Run the internal exposure test at 3600 dpi increments of 5. Before running the test set an exposure that is about 100 less than you have for 2400, this will be a good place to start. Using a densitometer, measure the Black square for 4.00 plus and then the 50% square looking for 50%. Don't get caught up in a specific density other that over 4.00. This is a good solid black and after that all you need be concerned with are the dots. The AV25 is a very linear device provided the optics are clean and with a 50% dot on the exposure you will be +/- 1% up and down.
As for where to put the exposure number that you select, that depends on the RIP you are using. Harlequin - Page Setup; Agfa - On the AV25 Control Panel.
