"solved" Spots on image NOT DUST OR OIL!

Can you visually inspect the sensor using a magnifying glass?

Oil left on glass can cause coating damage, and can etch the glass.

Fungus can grow on glass, and emit acid, which etches the coating and the glass.

As it is more visible when closed down, the spots should be on the surface as you look at it.

This is purely a guess, but the "sensor" you're cleaning is actually a sandwich of filters, with the actual sensor located behind them. Perhaps moisture got inside the filter stack, possibly after using the camera in very wet/humid conditions, or maybe after bringing it in from extreme cold into warm temperatures? If so, it can be repaired, but it's going to cost you to have a pro do it.

As I look at it I'm more and more convinced that this is what it might be. It's the same pattern I see in storm windows made up of layers of glass, where moisture somehow got inside the stack and will reappear in humid conditions, but otherwise exhibits only the faintest of spots where the moisture was but evaporated.

Originally Posted by Englischdude

assuming that this is correct, I must add that the Cluster of spots is only at the centre of the Image. moisture would come in from the edges correct so would such dots not start at the edges of the image?

That's why I'm drawing the parallel to a window pane - while moisture is obviously drawn in from the edges it seems to collect in the center where there may me the most room to expand due to resistance/pressure being lowest in the center of the sheet than at the edges. In other words, if you take two flat pieces of anything and press them together at the edges, the center point would be where forces keeping them together would be weakest.

Again, just a theory based on what I'm seeing with no real world experience seeing it in a camera. Take it to a shop and have them take a hard look at it.