Tamron Japan has posted an intriguing teaser image on its Instagram account, just in time for an announcement at either WPPI or CP+ (probably the latter). The backlit image is all we have to go off of, but naturally, speculation is running rampant online.

Canon Rumors thinks this might be a 100mm f/2 VC or a 135mm f/2 VC, while Sony Alpha Rumors received an anonymous (and therefore still highly unreliable) tip that it is in fact a "28-75mm F/2.8 Di III RXD" for Sony FE mount. Based on the design alone, we're leaning towards calling this a zoom lens—notice the two rubber rings and the gap between the top ring and the top of the lens.

As user Sharlin points out in the CR forums, the design is very similar to the Tamron 18-200mm F3.5-6.3 Di III VC.

Of course, all of this is errant speculation until Tamron decides to officially announce whatever its teasing. But if you have any educated guesses about what the lens might be, drop them in the comments along with your reasoning.