To my surprise, Stoffen actually makes a diffusion dome for the tiny unit. I can't imagine how this would contribute to improved light quality, but obviously somebody did.
I bought it for two reasons: I was curious to see how it would perform with my Nikon D40, and being the ultimate Nikon Fan Man, I thought it was cute. Count on it, I'll buy something that I want, and will spend a lifetime justifying the purchase.
Ken Rockwell puts great stock in the unit, firmly believing that it's the only on-camera flash a photographer really needs. I would agree with him, if my needs coincided with his, which they don't. After all, he probably created the "Cute Photos Of My Kids" genre of blog photography. And while the photos are technically fine, they're just not to my tastes.
Normally, I would use the SB-400 only as a fill light for my Tokina 10-17mm fisheye. In this sample made on an overcast Halloween celebration, the fill just barely provides enough light for a decent catchlight, which is about all I wanted or needed. This shot, taken in 2008, was probably the last time I actually used the lens.
I noticed the placement of the Exposure Compensation Dial (see down arrow, above), is conveniently placed for manipulation by my right thumb. I didn't give much thought to its usefulness because I seldom make adjustments in either of the two automated exposure modes (aperture and shutter). When used in Aperture Priority, rotating the dial can increase or decrease the exposure by lengthening or reducing the exposure time, respectively. (I have no idea how the camera would respond the the Program or Fully Auto exposure modes, as I never use them). However, when the camera is in the Manual Mode, the shutter and aperture are set by the user and not the camera. Rotating the Exposure Compensation Dial will have no effect on the exposure duration or aperture size. Unless...
There's A SB-400 In My Hotshoe! That's right! I can use the dial to adjust the output of a shoe-mounted SB-400. I suspect this is the only speedlight that can be so adjusted because exposure compensation in the iTTL Nikon Speedlight is controlled with the + and - control buttons at the 3:00 and 9:00 positions of the Multi Selector. The SB-400 has no Multi Selector, but this might actually work.
I tried it out on a Nikon D70 and it appears to also work. It did NOT work on a D600. But the SB-400 could be the ideal pairing for the P7700, since the flash exposure compensation would be right under my thumb, providing I remember to shoot in the Manual Mode, and confine myself to using the flash as a fill light.
When I have a chance, I'll try it out on something real.
More to follow...