Hope everyone had a good weekend!
Thank you for commenting Worst Case.
The liquid in the glass is the same color as the liquid in the bottle. It was matched before the shoot. As cameraclicker mentioned the liquid looks different because it is being displaced by the cube at the bottom of the glass, which did indeed cause the splash. There are spots of the liquid that actually do match. The differing colors are simply being caused by the back lighting in the liquid.
The scene is backlit (among a lot of other lighting) for separation purposes and also to give the liquid its glow. Otherwise the liquid would look unacceptably dark! There is a small reflector/diffuser, just smaller than the glass, with some slots cut in it behind the glass. The slots are to let some of the negative light of the black BG to come through in the liquid and the solid glass base of the glass. Without this the base of the glass would photograph as solid black. As an example you can see a solid black piece in the base of the glass. This corresponds to a slot in the reflector/diffuser behind the glass. To portray a glossy surface the gamut needs to run from solid black in areas to solid white in areas and tones in between. Otherwise it photographs as matte. There is also a reflector behind the bottle with no holes cut for a more even backlighting effect.
nesgran, I like to get as much as I can in one shot but this is a composite. It’s the only way really unless you want to clean up the set everytime between splashes until you get what you want. And I never get what I want the first time! And you can’t move things around once you get the lighting set. It is very precise and sometimes the lighting can change drastically with just a small movement of either the subject or light. But I certainly want as few shots as possible if compositing.
I don’t use a DoF calculator (admittedly I probably should!). Shot fairly well stopped down (f/16) needed the ISO value. I might have gotten away with opening up a bit but certainly everything in the shot needed to be in good focus. I didn’t fiddle with the settings too much as long as I could get the DoF/light/duration I needed and f/16 was an arbitrary decision. I always shoot tethered in the studio and just eye-ball the DoF! I don’t consider ISO 800 a big deal at all for this kind of work although its probably unheard of in studio portraiture I suppose.