Having shortly returned from a trip to The Lakes, I find that the majority of my images have a slope on them. It's very obvious where images include lakes or tarns, one side of the water is noticeably higher on the image than the other. I was aware of an issue whilst taking shots and on occasions did tilt the camera so that the image appeared level through the viewfinder. However, at the time I assumed that the issue would likely only be present through the viewfinder and not on the captured image. I was using two Canon 350D bodies with different lenses. In both setups, the slope is present. The only things I can think of that were common to both are that prior to the trip, I had the sensors cleaned on both and I adjusted the dioptric setting on each camera. If one of the lenses could in anyway have caused the issue, they were swapped a few times between the camera bodies before the trip. Appreciate any suggestions.