>>4290225There's 2 i know of that Ive done. You need to preflash the film and push it heavily, this can be done by double exposure, with a tissue folded over in front of the lens so you get an even exposure across the frame as your first exposure then your normal exposure.
The only issue is that you need to calibrate the exposure level specifically for the film, as I did it across varying exposure levels, nothing happened until the preflash hit a certain level and then all of the exposure jumped up and looked like it gained about 2 stops. You also don't want to the preflash exposed too high as it'll just give you fogged images. Did it on superia 800 Xtra a long time ago and pushed it hard in c41, but it'll work across any film in theory.
I had some other developer recipe for CMS20 that greatly improved the usable speed and DR. Someone posted about it along time ago if you can Google it. It's mostly a phenidone recipe with stand dev taking it to iso100. Keep in mind that recipe is far too weak for foma etc as fine grain films like cms20 develop very fast and take very little developer activity to develop.
You could probably take a normal recipe and tweak it though, like a phenidone:hydroquinone recipe and alter the P:HQ ratio, more phenidone less hydroquinone will give lower contrast ratios which you can use to counter pushing heavily, though just a normal dev will work very well with preflash
