At last I got some raw test files including LCCs for tech ultrawides for a Hasselblad back using the KAF-51000 CCD sensor (50.3 megapixel 47x39mm). It exists in the CFV-50 (recently discontinued) and the current H5D-50, and the older H4D-50 and H3DII-50, plus all the various multishot versions, H5D-200MS most recent.
This sensor has 6 um pixels just as the Dalsa sensors used in most current Leaf and Phase One backs, but has a few important differences. 1) it lacks microlenses, 2) it has much stronger shielding between adjacent pixels, 3) there is no tiling.
Looking at results from SK28 (the most extreme tech wide angle lens ever designed in terms of angular response) shifted all the way to the 90mm image circle edge I was really surprised with the result. There are none of the issues the Dalsa sensor is plagued with. Crosstalk is minimal (not visible), there is no tiling no matter how you pull the contrast, no microlens ripple (of course), color cast is there of course but certainly managable. As the sensor shields its pixels instead of crosstalking there's quite much pixel vignetting though, 2 2/3 stops at the 90mm edge (about 1 stop with the crosstalkin' Dalsa), so in tough light conditions with shadowy parts at the edge you may want to bracket.
I think this is pretty revolutionary results. Why? While backs with this sensor has existed since 2008, I had no idea until now that the Hasselblad 50s worked so well with tech wides, while the ubiquitous 6um Dalsa is plagued with issues and I've seen Capture One bending backwards to fixup microlens ripple, residual tiling (and indeed bent myself backwards to fix this in the LCC algorithm in Lumariver HDR I develop) and not always succeeding 100%, and certainly leaving crosstalk desaturation behind and sometimes even demosaicing failure. Resulting in people giving up the traditional designs and going for the more expensive retrofocus Rodenstocks.
Certainly many are happy with that, and the more complex Rodenstocks wides are indeed sharper when peeping, but among us that are still on legacy backs and happens to like symmetrical distortion free designs (both for how they render the image and the lower weight and price) this opens up an opportunity. As an alterantive to the "Phase One and only upgrade path" one can get one of the 50 megapixel Hasselblads, get some more resolution and perhaps more importantly buy a number of more years of time hoping for new sensor technology to arrive that better support tech cams (like a larger CMOS with wide angular response).
This is not only about the SK28 and SK35, although it's more evident on those. Also the 43XL, 47XL and 60XL through their super-large image circles push the Dalsa sensors into trouble space if you're the type that shift large amounts. With the Kodak 50 megapixel - no issues.
I find it surprising that Hasselblad marketing has not pushed this advantage more. Oh well, not too surprised, it's quite obvious that they're clueless when it comes to tech cams. But it's a bit sad that they have missed this opportunity to seriously compete with Phase One in the tech cam sector. I am myself a highly technical user (as I also write imaging software) so the fact that I have missed this performance advantage should surely mean that many/most others in the tech cam community have too.
In the future I hope more people will be aware of this option though when thinking about upgrading your legacy 22/33/39 megapixel back.