At the moment, I'm using Impossible film in Spectra format. So far, I'm not getting the good results I got earlier with Impossible 600 or SX-70.
What I'm getting is high contrast with blown highlights and no shadow detail. I'm using a Polaroid Image 1200 camera and, as long as I hold the release down, the film won't eject. This technique lets me get to a place where I can eject the film and immediately keep it in the dark for an hour. At least that's one good thing.
EDIT: After thinking about it, the high contrast, blown highlights, and lack of shadow detail are likely due to my 2-year old refrigerated first-generation Impossible film. Actually, it has a sort of "Three Kings" Ektachrome appearance at times, so it's starting to appeal to me a bit as more artistic than literal.
One discovery I made from these results is that instead of the usual dial that moved a progressively lighter or darker translucent wedge over the photocell (allowing for fine exposure control), the Spectra has a switch that allows for just -2/3, 0, +2/3 compensation. That's it. There is no other granularity. This is explicitly stated in the service manual. Oddly, the service manual touts this as an improvement (well, yeah, it's just a circuit rather than mechanical parts, but bad for the customer).
To me, the Spectra is several steps in the wrong direction compared to earlier Polaroids. Odd that they actually fetch more money.
My other Spectra complaint here:
(there was a url link here which no longer exists)