DIY Laser levelling using webcam and laser level

[devmonkey]

It could be aliasing from reflections on the lens holder thread, I got much better results with the sensor mounted with nothing close to it in the near field. See picture below, that window started off as a 6mm round hole, it caused aliasing hence I opened it up so no reflected laser light could hit the sensor.

I don't know much about dslrs but maybe it could have lens distortion correction built in which would be warping the image non-linearly across the sensor. Have you got a cheap web cam to try with? It is also unlikely that sensor pcb is hard fixed to the body, the ones i've take apart are usually on soft mounts that let the board move around to absorb shocks.