1.) Does any one know what the ND filter built into the 16x auto lens equates to in filter terms? ND1, ND2...etc

2.) Does anyone know a good website, or have a little time to explain the zebras. I understand well what they are used for and the theoretical stuff behind them. Just not familiar with then on XL1s yet and what setting is the best to use. 80, 85, 90 etc? And with those settings, what is the effect they can give to finished?

Best not to believe what you read about the in-built NDs absorbtion, but to actually test it out. It's so simple to do. Tripod, constant light source, auto reading and switch to manual. You'll now have a readout of the shutter speed and aperture.

Switch in the ND and follow the same proceedure. If the shutter speed remains unaltered and the camera opens up three stops then the filter is an ND8.

As regards the zebras, remember that they are only a guide. It's a matter of getting to know the damage to your footage caused by over-exposure that relates to the zebra setting you're using. If I were you I'd choose a setting (90, say) and stick with it. Learn the effect, see how much the camera tolerates in auto and work with and around the experience you'll accumulate.

tom.

To build on what Tom said, experimentation is you best way to learn. I use one level of Zebra when I shoot hawks in flight against a blue sky and another level for Caucasian skin against a dark background. You can just set it and run with it in all conditions and lighting situations.

Tom,

Quite often, ND filters are not expressed in terms of "attenuation factor", which corresponds with yr explanation (ND8=8 times attenuation= 2^3 = 3 stops), but in terms of "optical density" (OD) which relates better to the human visual system. ND 8 would be "very dark" in this logarithmic specification method. See http://www.schneideroptics.com/filters/filters_for_motion_picture_&_broadcast_television/neutral_density_filters/