For artwork photography, I want to have the painting "perfectly" parallel to my camera sensor, in order to improve sharpness and reduce the amount of post-processing in my workflow.
Are there dedicated tools available to achieve this ?
The camera grid is usually too large to get precise results, and I gave a try to the mirror technique (you put a mirror in at the center of the artwork, if you see your lense in it from the viewfinder or screen then you got the right alignment), but it is a pain to set up and I found the results as imprecise.
I was suggested a tilt-shift lense but I feel the issue of relying on my eyes within the viewfinder will be the same.
Spirit levels may help but couldn't fix the horizontal angle between the two vertical planes.
I was thinking about a 4 points laser rangefinder to be mounted on the camera, does something like that exist ?
Note that I can usually move the artwork (placing it flat on the floor might work for small pieces, but not for larger ones, though).