I was tickled to find that among the many sites featuring how to make a
spectrometer, was one that permits uploading a spectrum captured by a
digital camera as a jpg which will depict or return a spectrogram or a
comparison spectrogram. I see that a 1000 lpm diffraction grating
(replica) is now an economical article of commerce.
This seems to imply that a few minutes of handiwork can provide
spectrograms with 1 or 2 Angstrom resolving capability in the visual
spectrum.