What do you think of this adapter?
 

In this case, what's happening is the diffusing screen doesn't diffuse nearly enough, leaving most of the aerial image in and resulting in an overall sharp, bright, grain-free and minimally-vignetted image. Which is fantastic, except this nullifies the use of the adapter. On the shot of the water with sunlight reflecting off it, the specular highlights should "sparkle" in the background, whereas when out of focus on this particular adapter they are simply being blurred. This is what I like to refer to as "greasy" bokeh. I'm guessing this is an SLR focusing screen of some sort? In either case it would be better to layer two on top of each other or find a screen that diffuses more.

If the out of focus effect is what you desire than take no heed of my comments. Also, better out of focus qualities may be achievable by closing down the SLR lens' iris.

I practically agree with you. I wouldn't use this screen for "bokeh" at all. Light loss is incredible. Maybe 1 stop?, no grain(vibrating) and no vignetting. Cool thing is I can change the screens in a flash. It's actually Polycarbonate screen. Light Shaping Diffuser. The other one I use is better bokeh, decent light loss and still no grain, and the screen comes from a cell phone so it's free if you find a broken one nobody uses anymore. It's free of smudges, but might get some dust on there, really easy to spary off with air in a can.

I'll try and see if the two are better than the one for "bokeh".

The comments got me very curious to see this footage but I've been trying to download it for ages and it keeps saying "Sorry, there are currently no free download slots available on this server"

Any chance you might post it else where? I'm really curious.

http://www.filefactory.com/file/7b26c2/

Up now, might not be in a few days.