Something like that. Or aluminium foil we get to wrap food...For your shooting distance you would probably need to have some reflective material on the bottle where it is not facing the shot. You don't want to waste the light going out from there... That is where the plastic bag fails. It is fine for closer home shots. And you will need to dial up the flash exposure compensation too...So I spent the day learning about high sync shutter and it is really cool. I know I will easily be able to shoot at 1/2000th of a second using the 430ex ii and my 60d, but I'm not 100% sure what I will do with the bouncing of the light. I think what I am going to do is make a home made diffuser to mount over the speedlight so I have the light, but it is not as powerful.Home made diffuser? Simple! A translucent white plastic bag and a rubber-band! That it! And the best part is that your diffuser height and even the shape is variable
What I have right now is a plastic water bottle with the top cut off, then I have it fitted around the top of my flash. It looks SUPER classy, but then I'm going to put in "ribbons" of translucent white filler paper. The kind you would put in a gift. And that should glow evenly and give the desired effect of sending a soft white light in multiple directions, while at the same time, not absorbing all the light to the point to where it is not even worth using flash. That's my plan in the mean time.
But I did think about a plastic bag too... but I figure that would look even worse.
So tin foil? facing the rear (towards me) so that light will bounce forward as well.
That must be my Texas roots coming out. I'm nt sure why we call aluminum foil tin foil... but we do.