This is not the legendary Pentacon 135mm f2.8 which someone call “monster of bokeh” because of its 15-blade diaphragm. The Pentacon 135mm is made by Meyer in former GDR (East Germnay) but the lens in the photo above is made in Korea probably by Korean optic giant Samyang. Not much information about this lens can be found on the Internet. Based on what I know, VEB Pentacon did outsource their lenses to out of Europe manufacturers like Sigma, Cosina and Samyang but they should all be B bayonet mount lenses, not M42 like the one in the photo.
After some lengthy digging, I finally found some information on this particular lens. According to what I have read, this lens is a M42 mount Korean copy of the GDR made B-mount Prakticar 135mm f2.8 which itself is a re-mounted version of the Pentacon 135mm (made by Meyer, 5 elements-4 groups Orestor formula) with 6 instead 15 diaphragm blades.
Well, that’s probably enough for the origin of this lens, how about some sample photos? Both were shot with Fujifilm XTRA400 color negative.
About this Praktica 135mm f2.8…
This 135mm lens came with the Praktica MTL5 I bought and so far I would carry this compact fast telephoto with me whenever I am shooting my MTL5. Optically, it is pretty sharp and focus is also very smooth. However, I might just have high expectation on prime lenses regardless about optical design and manufacturer, I would just say this lens is good for its price but it is just not exceptional.