If you do a lot of scanning, it's worth getting one of these from Vlad (a great guy and you can support Ukraine at the same time, if the spirit moves):
For film camera users: Hi-Res Test Targets on 35 mm, type 120 and 4x5" film, USAF 1951 Charts for film scanning with DSLR or mirrorless camera
film4ever-digital.blogspot.com
I've shot with two macros, testing all apertures from f/4 to f/16. One is sharpest at f/5.6, the other at f/11. Neither at the proverbial f/8. Go figure.
I don't worry too much about light balance (though I do have a very good light source). After scanning, it goes through a "developer" (Neg Master or Neg Lab Pro) and then Photoshop anyway. Sharpness for me is everything.