Yes i am talking about the marks, but thought the marks on the senor is black and not purple? but the marks are not always in the same place.DJL329 said:If you are referring to the dark blotches, such as the ones about an inch above the person's left eye in the photo, then you may have debris trapped behind the shutter. If so, try performing a manual cleaning using a bulb-type air blower, like this one:
See page 299 in the 5D Mark III manual on how to start a Manual Sensor Cleaning. It locks up the mirror and opens the shutter, so you can use the blower. You can download the manual here:
You may need to hold the camera so that the lens opening is facing down (e.g. above your head, so you can see what you're doing), so that any debris falls out.
Here's a simple how-to video: