How do I evaluate Saturation with scopes?
 

Is saturation strictly subjective or can I use scopes to adjust saturation? If so, how?

You need to look at an image with a vectorscope. The traditional vectorscope has small square targets that indicate where the 7 primary and secondary colors fall. For 601 images, the color targets represent 80% saturation. For 709 images, the targets should include 100% for Blue, red, cyan, and yellow. If you can't look at a color bar pattern with your vectorscope, keep in mind that the concentric circles on the vectorscope represent saturation levels.

Thanks for responding Biil. Sometimes one color, maybe green, looks too saturated, but the vector doesn't really extend out past the markers. Is adjusting saturation mostly done by eye, except when it's 'out of bounds on the scope'?

I've been learning some basic color correction and understanding proper Saturation seems to be alluding me.

The way I guage color balance, like one color is too strong, is to look at the center of the vectorscope. The big white "blob" should be pretty much centered on the central dot. This is an indication of the color balance of the shadows. To get an idea of the color balance in the highlights, ie the whites, look at the "RGB Parade". The peaks of each channel of RGB should be at about the same level. Adjust each channel independently to balance these out. Note: this ONLY works with white.

With RGB parade in a waveform you can also spot possible oversaturation. Look for any one of the channels approaching or exceeding 100 IRE.