I've been looking at the Sony Gradient Map, but it seems to generate a gradient from dark to light over the whole picture evenly. What I'm looking for is a way to darken a bright sky without darkening the landscape beneath it - the same thing you'd get using a gradient filter in front of the camera lens.

Just add a color gradient generated media clip on a track above the video clip and set a few control points (the two lowest points to Alpha 0% to make them transparent) to create a grad lens filter effect.

That sounds like what I need to do. How exactly would you set this up?

OK, now I see. You can make pretty much any gradient filter you want as an overlay. This is way cool!

Can anyone point me to some nice gradient filter presets?

Now THIS is interesting!

We could knock up a range of NDs and TABACS, Rosies . . could even do multiple angular and curvy things using Bezier!

Tell you what Laurence .. go look at one of the Filter providers and see what takes your fancy?

. . circular Pola is a bit of problem though! . . .

Grazie

. . circular Pola is a bit of problem though! . . .

Just use the Vegas CP plug-in.

It uses a worm hole to go back in time and put a circular polarizer on your lens.

:O)

I have been using polarizers since the early 70s, they really can do a lot of totally very different great things.

Note though that there is a big practical difference between a $50 Tiffen CP and a $250-300 B+W CP.

I was a bit surprised that the difference was visible even to the naked eye, and even more surprised that there was a difference when shooting miniDV (with a Canon XL1).

The B+W is a lot thinner than the Tiffen, this adds significantly to the manufacturing cost and is one of the major factors in increasing the optical quality.

Main use for me have been to increase saturation in sunny outdoor scenes. 2nd as a free extra ND filter at other times.

Very occasionally I also used them to remove the reflections that most people pull out polarizers for, but they don't always work for that.

Coursie, you ole wag you! . .Oh yes, my Pola? Wouldn't l;eave hoime without it. . . BLUE skies, try it with a graded TABAC - to good!

Grazie

i like the jim beam spots where they use gradients as an effect, like a worn out old film look (oranges and little yellows over images). i can accomplish this simply by making the layer 'add' with a gradient 3 tone color scheme, and things can look pretty interesting.

If you just want to darken the sky and assuming your sky is all blue use a Chroma Key FX to generate an garbage matte, fiddle with the matte and the compositing mode and you can make JUST the sky darker or even replace your clear blue sky with storm clouds. This is much more effective that a grad filter which cannot differentiate between sky and ground which makes them pretty easy to pick when they're used unless you have a flat horizon.

Now the thing you should know, none of these tricks in post are anywhere near as good as using real filters in front of the lens.
DV and even film has a limited latitude, using filters in front of the lens lets you control the contrast of a scene so part of it isn't scrunched by the limited latitude of the recording medium.

Bob.

You could use the bezier maskto cut off the mask according to what's in the image.

The Color Corrector (Secondary) is like the Chroma Key and Color Corrector filter combined into one.

You can mask out just the blue of the sky and darken it. Lower gain to darken things. You can play around with the saturation slider... setting saturation equal to gain will keep "saturation" the same (the Color corrector's saturation control is really a chroma control, and the gain control a luma control). Anyways, making both settings the same will keep saturation the same.

That sounds like what I need to learn. Are there any good tutorials or preset collections for the secondary color corrector?