Dark spots on images

Sounds like dead pixells to me.
Replace the screen if it is worth it.

If these spots are in different places on each picture, then they are actually reflections of dust particles in the air from the flash being so close to the lens. If they are in the same place on each picture, then they are indeed water spots on the lens.

To autofocus the sensor needs a fair amount of contrast (light and dark eges) to operate. If you're trying to take a photo in a dim room of a dark colored subject for instance the focus won't lock and the camera won't take the picture. Try switching your lens to manual focus and shoot that way.

This is a digital camcorder, and not a digital camera (Hitachi DZ-HV 575E).
Although it can take still pictures, its primary focus is on taking video.
Most camcorders today do not include a built-in high-intensity light. If you need to take video in dark conditions, then you'll need to buy a separate light source designed for video production.
That same light source should work for your still images as well.

There is a spec of dirt that made it inside the camera and has landed itself on your image sensor.

If you take a picture and the image has a spot on it, it could be the screen. If you transfer it to your computer and the spot is in the same spot, its something on the image sensor. You would have to send it out for cleaning, and a new camera would be cheaper.

If your lens is clean.

The dark spots maybe your image pickup sensor going out. Try going into the menu to tools select pixel mapping see if that helps it will look at all your pixels and determine if they are bad & try to compensate.

Hope it helps. Good Luck! please let me Know if this works or if you need more help.

I have a little dark spot that i noticed it today too on my canon SD870IS i hope somebody can tell us what's the problem

check the shutters, it prob not opened all the way

learning to use light metering correctly can have its challenge.
the manual will guide you on how to set up to read light from the subject. spot metering a dark area will cause general overexposure, or a washed out look. spot metering a bright area will cause a dark image. if you are on spot meter and shoot two people standing together against a bright lit background, your meter will see between them if they are centered, and read all that bright background, setting the camera to a less sensitive combination of aperture / shutter speed, resulting in a dark image. use field averaging meter setting and be sure you are metering the subject and not the background. try shooting a wall that is fairly clear of other colors and uniform it light hitting it, you should have a correctly exposed image. since it works in other modes (at least 1, anyway) then it is unlikely you have an exposure compensation issue. that is the only other non defect issue that would cause your problem.
once you confirm that you have these settings correct and still get a dark image, its time to have it serviced.
good luck
mark

The two pictures were shot at dramatically different exposures - the "dark" one at 1/1600 shutter speed, f7.3, the "light" one at 1/320 shutter speed, f4.0. This accounts for the great difference, as the exposure conditions for the "light" one allowed much more light into the image during the exposure period. You didn't tell the whole story of how you set this up, I think you were shooting in a "spot" metering mode, where the particular exposure conditions the camera uses would vary considerably whether you were aiming at a dark area (making the picture light) or a light area (making the picture dark). I would make two recommendations: Switch your metering mode to "center weighted" (the mode labeled "[(•)]"), and also change your ISO setting to AUTO, as there would be no reason for shooting these photos at ISO 200 that I can think of.