Here is the result. It is a no-shopped straight-out-of-camera JPEG.
The backdrop is a 70x140cm softbox with one of my trusted Metz 40MZ flashes, radio triggered by Hähnel Combi TF in it. I had to clip a sheet of half WD in front of it to eliminate the visible wrinkles in the front diffusor (tracing paper will do, too). The key light for the pumpkins is another 40MZ, bare bulb from the right and just a bit higher than the subject.
Of course, you can go the traditional way and light a white sheet of paper with two angled softboxes. But the way of using the ´box itself as backdrop saves you space and work. Of course, you can fire any light through two or three sheets of tracing paper, even your desktop lamp will do. But you will have to raise ISO then, since you don´t want the motion of the color to blur. Strobes simply have more power than anything you can muster in your household.
I chose a power setting (which I don´t remember) for that strobe and adjusted exposure taking test shots and watching my Canon 40D´s overexposure warning in the instant playback. Close the aperture step by step, until you have a white background that does not overexpose in every area. This is how you do it best, because you avoid the flash that looks directly in your lens to cause purplish blooming around the subject, softening the whole scene and screwing up contrast. If you want to work the traditional way (or shoot film), you can also meter the light. You´d need 2 stops more on the background than you get from the key light (i.e. the light that actually lights the subject). The best way would be spot metering with a gray card in place of the subject and using a meter that has an engraved zone scale. Put the background "white" to zone IX, the subject light to zone V and go. Shooting slide film, play safe and bracket downward.
With speedlights in a softbox, there is always some hotspotting. Speedlights direct their light to the front. Every speedlight does that. Studio strobes don´t. They have true bare bulbs that really behave like a lightbulb in your regular lamp at home and emit light without directing it. A speedlight will always create a hotspot in any diffusor, because it is designed to emit light forward, not backward or to the sides.
I placed the hotspot in my setup in the middle just above the pumpkins. In fact, you can see some falloff to the lower corners of the backdrop which does not really matter in the final shot or print and can be shopped out easily. But I´m pretty much of a slide film shooter (work-cleanly-and-leave-tings-as-they-are) so I like it and leave it like that.
The pumpkins are resting on a sheet of white acrylic glass which creates the beautiful reflections without any Photoshopping. This means that you can get only as many shots as you have corners, sides and numbers of identical acrylic glass sheets. You just won´t be able to clean up the color mess good enough to not piss you off for the next try. There will be residue. Just buy two more, so you can keep going for a while before it´s time for a coffee and cleaning break for the whole team.
Oh yes, talking about team! You need someone to pour the color. Or you build some remote-controlled mechanism that can be adjusted to pour the right amount in exactly the right place that you can control with some sort of foot pedal and... oh well, just get someone to do it. It´ll save nerves.
We employed a freezer bag from which we cut off a corner. Filled with paint, it´ll give a nice stream that can be controlled by your helper. Don´t cut off too much and test the stream before screwing your most beautiful pumpkin and the damn expensive acrylic glass sheet! Also, cover everything with garbage bags and newspaper. Cover more than you think might be right. Play safe. Hand your helper some rubber gloves.
It is important to try out the frame rate that you can shoot with the flash power you have chosen. Nothing worse than shooting some cool frames of pouring paint and then finding out that on the best shot one of your flashes didn´t fire. Try and find a rhythm that allows your strobes to recycle. Here are the shots before and after the winning shot:
|Paint flowing behind stipe and a little too less paint.|
|Too much paint already - game over for pumpkin and acrylic glass.|
Always shoot at the fastest sync speed possible and keep your working lights down. It keeps the room light from effectively illuminating the scene. Although it´s not really "freezing motion" to shoot slow flowing paint, you don´t want any ghost images here but a clean, crisp shot. Use a tripod and arrest everything safely. Compose your shot thoroughly. Clean your acrylic sheet with glass cleaner and a lint-free cloth beforehand. Play safe and don´t screw up your carpet. Remember, these are all unedited JPEGs from my camera and I think that they look pretty decent. That is due to good preparation.