Will putting the ND filter on, open the iris more so as to increase the contrast range for light?

For all practical purposes, the only thing that opening the aperature will do to compensate for inserting a ND filter is decrease the depth of field.

I had to hope and ask. Thanks you.

Mike, your comment is timely for me. I've had a brief discussion recently on the Yahoo VX2000 group about adding an ND filter when shooting in bright sunlight, to push the aperture down to f 4 - f 4.8, where the camera does its best work. Yesterday I shot an hour in mid-morning sunshine in an area I've covered on three prior occasions lately, without the additional filter. I reviewed the tape last night and liked the result, although I need to gather some more experience on manual exposure with the filter in place. I've read many times that reducing the dof in miniDV is very difficult so my question is, what do I give up/lose in shooting with the ND.6 in place. It's been suggested that any filter will soften the image somewhat, but assuming one is ok with the visual results from a sharpness perspective, what else should I be concerned about?

David Hurdon

You would need to measure for any sharpness diffences between a bare lens and using an external good quality filter. Internal filters, which the switched ND filters are even better.

I don't believe there is anything to be concerned about in any situation using the switched ND filters as long as you meet your exposure goals.

Externally, as long as you use multi-coated filters from the best suppliers, you will not have any problems except, maybe, from light hitting a surface and causing a bit of internal reflection. But with good multi-coated filters, that is rare.

Just keep them clean.

Why is f4 to f4.8 considered where the pd170 does its best work?

All lens designs have a point at which all the elements are optimized for maximum performance. Sharpness, chromatic aberations, field flatness, geometric distortion, and more are all broght as good as possible at a specific aperature. That is typically about 2 f-stops below the maximum aperature.