Looking that the Rebel XT pictures, I've noticed that blue on black now seems in fashion for DSLRs, and tangentially it reminded me of the colour scheme for a Carl Zeiss Jena lens I have in KA mount. A 24mm/f2.8 which isn't really the best performer (not really sharp till f5.6, and lots of vignetting).
What is the history of these lenses? Are they rebadged? Rather plasticky, and the focusing is a little rough but I'm rather fond of it.
They were made by Sigma. They had an agreement with the East German Carl Zeiss in the eighties, and made some lenses for them, 3 or 4 zooms and the 24 mm. you mention.
Sigma and MInolta also made some zoom lenses for Leitz, in the R (SLR) mount, sold under the Leica name, with Leica prices.
Carlos