This is my third prinitng session and I tried printing a 6x7 negative this evening working with the exposure, contast filter etc. On all of the prints one side is slightly out of focus while the other side is sharp. I noticed this in all of the other printing sessions. as well. I thought it was something wrong with the camera but the negative are sharp throughout the whole negative when viewed on the light table with a loupe. A light bulb came on and I wondered if it could be the tilt of the lens plate? If the lens is not parallel with the plane of the paper could that cause this? if not what else might it be?