Lighting is definitely half the battle, which is why a histogram function would be very useful.
Back in the days of 16mm film, there were some remarkably good results to be had if you had the right combination of film stock, lens and lighting.
Top end C-mount lenses are hard to come by now and as has been said, if we're going to use what are essentially CCTV lenses wide open with not enough light, the results are not going to be great.
The #1 priority should be to get more light so at least you can stop down whatever lens you have.
If you have some SLR lenses then buy an adapter and try them, but they will also inevitably give you soft results if you don't have enough light to get them into the sweet zone.
There is quite a lot you can do to the video once you have it in an editor. Even basic editing software has color correction functionality these days.
Here'a a comparison of some original Chronos footage at 800x480 (top) which has then been color corrected and sharpened in Edius:
https://youtu.be/trwI64UiwgsThere could also be more quality to be gained by playing around with the re-encoding and interpolation methods when converting the native resolution Chronos files to whatever final resolution you want to play it at.