Ray - , Dec 18, 2010; 03:02 a.m.
Do you have aperture preview button? If so keep pressing it and look at front of the camera - is the aperture blades closing all the way down?
Look in front of the camera to see the blades ....
If you don't have it.... do a long exposure like 5 seconds in manual with lowest f number ... if the lens is closing all the way down .... there is your issue.
I had that on my new D70.
Keep pressing it, it might be random. Like if you have a 2.8 lens, set at 2.8 and it should be all open. 2.8 should not close all the way down .. like f/16. If you do you get black *seriously underexposed* pix.