Thank you both for your replies. The viewfinder is ok when the menu button is pressed. It also works ok with all the other photographic modes eg aperture priority etc. If the sensor was dirty I would presume the viewfinder and screen would remain blank for all the modes. The manual mode settings...
This problem is evident right from the time the camera is switched on and before any photos have been taken. In other words I can't see thru the viewfinder or see anything in the monitor. Currently I have to compose and set my focus in Aperture mode and then switch to Manual mode to be able to...