I have used Tetenal ultrafine for 100 and 25 that worked fine for me, it should work for 400 as well. its a very finegrained film with nice tones I would like a little more contrast. but the detailes in shadow and light areas are so fine, that I put up with it. With ultrafine, you can not push nor pull. Try it. The times recomended is all right.(posted 9866 days ago)