After a number of successful years with the x t20 I notice big dark spot on images. Inspected lens and sensor for what the cause is. It is a large visible spot on the sensor. It looks as if it could to hardened oil but not sure. I have ordered a cleaning kit but a few weeks away.
What is the likely source of this stuff? It is not dust so I am assuming oil. I have not changed lenses outside my office, but I recently purchased several used fuji lenses. I tried them all in my office and took each one out and tried it outside. Everything went well until today. I noticed the dark spot on the images. I did not need to stop down to see the dark spot on the images. The spot on the sensor is quite large and easy to see and when viewed with a loop the spot appears translucent on the perimeter and nearly opaque nearer the center. It looks dry or baked on.
Anyone have an ideas what I'm dealing with. (This will be my first attempt at sensor cleaning, no good local repair shops-this is boonies.)