Now how close can you get? A couple decades ago when I used film, I did a super closeup shot of a CRT screen and got down to just 6 "pixels" filling the frame. The setup was a Nikon FE2, extension bellows, 62mm reversing ring, and a 20mm f/2.8 mount in reverse with the rear element just about touching the glass of the screen. Even with so much of a light source, it was so extended that it stlll required a 25 (or so) second exposure. Some day when I get a slide scanner I can show these old photos.