Image Circle Size for 55/1.4 APO-Distagon and 135mm f/2 APO-Sonnar
A lens projects an image circle, the size of which is its “coverage” or the size format it “covers”. Quality doesn’t necessarily stay high to the edge of the image circle, but as shown with the Touit designs, it can extend well beyond the stated format size (see 12mm coverage and 32mm coverage and 50mm coverage and more 12mm coverage).
It turns out that the Otus 55/1.4 APO-Distagon and 135mm f/2 APO-Sonnar both have quite large image circles.
The extreme corner of a 36 X 24mm frame is 21.3mm; these graphs show vignetting out to the 27.5mm corners of a medium format 44 X 33mm sensor (Pentax 645Z).