Posted by Alan Uomoto on June 17, 1999 at 15:02:27:
the main things being to avoid the 5577 night sky line (not a problem for [HST]) and make the Balmer jump a filter boundary. Including the z band near 1 micron is also important since that's where most of the new discoveries will be. In all, this made sense from the standpoint of finding faint galaxies to target for redshifts but it turns out that for most stars there's a good UBVRI transformation so the usefulness of the system ought to be comparable to other wide filter sets. The simplest and most important reason for using SDSS filters is that there will soon be more stars photometered in that system than all others combined. An arrogant but practical truth. A few years from now (WFC3 launch time?) much of the sky to 23rd magnitude will have photometry in this system and most people will be able to query a database for their favorite "bright" objects and do the usual broad band photometry things. You want to avoid the wrath of WFC3 users who will think (and say) "What were you thinking when you didn't install SDSS filters?"