Time to replace your mirror. It is highly likely it got damaged after slapping into the EF-S extension every time the shutter was pressed.
er...in case you don't understand..... Mirror does NOT slap into the rear of the lens.
If it does, there is no pictures captured on the CMOS.
Anyway, it's just to see what's the quality of the image like outside of the 1.6X crop factor within the full frame. Perhaps a newspaper test will be better to gauge the image quality.
Cheers,