My viewfinder went dark on me while taking pictures last night. The camera still takes pictures fine, but I can not see anything in the viewfinder. I see an 1842 on the screen when I first turn on the camera. Did a setting get changed when I swapped out the battery?

That may be because (in case you had not noticed) it is dark at night. As you have given us no information regarding the equipment you are using, we cannot be more specific.

Have you tried pressing the display button ? It should switch from LCD to viewfinder.

Think that you might have accidentally pressed the DISP or DISPLAY button on the back of your camera. This manually turns the LCD display on and off to save batteries. You would then use the optical viewfinder in its place. To turn the screen back on, just press the DISP button one more time.

Do you mean the viewfinder or the lcd-screen?
The Nikon D80 does not have a 'live-view' mode to watch the picture you're about to take on the LCD-screen. It's a semi-professional camera not to be used like a standard 'point-and-shoot' digital camera.
If it is the viewfinder that's out of focus, try adjusting the dial to the right of the viewfinder. It might also be that your internal mirror doesn't get powered (in this case you're unable to see the focus areas). In the last case you will have to get the camera serviced by Nikon.

Sounds like you accidentally pressed the DISP (Display) button on the back of your camera. This manually turns the screen on and off in picture taking mode to save battery power. You could then use the optical viewfinder in its place. To turn it back on, just the DISP button one more time.

I have had "dark pictures" from each of my Nikon DSLR (D70, D80, D200, D300) cameras usually when taking pictures from a tripod and/or the self timer. Situations where you take your eye away from the viewfinder which allows stray light to enter thru the viewfinder and throw the auto exposure way off. Not sure if this is what is happening to you.

no there isn,t.but these cameras do not have enough flash to take great pictures at night,for one you cant be to far away,two you have to have a subject in range of the flash,other wise all you get is darkness.but at the most 10ft is the farthest you can go and still get a great shot at dark.also use auto mode when taking pictures,because it adjusts to light-dark etc.i know this because i have the same camera and its awesome,plus im a photo technician and ran a photo lab for 3years selling digital cameras. good luck,hope i helped

It sounds to me that you are using an incompatible lens or a broken one. Does this happen with the lens that came with the camera?

That would explain the darkness if the lens is stopped down. It would seem the aperture control is faulty on the camera body. Normally, the aperture remains open until you take the picture. It is only closed down while the shutter is open.

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