Different Flash Diffuser tests for Low Key lighting

I was quite disappointed that I couldn't achieve proper low key lighting with my current setup so I did this little test to figure out how each diffuser is affecting the light quality.

I use all the diffuser I have. omnibounce , inflatable softbox ( about 8" x 6") and lumiquest bouncer.
I also shoot with manual mode without adjusting the aperture to see the light loss from different diffusing method. As usual, I had no choice but to use myself as a guinea pig.
They are all shot inside my room so there's constraints about the camera:flash:subject ratio to control the light diffusing into the back wall. I put myself as far as I can from the wall to minimize the light falling into the background and put the flash as close as I can to me too.

All photos are shot with EOS 30D, Sigma 18-50mm f2.8 EX DC lens at f3.5, 1/180s ISO 200 , focal length 46mm.
Camera is 3' away from subject. White wall behind me 2.5' away. 430ex flash on 1/64 power beside me right 1.3' away.
pardon the focusing.. cos i m too lazy to use remote.

first, unprocessed version .. you can see the light loss from different diffuser by looking at the brightness.

now the lightroom processed version to compensate the exposure / levels..


In my opinion , the inflatable softbox is most useful as it has minimal light loss, less stray light casting on the wall and the soft quality of light on the subject.

Lumiquest bouncer + white trash bag give me the best soft box effect at the cost of light loss.

I think getting a silver umbrella and swivel is the ultimate solution for controlling that kinda lighting.

Anyway.. after that test.. I wanna go try getting the shallow depth of field and low key lighting using strobes .. So I made this self portrait.. Its really hard getting the focus on my eye and the right framing. Not the best composition but this is what I can get.

430ex on my right 1.5' away with inflatable softbox + a layer of white tshirt to even lower the output. flash at 1/64 power triggered with ST-E2.
50mm , f1.4 , 1/80s ISO 100.

cheers..