a filmmaker friend has an nd filter that you can twist and darkens and lightens. for variable densities.
it’s crazy!

useful for digi maybe?

also, I hadn’t heard this before, but apparently nd filters tighten the range between blown highlights and dark shadows?

Forgive my ignorance but are you sure its not a circular polarizer?

Filmers use variable ND filters. No, they are not circular polarizers.

Not sure how could a ND filter “tighten the range”. Unless it has some type of graduation.
The ones ive seen havent had graduation.

what does a circular polarizer do?

the film guy, guaranteed me that ND filters would prevent highlights and shadows from blowing out or being lost in black, and that’s why they’re use in the film biz.

i havent tried or anything.

Hmmmm. From what I understood from the filmers is that they use the NDs to be able to keep lower shutter speeds.

Polarizers are used to control reflections on glossy surfaces and darken the blue skies amongst other things.

you got it antton.

ND’s esp for shooting film cameras with slower shutter speeds, and now DSLR’s which act like film cameras (shooting at 1/50thish for 24p) you need those ND filters to get any acceptable aperture.

polarizers help with color contrast being killed during the daytime etc.

there’s this video that shows good examples of them, check it out http://www.youtube.com/watch?v=x7JEPVpgcEQ

Been using NDs for a few years, as others have said, they do nothing to ‘tighten the range’, they just cut light, that’s it.
I use em so I can shoot wide open (or near wide open) with flashes, even when there’s full sunlight (D700 base iso of 200 means that you’re at 1/320 f/14 or something otherwise).