So I bought a bunch of new filters.

A circular polarizer.

A variable neutral density.

A 2-stop graduated neutral density.

All are 77mm in size. I would always keep a 35mm kit. Been keeping in touch with Nikon D600 rumours. Sorry no Canon for me. Nikon CLS is just magical.

Then I looked at step up rings.

Ouch. I'm going to need a 52-77mm, a 58-77mm. For sure.

But how do you guys feel about step ups from 37mm and 46mm? Should I get them to step up to 52mm, or 58mm? Cause 37-77mm and 46-77mm doesn't exist.

I used step up for my Panasonic pancakes. They work fine, the only problem was that they look weird small lens with over sized filter on it. I think I was using a 58mm to 46mm. eventually I just got the 46mm ones, but I don't use as many filters are you (pretty much just ND + SPL only, and nice that the 2 pancakes I own are the same size)- so it wasn't too bad.

I think, apart from looking a bit funny, all that weight on the 20mm's focus mechanism might be a bad idea in the long run. I have no evidence for saying that of course :) but I felt I might be pushing it with a 52mm. I wouldn't be so concerned if it was the 14mm lens as that's got any moving parts externally, likewise with the 45mm.

I'm rarely going to leave a filter on for a long time.

The ND is only used when I want to use longer shutter times in daylight, or use a lens wide open.

The polarizer is only used when I want certain effects from the sky and vegetation.

The grad is used the least. Landscapes where the highlight will be blown.

The choice of stepping to 52mm vs. stepping to 58mm boils down to which zooms I would keep I guess. Good thing step up rings are cheap. Most of them are $2 including shipping.

Kind of leaning toward 52mm.

Yeah- that 20mm focusing. I stuck a thick diopter on there once, the motor whirred to a stop.