Well, i did a bit of traveling here recently, and i didnt want to drag along my entire setup..light stands, umbrellas, softbox and so on. So i took a gamble and purchased a Gary Fong diffuser, basically the lightsphere. I researched a couple of others, but this one seems to be a bit more portable, and cost effective. I will post some pics and its settings so you can have a general idea how it works and "how i took it"
this first shot was taken indoors with really low light, 0.7EV ISO100 1/50sec 65mm f3.2 spot metering. I angled the lightsphere above my lens and came out with decent soft results.
next image i took, it was damn near dark outside, so i decided to angle the lightsphere at 45 degrees coupled to my SB910 set at 0.7EV Center Weighted metering, f2.8, 1/50sec 45mm
Did the same deal with this image..again, it wasnt even close to being sunny outside, as it was dark and gloomy, same settings as above minus it being 35mm
I took all of these photos in worst case scenario type of situations. At first, i was a bit hesitant on using something that looked like a giant piece of tupperwear ontop of my 600 dollar speedlight..but it works none the less.
I have tried the lightsphere mounted to my SB700..which produced slightly different photos. It does seem to stop down your speedlight a bit, which is why i found myself shooting at 0.7EV, however, it produce decent results. this is a great alternative when you are on the go and need to produce some decent shots.
Now i have read some reviews in regards to this diffuser, most were against this particular diffuser considering it stops down your flash by a full stop...however, as i mentioned above, it still produced a decent shot considering. Do i think something like this can replace an umbrella? no..of course not, however as i already stated, you dont always have the option to drag along your entire setup. Also i tried other shots using the stock SB910 diffuser..which ended up producing a lot of flash flare and didnt spread the lighting as much...but it also didnt bring my flash down a entire stop.
I also found it to be mounted to my SB910 VERY securly..i could literally hold my entire setup by the lightsphere with confidence. I did not purchase the collapsible version, but the one that comes with the rubber band and velcro strap..not as portable, but definitely more secured.
if anybody is looking for a decent portable diffuser, this is a good one for the money (30 bucks). JMHO>
on a side note, i saw some knock offs at amazon for like 19 bucks shipped. I read reviews of their rubber odor, but i couldnt imagine it not being able to produce decent results as well.