Any thoughts on what the effects are of leaving my UV filter on the lens (hate to leave it unprotected) when using the WD58h? Does moving it out one filter width affect it's field of view? Could other filters (polarizing) be used behind it without adverse affects?

Thanks

Take it off, Rob. It serves no purpose back there. It also pushes the WD-58 slightly out of its calibrated range.

I've started off that way with the filter in the middle, but noticed that I was having manual focus problems. I'd focus then zoom in or out and the camera would be out of focus. The UV filter stays off now, when the WD58 is on.

Yup, take the UV off when you add the widie. A filter adds two surfaces, both of which can add to the flare and both of which can have dust and fingerprints (but not yours or mine, right?)

You may find that keeping the filter there vignettes the corners of the frame slightly, and pictures to memory card and opened in the PC will tell you if this is so. If your widie has enough covering power to rise above this, then go ahead - use NDs or polarizors between widie and zoom - there's no real harm done.

tom.