Filter stacking on Tokina 11-16

A couple questions.

1.) Stacking B+W 6-stop ND filter and B+W Slim CPL = Vignetting? I would assume so at 11mm.

2.) Is the 6-stop going to be too dark to see through the viewfinder to compose? If so I have a problem since I have to stack ND then CPL then compose then turn the CPL to get correct polarization of water/sky.

Wish I had thought of these things earlier so I would have bought all square filters instead of screw on. Maybe I am wrong and it won't vignette and you can compose through a ND + CPL?

1.) It'll probably be close at the widest end (11mm, 12mm) of the zoom. If you already have the filters, give it a try.

2.) It depends on the amount of available light at the time. However, since your camera has Live View, you'll be able to attach both filters, then use Live View to compose, meter, and focus right through the filter stack. Also, remember that the polarizer will add some additional light loss to the mix, depending on how much you have dialed in. I do this myself when shooting with the Singh-Ray Vari-N-Duo or with the B+W 10-stop ND...the beauty of having Live View.

I've been through this exact scenario and you can assume vignetting exactly as Argyle mentioned with two stacked filters. Assuming you are not rushed by a sunset and are shooting a waterfall or other static landscape, you may also want to spec the "ideal" frame you want to capture before mounting filters. That is, mount your camera on your tripod; compose your scene as you usually would allowing for good margins in the frame; use your autofocus to determine various focal points in the scene and note the exact distances; then take a couple of test shots at a few focal lengths--maybe 12, 14, and 16mm. You can then turn off your autofocus, mount filters, meter the scene, manually focus using the lens guide or live view, and take a fair range of shots at the focal lengths and distance settings you have already spec'd out. It's just a process and you'll probably just have to choose between a light crop on the widest shot, a tighter composition on the long end, or the perfect frame at 13mm, or so..

I haven't bought anything but the B+W Slim CPL so I am not too far invested yet. I would still want to use that CPL over square ones for sunrise/sunset anyway as it will be much easier to work with than holders.

I am not having much luck finding square ND filters though. All the ND filters I am finding are graduated. Anyone have a link to where I could shop for a square ND? Do they even make 6 or 10 stop square ND's? I found some HiTech ones but they only go up to 1.2, which I assume is 4 stops light reduction.

Would this be a recommended square polarizer? http://www.bhphotovide​o.com …ular_Polarizer_​Glass.html

As far as a holder, is this the Lee kit everyone recommends? http://www.2filter.com​/Leefilters/LeeFilters​4x4.html
Reading further into this, people say you can get light leakage with square filters. That doesn't sound fun.

So I would just need the Foundation Kit and Wide Angle adapter ring? Is that holder + adapter designed to allow two filters (polarizer, ND) to stack without vignetting?

Couple of things. First, the B+W slim CPL filter does not have front threads, so you won't be able to attach the holder to this particular filter. The Hoya slim CPL does have front threads, but that brings in another problem. Namely, attaching the wide angle adapter ring to the filter. The Lee WA ring is designed to sit about 3-4mm further back on the lens barrel in order to "pull" the holder closer to avoid vignetting. I'll occasionally attach my Lee holder and WA ring to my B+W F-Pro polarizer (non-slim) but this arrangement makes it (1) difficult to adjust the polarizer and (2) a little tricky when trying to separate the two. The only way to adjust the CPL in this set-up would be to rotate the entire holder until you achieve the desired amount of polarization. My guess would be that if you could attach the WA holder to a slim CPL, the 3-4mm recess in the WA holder would cover the adjusting ring on the CPL, making it almost impossible to attach/separate the two.

As I mentioned earlier, since you already have screw-on filters (6-stop ND and CPL), simply mount the ND first, then add the CPL...use Live View to focus and meter provided you have somewhat decent light. LV will "see" through the entire filter stack. Another option is to sell off the B+W slim filter and pick up the F-Pro (non-slim) version. This filter will let you work in tandem with a filter holder and square/rectangular filters.

Another option, albeit more expensive, is to pick up a Lee or B+W 105mm CPL that attaches to the front of the holder via a mounting ring.

Not sure if this helps you at all, but when I have the B+W F-Pro on my 17-40L lens, coupled with the Lee WA ring and holder with two slots, I'll get some obvious vignetting at 17mm. The vignetting is minimal at 19mm, and completely gone by 20mm. This is on a FF camera (5D2), so maybe the focal lengths may give you an idea as to what to expect on your crop and 11-16 lens.