I have a 5D Mk III and just noticed today that all my photos from the weekend had a significant portion of the bottom right hand side black. see attached example.
I salvaged shots with cropping.
I then looked into it a bit and it seems to occur with any lens (definitely occurred with the 100-400 and the 100mm macro).
Then i went through a series of images and was surprised to see it steadily progress over time!
Never really noticed the very slight problem initially but it is now quite significant.
I guess I'm going to have to have the camera serviced (i have had it a few years now).
But any idea what is causing it? Its not lens hood petals (i use circular hood) its not flashes, it cant be the curtain timing as this would be horizontal at bottom.
Its got me stumped...especially the progressive worsening.
Any ideas as to cause/ remedy?