamron 24-70 2.8 that I want to get some nd filters for. Has anyone got any idea what system would be best? Have looked at Cokin P, Z, Hitech 85mm and other 100mm filters. The lens has an 82mn thread so I am wondering if I can get away with the smaller size systems with out vignetting when shooting wide?
Any one got any experience of the P size wideangle holder on a similar size lens?
Also is the Hitech 85mm holder the same as the Cokin P holder or is it a little larger as I see some sites saying its compatible with the P filters.
Moneys tight at the moment so whilst I am experimenting I don't want to spend more than I really need to, so any pointer greatly recived.

 

[RichardTaylor]

I shoot with a 24-105 lens (77mm filter thread) on a full frame camera (usually with a skylight filter on the lens as well (I don't want the lens splashed with sea water) and the cokin P filters vignette at the wide end. I just live with it.

Are you using a full frame camera?

 

[Tbant]

Hi thanks for the reply, yes I am using a fx camera.