I tried a little experiment today. This was inspired by Daves (dmeckert), who used a beauty dish with a grid and a "shower cap" (under the grid) both on the beauty dish at the same time. I wanted to see the difference with different modifiers.
Slightly, :OT:, I know. I'd put this in the lighting thread, but since Daves shots here inspired it, I thought I'd put it here.
Here's the setup. The small statue is 9.5 inches tall, exactly 3 feet from the background and 16 inches from the beauty dish. The beauty dish is a Mola "Demi" 22". I shot with my D3s (tripod mounted) and the 24-70/2.8. All shots were at 70mm, ISO 200, 1/125, and f8.0; WB set for Flash. The strobe is an Elinchrome Ranger RX, set at it's lowest power. Light was metered, using a Sekonic L-358, with the reading taken right between the two faces. All of these are straight out of the camera, except for resizing for web viewing.
I did not feather the dish, but kept it centered on the statue. BTW, 16" was as close as I could get to the subject without the dish getting in the way. Relative to the subject size, 16" is a long way, so the resulting light is fairly hard.
To my eyes, the differences are subtle. I think they're most noticeable in the shadow to the left of the statue. Also, the last shot (with the grid and the shower cap), looks to me to be about a stop underexposed relative to the other shots, but I think it may actually be the most accurately exposed.
I'd like to try this again with a human model. I think the light-to-subject distance here might make the differences harder to detect.
I'd appreciate anyone else's take. Thanks.
Set up:
Last shot - Beauty dish with grid and shower cap under the grid: