@cpixip Thanks for taking the time.
The “not looking wrong” part, to me, is the difficulty to introduce sharpness without introducing digital artifacts (or sharpen the noise too much). De-noising as a first step does make sense, but DaVinci’s noise reduction has been kind of disappointing in that regard. As soon as I manage to make a frame look “nice”, during playback, there’s always one area that has become wobbly or has other kinds of artifacts in it.
In the video you’ve posted over here, for example: Super-8 enhancement, progress report - #35 by cpixip there is some funky movement in the mountains at around 0:50. I’ve found it near impossible to avoid things like these happening unless I turn down noise reduction so much it’s barely visible anymore. (NeatVideo seems to do better in that regard, but I’m currently too stingy to buy the Pro version).
That’s why I’ve mainly focused on slight sharpening. But as @Utrecht and @cpixip say: each clip is different and typically not of the same quality (focus, grain, lighting etc.), so you really have to adjust whatever filter on a clip-by-clip basis, if you want to do it right. So much work!
The Texture Pop filter seems to do a good job separating areas of the frame. I’ve found it possible to sort of “exclude” the grain from the areas I want sharpened. But I’m fairly sure I’m not ready to do this for each clip separately. Just leaving it here as another tool that hasn’t been mentioned yet. 