I tried this with little success. The c-mount is such a cropped sensor that even with the EOS lens adapter you only get the middle of the shot... also I haven't found a good solution for focus and f-stop that is buried inside the EOS pin protocol. I'm sure it's solvable but haven't found it yet.
The big problem is unless you use fisheye lenses like 6 or 11mm full frame (35mm equivalent), the full frame equivalent focal length you get with the HQ camera sensor is practically in the exotic telephoto range, it's a crop factor of like 5.2x.
It's nice for things like astronomy (your nice 200mm f/2.8 is now 1000mm+) or bird/nature watching, but it's highly impractical for anything but specialist portraiture or walk around use.
Most of the c mount lenses available are pretty poor, and getting focus right with anything not way stopped down (especially without a large display) can be super tricky.
I also use Spark, I love everything except their "Compose a new email" button. To me personally it is a bit hidden. But as I mostly respond to mails, it's not that big of a problem to me.
Btw tags never worked for me anyway, but Spark has cool functions regarding bringing the really important (personal) mails to your attention. Also, their function not to jump to the next mail when you finish reading one is brilliant. I hate accidentally opening a mail I don't intend to read at the moment and then having to mark it as unread.
