If you are working on the same roll of film and you have a contact sheet for reference, once you have printed one image , you should be able to make an educated guess on the next images contrast and density by just looking at the differences on the contact sheet.
Usually, and in your sample contact case the contrast filter should be the same and you just need to change your timer setting. I always start with a 10 - 15 second exposure, this way you can start mentally storing density changes based on the 10 seconds in % . After time you will be saying to yourself.. Damm that image (on the contact sheet) looks 20% darker than the one I just printed , and you will immediately set your timer 20% less on you next test and without changing contrast you should be very close.
Also by looking at your contact sheet you will be able to judge areas that need dodging and burning, remember that once enlarged the effect will be a little bit more pronounced than the contact shows.
Originally Posted by tkamiya