"And how does the webcam version do its image?" Here is link on how to make a 2D image with specroheliograph and a webcam. Look under spectroheliographyhttp://www.astrosurf.com/thizy/lhires3/index-en.html
All you do is make a movie the spectral line of interest as the Sun drifts across the entrance slit of the spectroheliograph. From each frame of the movie, the image of line is cut out and stack next to each other. The narrower the slice, the narrower the bandwidth of the image. One can get down to 0.2A without much trouble.

- Dave