I have both F-line and M-line 5x4" Arca cameras, and am considering purchasing a n Arca compendium hood.

However, some of my lenses (or prospective lenses) are fairly large - around 112 mm. I have thought about buying a huge 127mm screw-on Polariser with appropriat e step-up rings for each lens.

However, if I want to use graduated neutral density filters, the Arca filter hol ders only accept 100mm filters, which will be too narrow. I know they make a "c arton" which accept 125mm gels, but they would be of no use for graduated filter s.

The only filter system I've seen which is probably big enough is the Sinar 125mm square system. However, I'm not sure how it would work with the Arca bellows a nd the screw-in polariser - I don't think there is a screw mount on the front of the Sinar holder.

I am also considereing mounting a graduated filter in something like an Arca Bel lows Frame (I can get filters made to measure), and clipping it into an addition al front standard in front of the lens. I could therefore use the rise of this standard to move the graduation, and could mount the Arca bellows to the front o f this standard. I'm not sure about vignetting with wide angle lenses.

Sorry about the length of this question. I'd appreciate any advice.