Carson Wright

I know it's a bit out of your budget, but I love my Sekonic L-858D. Having the spot and incident meter in one device is incredibly convenient. In 2 years of use I've never had any problems with it at all.

It's not that higher stops always equals a sharper image, it's that lenses have a "sweet spot" of optimal sharpness and diffraction that's usually somewhere in the middle of the aperture range. It's always a good idea to do some camera tests and find out all the unique properties of the particular combination of filters, lenses, and stock you're using.

Some of the softness could also just be poor lens performance. You might have shot at, say, f2.8 whereas your lenses perform best in terms of sharpness, aberration, distortion, etc. at f5.6 or higher. The only way to really find these kinds of things out is with camera/lens tests.

Here's an example of a Bolex H16 being mounted on a Movi M5: A similar set-up could probably work with a K3, but it certainly doesn't look easy or cheap.

Looks cool, reminds me a bit of Giuseppe Andrews' work.

I use the Angelbird Ursa Mini match pack shooting BRaw on the UMP G1 and have never had any issues: https://www.angelbird.com/prod/match-pack-for-ursa-mini-1834/