When I attempt to enlarge a 4x5 negative full frame to 8x10 paper, I get one corner (only) vignetted. This is my first attempt with a 4x5 negative enlargement since I just got my lens! I am using a 45MXT enlarger with a 135mm Componon. After removing the carrier, the enlarger is adjusted so that the light circle is at its widest. The upper adjustment on the enlarger (sorry, don't know the real name) is at the lowest position. I have experimented with the adjustment up and down. It is kind of hard to tell, but it does seem like that the edge of the light circle is protruded upon by the edge of the projected image, thus causing the vignetting... (In case it matters, I am not having this problem with my other lens (105mm and 6x7 negatives)) I know I can crop out the vignette, but what is the right way to fix or investigate this? Thanks in advance. Steve.