Mirroring image is small with HDMI over Sony tv
I have an early Apple tv model MC572LL/A and when I show a film over mirring from the iPad pro it is only about half the size of the screen but it shows full size through Apple tv from the iMac also when watching a film it stops over the Apple tv but still runs on the iPad pro. Any ideas also does anyone think will it show full screen if I purchase the latest Apple tv?
Ta.
iPad Pro, iOS 12