This has been a bad year for rectangular/drop in filters. Cokin had issues earlier this year, and stopped production for a while, as a result sourcing a 4″ filter holder from either Cokin or Lee has been a challenge. Sourcing the filters hasn’t been any easier.

In the mean time while trying to get filters, I’ve been playing with my Cokin Z-pro holder, trying to find the right orientations for each of my lenses while trying to get as many filter slots available as possible.

What I’ve found is that there are 3 possible orientations you can use without having to take the filter holder apart. They will give you 1, 2, and 3 available slots without having to take the holder apart. (Click the images below to enlarge.)

1 Filter Slot	The filter holder is reversed so that the mounting ring is in the closest filter slot on the front (3-slot) side with the threads pointing away from base plate. Just about any wide or ultra-wide angle lens (for FX and crop DSLRS at least) should not show any vignetting with this configuration.
2 Filter Slots	The adapter ring is inserted in the “rear” most filter slot in the 3-slot side, and then the whole ring and holder assembly is screwed into the lens’s filter threads.Though this is most difficult method to setup, it doesn’t vignette on the widest lens I’ve tested it on (a Canon EF-S 10-22mm f/3.5-4.5 USM) and you get 2 useable filter slots instead of 1.
3 Filter Slots	The normal mounting, with the adapter ring slotted in the single rear slot and the filters in the front. This shouldn’t vignette on anything longer than 24mm.

While they’re kind of obvious once you see them, I spent a good 30 minutes trying different sized “stacks” of front filters trying to find the right combination that didn’t vignette on my EF-S 10-22. It turns out that the biggest problem with that lens is the thickness of the “baseplate” that holds everything together; take that out of the equation and you can do 2 filters without any vignetting.

And for those who are curious, I went with the Z-Pro holder and the 4″ filters, even though they’re more expensive than the P system’s 80mm filters. The answer is simple, I’ve used P series filters on my ultra-wide and the holders has always vignetted at the widest focal lengths. As a result, I either can’t shoot as wide as I’d like, or I end up holding the filter instead of using the holder.

The X-pro (4″) filters, are big enough that even on the EF-S 10-22 at 10mm I can get 2 filters of effects without having to worry about vignetting. Besides, if you need/want to save a couple of bucks on P filters for occasional use on longer lenses, there’s always the Cokin P to Z-Pro Adapter^{(Affiliate Link)} .