Filter Holder size question

[jumpinminnow]

In making my transition a couple of month ago to new equiment, I expanded my focal range down to 12mm where previously it was 17mm. I used a Cokin P holder with my GNDs but I now get vignetting at anything below 15mm.

I'm using the Tokina 12-24 f/4 and am considering getting a HiTech 4" holder. I was just wondering if anyone had any thoughts on this and is this what I need to do to continue using GNDs? I'm fully capable of blending but like to get the exposures close inthe camera if possible.

[jumpinminnow]

No takers? Surely someone's been down this road...

[venchka]

Are your GNDs 4"? You don't say what the diameter of the lens is. I'm guessing you need filters considerably larger than the lens barrel.

Good luck.

[jumpinminnow]

The thread diameter is 77mm, but I don't think that's really the vignetting issue compared to how wide the field of view (12mm) is. My old wideangle was a 17-35mm with the same 77mm threads and I never had an issue. I am using a Nikon D300 and not a full frame sensor.

To be clear I'm not opposed to getting new filters if that's what it takes. I'm just looking for some confirmation that 4x4, 4x5 or 4x6 filters should do the job. I've also read where someone Dremelled off the outside two slots of his P series holder to prevent vignetting, but it didn't say how wide he was shooting.