How good is the auto exposure at getting it right on very bright sunny days.  Should I still pop an ND filter on?  If it's best that I do, what value is best?

Personally I use a variable ND filter, set the shutter speed to the correct 180 degree value, then twiddle the filter till the exposure looks ok.

This is a question I am exploring too. I have a PolarPro 6-filter set and I have tried to use it myself using manual ISO and shutter settings. So far, I have tended to set them badly so my footage looks too dark most of the time, or has huge contrast differences between well-lit and underlit areas. I have tried to keep ISO at 400 and shutter speed at 1/60 (Filming at 1080p 30fps, High Quality mode enabled). I think I'll have to still practice more  to find the proper ISO values and discover the balance between image brightness, smooth natural looking motion blur and avoiding getting grainy footage.

As far as the ND filters go, I remember reading these kind of rough approximations somewhere:

ND4 - indoors, at dusk outdoors
ND8 - cloudy, grayish day outside
ND16 - half-cloudy day outside
ND32 - bright shiny day outside
ND64 - very bright shiny days and conditions (for instance, when shooting at snowy, bright locations on a sunny day or near areas of water that reflect the sunlight)

Of course, these are rough approximations and depend on the lighting conditions available.

HGDC84 Posted at 6-4 06:42
This is a question I am exploring too. I have a PolarPro 6-filter set and I have tried to use it myself using manual ISO and shutter settings. So far, I have tended to set them badly so my footage looks too dark most of the time, or has huge contrast differences between well-lit and underlit areas. I have tried to keep ISO at 400 and shutter speed at 1/60 (Filming at 1080p 30fps, High Quality mode enabled). I think I'll have to still practice more  to find the proper ISO values and discover the balance between image brightness, smooth natural looking motion blur and avoiding getting grainy footage.

As far as the ND filters go, I remember reading these kind of rough approximations somewhere:

I'm curious why you're keeping ISO at 400 instead of 100?

I was meaning when using the P2 in full auto mode.   Not using any manual settings at all.  Would I benefit from using an ND filter on very bright sunlight days or can the auto setting cope ok?

John Walker Posted at 6-4 09:19
I was meaning when using the P2 in full auto mode.   Not using any manual settings at all.  Would I benefit from using an ND filter on very bright sunlight days or can the auto setting cope ok?

You will, you’ll notice difference in greens and sky and although you could still recover in post you’ll find something like 16 ND is adequate.

John Walker Posted at 6-4 09:19
I was meaning when using the P2 in full auto mode.   Not using any manual settings at all.  Would I benefit from using an ND filter on very bright sunlight days or can the auto setting cope ok?

I think it comes down to the fact that a camera with a fixed aperture only has one way of setting exposure, and that is by changing the shutter speed.
The problem with this is that faster shutter speed while they can darken your image also reduce motion blur. This makes video look more stuttery rather than smooth.
So using nd filter makes a huge difference in the video not looking better.

(Being legally blind, I can't really discuss colors ^^)

Thanks for all your replies - very much appreciated.   I notice that some of my highlights get blown on sunny days and was hoping an ND filter might help but reading your replies it looks unlikely.  My main video is clips taken as I walk about so using the full auto is perfect for me.

ManaHime Posted at 6-4 08:40
I'm curious why you're keeping ISO at 400 instead of 100?

As far as I have understood, the higher the ISO, the less there needs to be light - but the grainier the image quality will be. Leaving ISO at 400 gives some light to it (at least in theory) yet doesn't introduce too much noise into the picture. In practice, even at ISO 400 the video seems to have been too dark, and I believe at ISO 100 the darkness would be even worse.

Though this might be just that I have miscalculated and used a wrong ND filter, and possibly need to try with another one or just leave it off altogether for that situation. I think I just need to try and practice until I get the hang of it - or see if leaving the ISO setting or shutter time to automatic works better for me.