I conducted careful tests on my Omega 10x10 Chromega F lamphouse to determine light fall off and discovered three phenomena: a) The difference in light fall off between the upper right hand corner of the print and the lower left corner is 1 full f/stop (0.3 density units) at all magnifications (1X, 2X, 3X, 4x). The upper right hand cornet exhibits almost no light fall off (as compared to the center) whereas the lower left hand corner exhibits the worst fall off. b) At magnification = 1X, where there should be no fall off, the difference between the upper right hand corner and the lower left hand corner is 0.3 density units = 1 full f/stop. c) There is a "white" line right down the middle of the print. I am positive that the enlarger is aligned (lamphouse, lens, baseboard) as I spent the better part of a day aligning these three surfaces using a high-accuracy machine level. I cleaned the two glasses in the negative carrier and the enlarging lens has no scratches. My guess is that the lack of uniformity is coming from the lamphouse itself. I know that the Omega F lamphouse is not famous for its unifotrmity buy 1 full f/stop is a bit much, IMO. What can I do to improve the situation?