[Wavytone]

Hi Alex, I've tried this before with both large artwork and engineering drawings. FWIW I used to have an A3 Microtek scanner years ago, but eventually sold it when I no longer needed it.

For a modest outlay a large flatbed scanner is the way to go because ultimately the number of pixels it can produce will vastly exceed the pixels available from single frame of a camera sensor and the resolution available from camera lenses - even the best ones. Sure you could make a mosaic of several images stitched, but a flatbed can do that too.

For a small volume of scans there are also bureaus that can scan anything up to 56" wide as a continuous sheet for a modest cost. This I suggest will be far the best option rather than buying a large scanner. You may have to stay and be there to get it right, but once you know the settings its straightforward.

The camera idea has a whole host of issues starting with uneven lighting. It's hard enough using a camera to copy A4 - I've used my Panasonic GX85 and GX series lenses with fair results - but far from perfect and nowhere near as good as a flatbed can do.