How good are the Z1 in-camera neutral density filters in comparison to a top of the line from B+W ? They look ok to me, but I don't have a good screw-on ND for comparison. After some negative experiences with my Sony VX2000 in-camera ND filters, I'm more inclined to buy B+W. Which do you use?

they're OK, but if you need exacting exposures, having quarter value glass is always better, which is one main reason for a mattebox if you're shooting outdoors.

That's an interesting question. What negative experience did you have with the VX-2000? I've always just used the internal ND's on my Z1. Douglas makes a good point about having more options with external filters.

But putting anything in front of the lens is another chance for dust and smudges to get into the picture, and I would think it also makes flare more likely when shooting towards a bright light.