I am form Russia and I use very good Tasma Type-17 film (it is Russian film for aerophoto shooting). The main issue of this film is high contrast, but it has very good grain and tonality. By experience I found the best developer for the film - POTA (phenidone - 1,5 g, sulfite - 30g). But I would like to try sharpness variant of this developer, if it possible. Could you be so kind to say what could I try to add to developer? I would try to add potassium carbonate, but I am afraid for contrast elevation. Thank you.