This image to the left was taken with no fill light. The following image has fill light bounced back using a foam-board.
A picture tells a thousand words. There are many variables to produce an array of styles but "KISS" is the motto here.
Begin by setting up your props. I started this out as a quick tutorial, not bothering to clean the bottle. Wish I had cleaned it. These images are straight from camera, without any post processing of any kind. I so wanted to clean the bottle in Photoshop but C'est la vie.
It's a tutorial on lighting I gave myself 60 minutes to get my gear out, shoot and put it all away. I spent more time getting the website set for the tips and tricks section which followed the shoot.
Now Let's Talk Light Placement
For a long vertical light reflection you need a long vertical light source . I used foam-board (it's what I had handy). I would have used a cardboard box but none were handy. To use a cardboard box, line the inside of the box with white paper. Keep the flaps of the box to replicate the barn doors. A box would allow to placement of the flash inside it and give better control for an even intensity of light thru-out. Hey, I said I only had 60 minutes, no time to scavenge for boxes!
In my example, the main light or key-light is the reflected light off a piece of foam-board. Here, the length of the foam-board is important just as the length of the box would be: it should be long enough to cast its reflection on the entire height of the bottle or the desired height wanted. The further the foam-board is placed from the bottle, the longer the foam-board has to be.
I wanted the light to be thin. The flaps (barn doors) permit me to adjust the thickness.
When illuminating the foam-boards, make sure light doesn't spill on the outside face of the flaps.