While a booster on the shuttle had a bit more than twice the thrust of the shuttles engines at take-off, I'd venture a guess that it produced on the order of a thousand time more visible light. In fact, this may be an example of both the brightest and dimmest large rocket engine exhausts for heavy, sea-level launch.
Are there any tables, or approximate data for the relative visible-light brightness of major rocket engines? I'm not looking for IR or UV or anything of particular military or defense interest, just the ordinary commercial and civilian rockets that people can watch launch.
What originally got me thinking about this is that this question was marked as a duplicate of this question within 2 hours, apparently with the idea that any old rocket launch can be seen for about the same distance, perhaps about 100 km away.
I was originally wondering if there is really a "standard rocket brightness" or if some rockets used today are still far brighter or dimmer than others, but as @RussellBorogove points out in comments a large number of launches include solid fuel boosters which tend to be very bright.
So I'd like to ask this question about brightness on the basis of individual propellant combinations, not total launch brightness.
My guess is that for a large engine at sea level, the brightnesses rank like this:
SRB > RP-1/LOX > UDMH/N2O4 > LCH4/LOX > LH2/LOX
Am I wrong?
below: Space Shuttle Discovery from here. Scroll aaaaaaaall the way own to get a better estimate of the total brightness. Note that the hydrogen/oxygen flames are so dim that you can still see right through the flames.