35mm lenses which are very sharp over the frame fully open are rare, and expensive.
Very good reputation you will find with Zeiss (East Germany, Flektogon, and West-Germany, Distagon). The Distagon you may sometimes also find named differently from Voigtländer and Rollei (identical optics, probably except the coatings). The ECB Fujinon-W mentioned by
dcshooter plays in the same league. I also often heard praising of an Olympus Zuiko. All these lenses were available in M42, the Distagon also with PK (so I think).
But back to your problem with the Takumar:
Some time ago, another PF member opened a thread to ask which Pentax lenses are sharp without degradion when used fully open.
I remember
stevebrod named the Takumar 3.5/35mm!
So either
- stevebrod was wrong
- you got a lemon
- there is something you are doing wrong
What can be done wrong with a 35mm lens?
- If you shoot fully open for reasons other than wanting small DOF, it may be because you need the amount of light. In this case, your exposure time may also tend to be longer than wanted - can cause slightly unsharp results on pixel level..
- There was never a problem to manual focus with analog cameras - but they had big bright viewfinders and split screens. With APS-C and smaller, darker viewfinders suddenly even some experienced photographers found it difficult to manually nail focus precisely. This seems to be a problem mainly with lenses in the range between 30-35mm. I guess the reason is that longer lenses support nailng focus better because of the narrower DOF, and with even shorter lenses accurate focussing is not so important anyway. But this effect is not the same with all lenses, it obviously depends on how a lens is rendering slightly out of focus areas. Specially the Zeiss lenses are famous for their "3D" effect, which also makes manual focussing a lot easier. Automatic LV focussing is effected the same way, as contrast measuring will be easier and more precise with "3D"-effect lenses.