Adquo; tonning of your negs might be an outcome of old/used-up fixer. I've seen that.
Hyakjae; how you can see rodinal is something of a cult object among photographers. Rodinal is cheap and effective and simple to use. I would suggest, that you start with normal development first and establish you own time for lower dilutions like 1/25 before you move to high dilutions and long times. There is no point in too long times, the emulsion will be swollen too much and this isn't a good thing at all. If you have your time for 1/25 go to 1/100 and develop for 4x the time. After that there will be very little action as rodinal will be almost gone. Much longer time will not help with underexposed film. "Stand development" stands for a lack of agitation during development. Usually a bad thing, but in case of rodinal there is some magic. (Hence the "cult" thing.) Anyway Agfa suggest at least 10ml of concentrate per full (36) roll of film in the solution for proper development. Now word of caution. If you have a bottle of original rodinal it is few years old and that's fine. It will be fine for the next 50 years as long as is unopened. Once you let the air in it will oxidize . At slower rate then anything else, but neverless. If you slow with using it up, and with rodinal usually is the case, the concentrate will loose the strength. Your ratio of concentration and time will become invalid, negs will look like underexposed. Happend to me. Since then I distribute whole bottle at once in 5ml portions using medical vacutainers and use a syringe to remove the air.
Good luck to you.
