Zeiss lens for Yashica AF

It must have something to do with the "Super" labeling on the barrel. :)

A few forum posts elsewhere do seem to confirm your suspicion that it's made by Sigma, and I think it makes perfect sense why they'd make it in Yashica AF, since they already had the experience and tooling to make it a no-brainer choice as another mount for an AF lens made in the 90's.

There's a particularly long thread on photo.net that pretty much cements them as the likely maker, and one posting noted a marking on the barrel, as "LENS IN JAPAN UNDER LICENSE FROM VEB CARL ZIESS JENA", and there's also a Sigma branded version with enough visual cues to call it a twin. It bears an "APO" marking, suggesting there's some 'special sauce' in the optics too.

One individual post by 'rob_h|3' gives specifics on what mounts these were available for, if anyone would prefer to jump into the meat of the topic, and immediately before that post, he shows the brochure pages where presumably the details came from.

Something slightly related pops to mind while on the subject... the Yashica C/Y to AF adapter does a really good job of adapting the manual Zeiss and Yashica lenses to the AF bodies, so there's an alternative path to using other 3rd party prime or zoom lenses, although strictly speaking, they aren't exactly a normal 3rd party supplier in this case.

It probably wouldn't be the first time that someone may have been a contract supplier under 3 brands, and produced essentially the same lens for every one of them. Three bites at the apple, may not leave much more than the core. [TM, by me, if anybody's gonna quote that! :)]

If the CSJ doesn't have any APO marks, does that mean it has no special glass elements inside, or just no marking to announce it/them?

just tested Zeiss Sonnar 200/3.5 with the AF adapter but on 230 AF. remember there is lightloss.  in shadow or nonlit area with less contrast AF nonworking. EOS worked. maybe on 300 AF it will work better. instruction is telling which lenses are adviced to adapt. up to f 2.8 135/2.8 is largest adviced with AF-adapter. i think 1 1/2 stops losing.

Hi.  They certainly did make a few in addition to some primes, such as the lovely 24mm Super-Wide MkII and 400mm f5.6 in both APO and non-APO versions. 

And of course, with your Yashica AF cameras, the Sigma 400mm f5.6 AF is a fine performer too.

So called Carl Zeiss Jena Zoom lenses from the 80's have been usually made by Sigma.