In almost all forums , I read that the Industar 61 LD 50mm lens has more contrast and is sharper than the Jupiter 8 50mm lens. I recently bought a very nice 1957 Jupiter 8 lens from RetroPhotoHouse , polished aluminium with external knurled focusing knob.Focusing and apertue operation as smooth as silk . At the same time I bought a new/old stock Industar 61 LD (1990) from another Ebay seller.Lens is just as smooth and in great condition.These were to use on my 1957 Zorki4 when it arrives from Oleg at OKVintageCamera.As Oleg says "Any soviet camera or lens ó small lottery. As other soviet production they may have unstable quality. You may get excellent thing or absolutely unusable item. So, if you have a good Jupiter lens ó you win that lottery. For any LTM camera I can recommend Industar-61 lens. Itís a cheap, but may get nice picture (if you win the lottery!)" As the Zorki hasnt arrived yet I did some very controlled testing with both lens on my 36mp Sony A7r and the results were surprising.The Jupiter 8 was not only sharper but had better contrast than the Industar 61 LD.Perhaps its like Oleg said - I won the lottery with the J8 but losy it with the Industar 61 LD.For around 25euro is it worth trying again with the Industar with another lottery ? Appreciate any thoughts.