Nikon D50 Photos fade to black?

I have a Nikon D50 and in every photo it fades to black at the bottom. What is causing this and how do I fix it?

P.S. This happens for all of my 3 lenses so it is probably the body.

Get the mirror action checked out. It sounds
Like it is not in sync with the shutter.

In any event, you need a professional repair, so get it checked out.

I'm betting it's the mirror, though.

One example with full exif would have eliminated all guesswork and would have allowed a diagnosis.

I'm betting on the shutter which means it's an economic writeoff. Time to find a refurbished D90 I'd say