In article <4fmts4$150i@saba.info.ucla.edu>, dinh@I_should_put_my_domain_in_etc_NNTP_INEWS_DOMAIN says...

>I can't figure out why my N90 is always 2 stops underexposed in Apature
>mode. Before heading to a Nikon dealer, can some knowledgeable person
>please tell me how to fix this problem.

Have you checked to see if any exposure compensation has been set?
(I assume that you have set the correct ASA on the camera....;-)
Hope This Helps