Alright I'm working with Illustrator and I want to have the hex code for a color that I've lowered the opacity on. When I try to get it from the color picker it only gives me the hex of the 100% opaque color, whereas I want the same color's hex when it has less opacity applied to it. How to obtain it?
There's a proper way, and there's an easy way:
1) The proper way: You can flatten transparencies. Make sure to save to a new file before doing this as it will "break apart" your illustration, making it harder to edit after.
2) The easy way: Just screenshot a zone of the color with opacity and then color-pick the resulting image. ("CMD + SHIFT + 4" if you're on a Mac for selective screenshotting) Or as Cai noted: If you use "CMD+CTRL+SHIFT+4", it doesn't make even make a file on your desktop, it keeps the image in your clipboard, and then you can paste it into your illustrator directly while keeping your desktop clutter-free.
Note: I'm guessing some people will say you should never screenshot colors for reference, as saving to PNG probably alters the colors very very slightly, but I've never had a problem and find that to be easier than to flatten.
If you happen to have Illustrator and Photoshop open at the same time you can just use Photoshop's color picker. Just use the eye-dropper to click anywhere inside your Photoshop canvas and drag your cursor over to the the area you want to sample in Illustrator (or anywhere else for that matter).
There are also countless other stand-alone color pickers you can use (apps, extensions etc.)