The 80mm XL lists an image circle of 212 mm at f22, and a max rise of 34mm portrait. I am trying to test this on my Ebony 45SU, which has a max rise of 70mm. I set the camera at max rise and film in portrait orientation to map out the vignetting and to see how much difference various size filters make. Much to my surprise, at max rise I do not see a well defined vignetting line, just a gradual fade over the top couple of centimeters. With step up rings and filters (72, 77, 82) I see a sharp line from about 3 to 2 centimeters from the top edge of the film. This is still better than the stated image circle. What is going on with this lens? Is the stated image circle really conservative, or is there image degradation toward the edges I am not seeing since I am shooting a blue sky? Someone should stick one of these on an 8x10 and see what the full image circle really is.:-)
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