Hitech Filters,which one & what mount

[plloydie]

I'm considering getting a Hitech Grad filter for landscape shots I'll be using it with a Sigma 10-20mm lens and maybe other lenses should the need arise, but, I have no experience of using filters, so what filter would i need to start, what size and what to mount the filter on, also would i get vignetting at the widest setting with the Sigma?
Thanks

 

[Peter10d]

The Hitech 0.6 grad soft, will cover you for most landscape shots.
I had issues with the 85mm filters at the wide end on a Canon 10-22. 10 and 11mm being noticeable.
Having tried various filters holders, I ended up using blue tac to hold them on, which worked well for me. Since switched to Lee with no issues.