I have a Canon XTi. On every photo I take I have a thick diagonal black line appear on the photograph. See an example picture:
My next discovery came when I selected Sensor Cleaning: Manual
in the camera options which makes the mirror move up and out of the way of the sensor. I then took a picture looking at the sensor. There is a thick plastic thing in the way of the sensor. Here is a picture:
Does anyone know what this plastic thing in front of the sensor is? It is still attached to the camera so I cannot pull it out.