Barry, I noticed on another board you mentioned this for the DVX100a:

1/8 = 3 f-stops (1=1/2 the light, 2=1/4, 3=1/8) and 1/64 = 6 f-stops.
1/8 = ND.9
The 1/64 is the same as using two ND .9's.
I don't think you'll need a stronger ND, the existing 1/64th will turn an f/16 scene into f/2. If you do decide to get an external ND, I'd recommend a .6, not a .9, because you've already got two .9's built into the camera.

So I bought a .6 for my dvx per your recommendation, and on one shoot, the DP was happy I had it.

But now for the Sony HDV...

The ND1 and ND2 built in filters are 1/6 and 1/32. What would you recommend for an external ND for this camera?

- Shannon W. Rawls

The .6 may work well, but I'd be inclined to recommend a stronger filter, probably a .9.

Reason being, the Z1 needs to keep the iris more open than other cameras do, due to the tiny pixel size of the HD chip. That tiny pixel size makes the camera more prone to diffraction issues with smaller apertures. The tinier the pixels, the more out-of-focus an image will look when the iris is stopped down too far. There's a great article on diffraction here on DVInfo.net.

Sony even included a menu option that can limit how small the iris can go, which will prevent diffraction: I think the settings are 5.6 or 8. Obviously f/8, with a 1/32 ND, may not be enough to compensate for bright sunlight conditions. However, it may be -- because the Z1 isn't quite as light-sensitive, perhaps the ND is enough.

A 1/32 is about a five-stop ND filter. A .9 is a three-stop filter. So combined you'd have 8 stops.

But before buying anything, try your 2-stop filter in combination with the 1/32 in-camera filter, on a sunny bright day (or in snowy conditions). If you can keep the iris in the f/4 to f/5.6 range with those ND choices, and avoid blown-out highlights, you don't need any stronger filter. If the camera's recommending f/11 under those conditions, I'd recommend getting the stronger ND filter, at least a .9 and maybe even a 1.2.

cool thanks. I'll just buy the .9 to be safe. the .6 i have is a screw-on type 72mm. I need a 4x4 type for the z1. so da heck with it, i'll just find a .9 to add in the event i need to block even more light. thanks BG!

- Shannon W. Rawls