Make sure you don't have live view on.

Live view is a camera mode where you are able to view the camera's current POV much like the eyepiece, except that you are able to simulate your exposure settings / software optical filters (such as sepia and contrast/white balance enhancement) on screen (assuming your camera has a screen).

If live view is on, you will not able to see through your eyepiece when taking a photo and every time you take a photo, the shutter has to:

• pop out of live-sensor mode, into the eyepiece to start from scratch

• take the photo (pop back to the CMOS sensor for your exposure time).

• quit sensor exposure by popping back to the eyepiece

• snap back to live mode after a couple seconds (this would be the noise you speak of, kind of like opening to an infinite exposure)

Live view itself is partly a limiting feature of the camera when it is on in that, you will not be able to take another photo until it "snaps back to live mode". This process takes a few seconds because the camera is still storing to memory the first photo you took, and won't start live mode again until this has completed.

If you are knowingly using live view but still want to take multiple photos quickly, you may be able to use your camera's burst mode.