When Pentax released its 24-70mm f/2.8 lens back in 2016, people quickly realized that it was little more than a rehoused Tamron lens without the VC feature. More recently, Pentax has announced that it's developing a new FA* 85mm f/1.4. Although there are certain physical similarities to a Sigma lens, I doubt that it's the same lens.
At this stage, it's difficult to make any definitive conclusions about what this latest lens from Pentax is or isn't. Most of the specifications have not yet been released. We don't currently know how many optical elements and groups will be contained in this newly announced lens.
Having said that, Pentax has released enough information for us to have some warranted suspicions. First of all, just look at the lens. I mean, putting it side by side with the Sigma, as I have done in the lead image of this article, you can see some very significant similarities. The bulbous top section of the lens with a slimmer lower section looks very similar to the Sigma 85mm f/1.4 Art lens, but with a different housing. The comment sections for several sites are discussing this very point too.
If, however, you go to the Ricoh website, you'll see that they have released some of the major specifications for this upcoming lens. Aside from the physical similarities, which are striking, the paper specs don't fit the theory. Although the minimum focusing distance and the minimum aperture are the same as the Sigma, the remaining specifications are not. The Pentax lens, for example, contains three low dispersion elements, whereas the Sigma only contains two. In my view, this alone makes the Pentax a different lens from the Sigma. Other differences include the filter thread size and the physical dimensions of the lens too.
If this newly announced lens from Ricoh is in fact a rehoused Sigma lens, I don't think that's a bad thing by any means. First of all, the Sigma 85mm is one of the best on the market. In my experience, it produces brilliant results. Wide open, this lens is able to capture lots of detail, and it's one of the sharpest on the market right now. If Ricoh has rehoused this for their K-mount, maybe that's not a bad thing.
The Pentax 24-70mm is lighter than the Tamron lens, and even the physical dimensions are different too. Ricoh obviously made some changes to their version, and in my view, improved it. I think a mid-range zoom lens doesn't require stabilization, especially considering the fact that the K1 Mark II already contains IBIS. Therefore, having a lighter full-frame zoom lens is essentially more useful.
If Ricoh has rehoused the Sigma, my guess is that they've probably improved on this already incredible lens. Based on that, I don't think anyone is going to be overly disappointed if that is the case. Taking a look at the filter threads on both lenses, the Pentax lens tapers on the top, and maybe that slight change allowed the smaller size. That in itself is a very useful change, because filters above 82mm are harder to find and more expensive.
Of course, as of right now, this is merely speculation in the comments sections, and although at first glance, it appears that Ricoh has rehoused the Sigma, I'm not convinced that is the case. I think that this is more than likely an original lens from Ricoh, which Pentax shooters should be very happy about.