28mm Tang Special

Welcome to the forum thierry ... I'll make some assumptions about your lens without seeing pictures, but one thing I can tell you without hesitation is that there are no Yashica branded lenses with "Tang Special' markings on them. Any lens that has that label may have been marketed under a 'Tang' or 'Tang Special' brand and has a C/Y or M42 mount, but it was not made by, or re/branded for, Yashica.

Of the lens photos I've seen after doing a brief Google image search for "Tang Special" 28mm lenses, most of the visual results show the same basic lens configured in one of several popular bayonet mounts, and doing a text search on DuckDuckGo for "Tang Special" lenses will show several Ebay listings for one of these same lenses in C/Y mount. I can't say with any degree of confidence who the 3rd Party manufacturer was, but there are a few clues to suggest some possibilities, so assuming that your lens matches those same photos...

1. The grip on the barrel isn't a seperate piece of rubber, but is milled into the metal barrel and has a tiny chromed bevel at the outer edge.
2. The screws used to assemble the lens are tapped into the barrel in conspicuous spots - like the milled grip area - and aren't hidden. Plus, the construction method itself is more external than internal, which suggests it's made with major cost savings in mind.
3. The serial number ends with the capital letter 'E', and begins with "No.", with no space between it and the following numbers.
4. The majority of the lettering on the barrel is italicized, uses predominantly green markings in addition to white, and has a unique stylized typeface, especial in the 'fat' and rather pronounced number shapes.

The milled grip suggests that it might be made by Mitake (or even Makina Optical), and matches several I have, or have seen, that have been branded and sold as Lenzar, Spiratone, KMart's 'Focal' brand, Albinar (i.e., as "Best Products", w/ "Albinar Special" markings) and others. Two milled grip types I have that also have the 'externally' tapped screws in them, are the Lenzar MC 135mm f/1.8, and a Focal MC 200mm f/3.3.

Others on the forum here may have other possibilities on the maker, but in my experience each maker has a pattern of manufacturing, where they will always reuse the basic techniques and machining tools across any lenses they may rebrand for others to sell, and matching them up can usually get you close to the actual manufacturer. That goes all the way to the specific color schemes and even the specific hues of paint colors. These makers can have a massive amount of money tied up in their machining tools, and end up buying paint in a truck load of 55 gallon drums.

I freely admit to complete lack of awareness of 'Tang Special' lenses; had it not been for Thierry's posting I would have continued in blissful ignorance.

But it has led me to eBay item number:125953985554 in which you can see one of them; a 28mm f2.8 lens in C/Y mount, being sold with a Yashica lens case.  I can't find any reviews of Tang Special wide-angle lenses, so image quality remains a mystery.  It looks very like an old Raynox w/a that I have tucked away somewhere..