I nearly always rate T-Max 100 at 50 and at 25 if needed. Just be careful not to over develop and blow out the high lights. Use a low contrast developer to supress the density in the highlights. My negs look beautiful when handled this way and are easy to print. T-Max 100 has so little grain that I can barely see it to focus when making a 16x20 print. Never under ANY circumstances under expose TMX or TMY for that matter.