Defects between the layers of glass covering the sensor of a Canon EOS Rebel T6s/760D. Photo by Lensrentals.com, 2015

LensRentals received its first Canon EOS Rebel T6s/760D and T6i/750D units and has identified a sensor problem with a number of those cameras. Out of about 20 total units (around 10 of each model), 4 T6s and 2 T6i units contained sensors with noticeable defects in their sensor stacks. These layers of glass on top of the sensor contain a pattern of dust-like spots or particles that are visible when studied under angled (rather than direct) light. 

What looked at first like a pattern of dust on top of the sensor revealed itself to be defects within the layers of glass that are layered right on top of the chip. LensRentals' Roger Cicala reports that the effects of the problem can be seen from about f/11 to f/16, and will appear against a white background or clear sky. However, images taken at wider apertures didn't display the issue. 

Cicala reports that Canon is aggressively looking into the issue and that it's being taken seriously by the manufacturer.